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Hindawi Publishing CorporationDataset Papers in PhysicsVolume 2013 Article ID 926470 5 pageshttpdxdoiorg1011552013926470
Dataset PaperOptical Constants of 120572- and 120573-Zinc(II)-Phthalocyanine Films
Michael Kozlik Soumlren Paulke Marco Gruenewald Roman Forker and Torsten Fritz
Institute of Solid State Physics Friedrich Schiller University Jena Helmholtzweg 5 07743 Jena Germany
Correspondence should be addressed to Torsten Fritz torstenfritzuni-jenade
Received 16 November 2012 Accepted 17 December 2012
Academic Editors T-H Fang S Kiravittaya S K Kulshreshtha and H-P Wagner
Copyright copy 2013 Michael Kozlik et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
We present a dataset of the optical constants of 120572- and 120573-zinc(II)-phthalocyanine (ZnPc) They were determined accurately fromtransmission and differential reflectance spectra with the surface roughness taken into account For this purpose thin films wereprepared on quartz glass substrates via physical vapor deposition and characterized by ultraviolet-visible (UV-Vis) spectroscopybefore as well as after a well-defined annealing process Kramers-Kronig consistency of the optical constants obtained was checkedby means of a numerical algorithm
1 Introduction
Zinc(II)-phthalocyanine (ZnPc) is a promising material fororganic electronics especially photovoltaic devices It hasalready been applied in prototypes of solar cells [1ndash4] Fur-thermore it is already known that phthalocyanines (includ-ing ZnPc) can exist in multiple types of crystalline phases[5] in particular the metastable 120572-ZnPc (higher electricalconductivity) and the stable120573-ZnPc (lower electrical conduc-tivity) [6] need to be distinguished Structural analysis of bothphases and detailed information about the phase transitionas shown in [7] are needed to set suitable constraints for anumerical model to determine the optical constants of 120572-and 120573-ZnPc Once the optical constants are known theycan be used for modeling layer systems or even photovoltaicdevices or vice versa for a nondestructive optical analysis ofthe crystallinity of ZnPc layers Here we present a reliablemethod for the determination of optical constants of organicthin films where the surface roughness is taken into accountFinally we present a detailed dataset of optical constants forpolycrystalline 120572- and 120573-ZnPc covering an energy intervalfrom 12 eV to 50 eV
2 Methodology
Thin films of ZnPc were prepared via physical vapor deposi-tion on quartz glass Quartz glass was used as substrate dueto the low absorbance in a broad spectral range (119896 lt 10minus7
between 300 nm and 850 nm) After thorough in situdegassing the ZnPc powder obtained from Sigma-Aldrichwith 97 chemical purity was thermally evaporated from aceramic crucible in a tungsten boat and deposited at a rateof 06 As under high vacuum conditions (pressure 119901 sim10minus5mbar) To realize the growth of the 120572 phase ZnPc was
deposited on substrates kept at room temperature [8] Aphase transition from 120572-ZnPc to 120573-ZnPc upon annealinghas been demonstrated in the literature [7 9 10] Here thestable 120573-ZnPc phase was obtained from the metastable 120572-ZnPc samples via annealing under ambient conditions for3 h at 240∘C and above Films of both phases with differentthicknesses from 30 nm up to 150 nm were examined bymeans of a Varian Cary 5000 UV-Vis spectrophotometerThetransmission measurements were done using a light beamperpendicular to the sample surface while the angle of inci-dence is 12∘ in reflection geometry In both cases unpolarizedlight was used The spectrophotometer was operated in adual-channel mode which enhances the long-term (severalhours) stability significantly The scanning velocity was setto 300 nmmin (averaging time 02 s) in the NIR region and120 nmmin (averaging time 05 s) in the UV-Vis region witha fixed spectral bandwidth of 5 nm and 4 nm respectivelyThe resulting resolution is by far sufficient for the typicallinewidths of organic thin films at room temperature Themeasured optical spectra were analyzed by a numericalalgorithm implemented in Wolfram Mathematica 8 in orderto extract the complex refractive index (119864) = 119899(119864) minus 119894119896(119864)
2 Dataset Papers in Physics
0
02
04
06
08
1
15 2 25 3 35 4 45 5
Exp Fit
Tran
smitt
ance
900 600 300
Wavelength (nm)Re
sidua
ls
Energy (eV)
001
minus001
150 nm120 nm90 nm60 nm30 nm
(a)
900 600 300
Wavelength (nm)
0
02
04
06
08
1
Tran
smitt
ance
Resid
uals
002minus002
15 2 25 3 35 4 45 5
Exp Fit
Energy (eV)
150 nm120 nm90 nm60 nm30 nm
(b)
Figure 1 Experimental dataset (open symbols) consisting of (a) 5 samples of 120572-ZnPc and (b) 5 samples of 120573-ZnPc with various nominalthicknesses characterized by one transmittance curve each and the curves which were fitted with a single set of optical constants used forall layer thicknesses (solid line) In the lower part the residuals 119879th minus 119879exp of the fitting process are shown For the sake of clarity subsequentresidual spectra are displayed with a vertical offset The insets show the respective scale bars for the residuals The nominal film thicknessesare given
of the thin film where 119899(119864) and 119896(119864) denote the photon-energy-dependent refractive index and extinction coefficientrespectively
The determination of the optical constants is possible bymeans of a simultaneous analysis of transmission (T) andreflectance (R) spectra However here the reflectance datawere replaced by differential reflectance spectra (DRS) [11ndash13] Thereby the need for a calibrated mirror can be avoidedIn the following the basic ideas of the numerical algorithmwill be explained In order to interpret the measured opticalspectra of ZnPc thin films the numerical treatment is basedon a layer model consisting of the substrate and the organicthin film as well We used the generalized matrix formalismbased on the Fresnel formulas for mixed coherent and inco-herent layers as outlined in [14] In order to improve our layermodel we analyzed the interfaces by non-contact atomicforcemicroscopy (nc-AFM) [7] Accordingly the root-mean-square (rms) roughness (sometimes also denoted by thesymbol 119877
119902
) of as-deposited as well as annealed films of ZnPcwas found to be small but not insignificant with respect to thefilm thickness 119889 (rms119889 lt 20 for 120572-ZnPc and rms119889 lt 5for 120573-ZnPc) Hence for an accurate determination of the
optical constants the values obtained for the surface rough-ness at the air-to-ZnPc interface have to be taken intoaccount This was done by modified Fresnel coefficientsconsidering only partial coherence due to phase differences ofthe transmitted and reflected beams by Gaussian-distributedirregularities as outlined in [15] Because of the azimuthalorientation of the grains the in-plane component of theoptical anisotropy can be neglectedThe substrate was treatedas incoherent due to its rather large thickness (063mm) withrespect to the coherence length of the light This means thatwe indeed account for multiple reflections at both substrateinterfaces but internal interference effects do not contributeto the signal An optical characterization of the quartz glasssubstrate used was done by transmission measurements inthe UV visual and near-infrared spectral region in order toextract the refractive index individually assuming negligibleabsorption (119896 = 0)
As a matter of fact no dispersion model for ZnPc isrequired in the calculation Accordingly the algorithm startswith a set of optical constants that is the refractive index119899(1198641
119864119894
119864119873
) and the extinction coefficient 119896(1198641
119864119894
119864119873
) each consisting of 119873 points to be fitted to
Dataset Papers in Physics 3
900 600 300
Wavelength (nm)
15 2 25 3 35 4 45 5Energy (eV)
DRS
0
0
0
0
0
Resid
uals
1
minus1
01minus01
Exp Fit
150 nm120 nm90 nm60 nm30 nm
(a)
900 600 300
Wavelength (nm)
15 2 25 3 35 4 45 5Energy (eV)
DRS
0
0
0
0
0
0
Resid
uals
02
minus02
1
minus1
Exp Fit
150 nm120 nm90 nm60 nm30 nm
(b)
Figure 2 DRS signal (open symbols) of (a) 120572-ZnPc and (b) 120573-ZnPc and the fitted curves (solid lines) In the lower part the residuals of thefitting process are shown For the sake of clarity the spectra are displayed with a vertical offset The insets show the respective scale bars
the experimental data In this work the energy interval from12 eV to 50 eVwith a step size of 001 eV results in an119873of 381If only one pair of transmission and differential reflectancespectra is used for the extraction of the optical constants 119899and 119896 then the film thickness needs to be specified preciselyto prevent the algorithm to produce large errors in the opticalconstants or even to get stuck in a nonphysical solutionSeveral optical spectra which are not necessarily of the sameoptical quantity analyzed in parallel using the same values forthe refractive index 119899(119864) and the extinction coefficient 119896(119864) ofthe thin film for all spectra were used to overcome this issueas suggested in [16] Consequently five samples with nominalthicknesses of 30 nm 60 nm 90 nm 120 nm and 150 nmrespectively were measured (nominal thicknesses beingdetermined with a quartz crystal microbalance) The objec-tive function to be minimized is
120575 = sum
119895
119873
sum
119894=1
119860(119895)
(119864119894
)
times 119883(119895)
th (119899 (119864119894) 119896 (119864119894)) minus 119883(119895)
exp (119864119894)2
119899 119896 variation997888997888997888997888997888997888997888997888997888997888rarr min
(1)
where119883(119895)th denotes any calculated quantity (eg transmissionor DRS) to be fitted to the respective experimental data119883(119895)exp
The index 119895 is used to distinguish between the differentsamples with different thicknesses Each signal of T and DRSwas weighted by a factor 119860(119895)(119864) as described in [17] in orderto equalize the information 119883(119895)(119864) from all spectra havingoriginally differentmagnitudes119860(119895)(119864) is calculated from theminimal (119899 = 1 119896 = 0) and maximal (119899 = 3 119896 = 1) valuesof the refractive index and extinction coefficient expected forphthalocyanine thin films [16] The advantage of this proce-dure is that the layer thickness can be optimized as well usingthe nominal thicknesses as starting values By doing so it isimportant to cover an appropriate thickness range of layersfitted simultaneously as only thickness-dependent internalinterference effects contribute significant new information tothe fitting procedure Moreover it was found that the fit isthen rather robust against different starting values for thefilm thickness even if they are far from real The rms valueswere treated as fitting parameters likewise except the firstrms value which belongs to the 30 nm ZnPc film where nosignificant gradient in the objective function was found Thefit itself was carried out by means of a Levenberg-Marquardtalgorithm
Figures 1 and 2 show the fitted spectra for both phases ofZnPc as well as the corresponding residuals of the fit for thetransmittance and the DRS signals respectively In Figure 3
4 Dataset Papers in Physics
Table 1 Nominal and optimized values of film thickness and rms values of the samples used for the determination of optical constants Theerrors given are statistical errors from the fitting procedure
Nominal thickness (nm) 120572-ZnPc 120573-ZnPcOptimized thickness (nm) rms (nm) Optimized thickness (nm) rms (nm)
30 3695 plusmn 003 11 plusmn 03 3615 plusmn 005 mdash60 6530 plusmn 004 31 plusmn 02 6190 plusmn 007 54 plusmn 02
90 9663 plusmn 004 77 plusmn 01 9465 plusmn 008 45 plusmn 01
120 13215 plusmn 005 106 plusmn 01 12909 plusmn 007 59 plusmn 01
150 16890 plusmn 007 132 plusmn 01 16788 plusmn 007 56 plusmn 01
the resulting spectra of the optical constants for 120572-ZnPcand 120573-ZnPc are shown Furthermore the optimized filmthicknesses and respective rms values including the standarddeviations of the fit are shown in Table 1
The optical constants for 120572-ZnPc and 120573-ZnPc thin filmsobtained reproduce the spectral measurements very nicelyAs one can see the residuals are very small compared to thetransmission data The edge at 350 nm (354 eV) is caused bythe internal light source changeover of the spectrophotome-ter used but is smaller than the mean residuals and thereforehas no significant influence
The results were checked afterwards for Kramers-Kronigconsistency As described by Nitsche et al [17] the integralcan be split into an additive offset which is energy indepen-dent and an integral the over important region (12 eV to26 eV energetically lowest optical absorption band) whichshows the spectral characteristics to be analyzed In thisregion model-free Kramers-Kronig consistency was con-firmedThe numerically obtained rms values are in very goodagreement with those from our own nc-AFM images [7]and those presented in [18] Without considering the surfaceroughness the fit is less suitable which results in slightly dif-ferent optical constants especially in the ultraviolet spectralregion Our data of 120572-ZnPc compare favorably with thoseof the almost identical molecule copper(II)-phthalocyanine(CuPc 120572-phase) from [16 19]
3 Dataset Description
The dataset associated with this Dataset Paper consists of 5items which are described as follows
Dataset Item 1 (Spectra) Spectra of 5 samples of 120572-ZnPcwith various nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves whichwere fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sake ofclarity subsequent residual spectra are displayed with a ver-tical offset
Dataset Item 2 (Spectra) Spectra of 5 samples of120573-ZnPcwithvarious nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves which
9001200 600 300
Wavelength (nm)
03
252
151
05
0
252
151
05
119899119896
119899119896
151 2 25 3 35 4 45 5Energy (eV)
Std dev (times5)
Figure 3 Spectra of refractive index 119899 and extinction coefficient 119896 of120572- (top) and 120573- (bottom) ZnPc respectively The standard deviation(statistical errors from the fitting procedure enlarged 5 times) isindicated by the reddish error margin
were fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sakeof clarity subsequent residual spectra are displayed with avertical offset
Dataset Item 3 (Spectra) DRS signal (open symbols) of 120572-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 4 (Spectra) DRS signal (open symbols) of 120573-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 5 (Spectra) Spectra of refractive index 119899 andextinction coefficient 119896 of 120572- (top) and 120573- (bottom) ZnPcrespectively The standard deviation (statistical errors fromthe fitting procedure enlarged 5 times) is indicated by thereddish error margin
Dataset Papers in Physics 5
4 Concluding Remarks
Different crystalline phases of ZnPc namely 120572-ZnPc and120573-ZnPc have been characterized optically via UV-Vis spec-troscopy Reliable data for the optical constants of bothzinc(II)-phthalocyanine phases could be determined whenthe surface roughness was taken into account Kramers-Kronig consistency was confirmed numerically afterwards
Dataset Availability
The dataset associated with this Dataset Paper is dedicated tothe public domain using the CC0 waiver and is available athttpdxdoiorg1011552013926470dataset
Disclosure
The authors do not have a direct financial relation with thecommercial identitiesmentioned in the paper thatmight leadto conflict of interests for any of the authors
Acknowledgments
The financial support by the Thuringer Ministerium furBildung Wissenschaft und Kultur Grant no B515-10030and by the Deutsche Forschungsgemeinschaft (DFG) Grantnos FR8759 and FR87511 is gratefully acknowledged Theauthors thank Prof Dr Carsten Ronning for making hisequipment for optical spectroscopy available to them
References
[1] I Kim H M Haverinen Z Wang et al ldquoEfficient organicsolar cells based on planar metallophthalocyaninesrdquo Chemistryof Materials vol 21 pp 4256ndash4260 2009
[2] C Florica I Arghir and L Ion ldquoProduction and characteriza-tion of CdTe wire arrays for hybrid inorganicorganic photo-voltaic cellsrdquoDigest Journal of Nanomaterials and Biostructuresvol 6 no 1 pp 21ndash27 2011
[3] L-C Chen and B-H Liu ldquoPorous silicon layer patterned fromanodic aluminum oxide and application in ZnPc hybrid solarcellrdquo Electrochemical and Solid-State Letters vol 13 no 4 ppH108ndashH111 2010
[4] S Bereznev R Koeppe I Konovalov et al ldquoHybrid solar cellsbased onCuInS
2
and organic buffer-sensitizer layersrdquoThin SolidFilms vol 515 no 15 pp 5759ndash5762 2007
[5] A A Ebert and H B Gottlieb ldquoInfrared spectra of organiccompounds exhibiting polymorphismrdquo Journal of the AmericanChemical Society vol 74 no 11 pp 2806ndash2810 1952
[6] K Wihksne and A E Newkirk ldquoElectrical conductivities of 120572-and 120573-phthalocyaninerdquo Journal of Chemical Physics vol 34 pp2184ndash2185 1961
[7] M Kozlik S Paulke M Gruenewald R Forker and T FritzldquoDetermination of the optical constants of 120572- and 120573-zinc (II)-phthalocyanine filmsrdquo Organic Electronics vol 13 no 12 pp3291ndash3295 2012
[8] F W Karasek and J C Decius ldquoObservations concerningpolymorphic crystalline modifications of the phthalocyaninesrdquoJournal of the American Chemical Society vol 74 no 18 pp4716ndash4717 1952
[9] S Kment P Kluson M Drobek et al ldquoPreparation of thinphthalocyanine layers and their structural and absorptionpropertiesrdquoThin Solid Films vol 517 no 17 pp 5274ndash5279 2009
[10] L Gaffo M R Cordeiro A R Freitas W C Moreira E MGirotto and V Zucolotto ldquoThe effects of temperature on themolecular orientation of zinc phthalocyanine filmsrdquo Journal ofMaterials Science vol 45 no 5 pp 1366ndash1370 2010
[11] H Proehl R Nitsche T Dienel K Leo and T Fritz ldquoIn situdifferential reflectance spectroscopy of thin crystalline films ofPTCDA on different substratesrdquo Physical Review B vol 71 no16 Article ID 165207 14 pages 2005
[12] R Forker and T Fritz ldquoOptical differential reflectance spec-troscopy of ultrathin epitaxial organic filmsrdquo Physical ChemistryChemical Physics vol 11 no 13 pp 2142ndash2155 2009
[13] R Forker M Gruenewald and T Fritz ldquoOptical differentialreflectance spectroscopy on thin molecular filmsrdquo AnnualReports on the Progress of Chemistry C vol 108 pp 34ndash68 2012
[14] E Centurioni ldquoGeneralized matrix method for calculation ofinternal light energy flux in mixed coherent and incoherentmultilayersrdquoApplied Optics vol 44 no 35 pp 7532ndash7539 2005
[15] C C Katsidis and D I Siapkas ldquoGeneral transfer-matrixmethod for optical multilayer systems with coherent partiallycoherent and incoherent interferencerdquo Applied Optics vol 41no 19 pp 3978ndash3987 2002
[16] T Fritz J Hahn and H Bottcher ldquoDetermination of the opticalconstants of evaporated dye layersrdquo Thin Solid Films vol 170no 2 pp 249ndash257 1989
[17] R Nitsche and T Fritz ldquoPrecise determination of the complexoptical constant of micardquo Applied Optics vol 43 no 16 pp3263ndash3270 2004
[18] C Schunemann C Elschner A A Levin M LevichkovaK Leo and M Riede ldquoZinc phthalocyaninemdashinfluence ofsubstrate temperature film thickness and kind of substrate onthe morphologyrdquo Thin Solid Films vol 519 no 11 pp 3939ndash3945 2011
[19] A B Djurisic C Y Kwong T W Lau et al ldquoOptical propertiesof copper phthalocyaninerdquo Optics Communications vol 205no 1ndash3 pp 155ndash162 2002
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ThermodynamicsJournal of
2 Dataset Papers in Physics
0
02
04
06
08
1
15 2 25 3 35 4 45 5
Exp Fit
Tran
smitt
ance
900 600 300
Wavelength (nm)Re
sidua
ls
Energy (eV)
001
minus001
150 nm120 nm90 nm60 nm30 nm
(a)
900 600 300
Wavelength (nm)
0
02
04
06
08
1
Tran
smitt
ance
Resid
uals
002minus002
15 2 25 3 35 4 45 5
Exp Fit
Energy (eV)
150 nm120 nm90 nm60 nm30 nm
(b)
Figure 1 Experimental dataset (open symbols) consisting of (a) 5 samples of 120572-ZnPc and (b) 5 samples of 120573-ZnPc with various nominalthicknesses characterized by one transmittance curve each and the curves which were fitted with a single set of optical constants used forall layer thicknesses (solid line) In the lower part the residuals 119879th minus 119879exp of the fitting process are shown For the sake of clarity subsequentresidual spectra are displayed with a vertical offset The insets show the respective scale bars for the residuals The nominal film thicknessesare given
of the thin film where 119899(119864) and 119896(119864) denote the photon-energy-dependent refractive index and extinction coefficientrespectively
The determination of the optical constants is possible bymeans of a simultaneous analysis of transmission (T) andreflectance (R) spectra However here the reflectance datawere replaced by differential reflectance spectra (DRS) [11ndash13] Thereby the need for a calibrated mirror can be avoidedIn the following the basic ideas of the numerical algorithmwill be explained In order to interpret the measured opticalspectra of ZnPc thin films the numerical treatment is basedon a layer model consisting of the substrate and the organicthin film as well We used the generalized matrix formalismbased on the Fresnel formulas for mixed coherent and inco-herent layers as outlined in [14] In order to improve our layermodel we analyzed the interfaces by non-contact atomicforcemicroscopy (nc-AFM) [7] Accordingly the root-mean-square (rms) roughness (sometimes also denoted by thesymbol 119877
119902
) of as-deposited as well as annealed films of ZnPcwas found to be small but not insignificant with respect to thefilm thickness 119889 (rms119889 lt 20 for 120572-ZnPc and rms119889 lt 5for 120573-ZnPc) Hence for an accurate determination of the
optical constants the values obtained for the surface rough-ness at the air-to-ZnPc interface have to be taken intoaccount This was done by modified Fresnel coefficientsconsidering only partial coherence due to phase differences ofthe transmitted and reflected beams by Gaussian-distributedirregularities as outlined in [15] Because of the azimuthalorientation of the grains the in-plane component of theoptical anisotropy can be neglectedThe substrate was treatedas incoherent due to its rather large thickness (063mm) withrespect to the coherence length of the light This means thatwe indeed account for multiple reflections at both substrateinterfaces but internal interference effects do not contributeto the signal An optical characterization of the quartz glasssubstrate used was done by transmission measurements inthe UV visual and near-infrared spectral region in order toextract the refractive index individually assuming negligibleabsorption (119896 = 0)
As a matter of fact no dispersion model for ZnPc isrequired in the calculation Accordingly the algorithm startswith a set of optical constants that is the refractive index119899(1198641
119864119894
119864119873
) and the extinction coefficient 119896(1198641
119864119894
119864119873
) each consisting of 119873 points to be fitted to
Dataset Papers in Physics 3
900 600 300
Wavelength (nm)
15 2 25 3 35 4 45 5Energy (eV)
DRS
0
0
0
0
0
Resid
uals
1
minus1
01minus01
Exp Fit
150 nm120 nm90 nm60 nm30 nm
(a)
900 600 300
Wavelength (nm)
15 2 25 3 35 4 45 5Energy (eV)
DRS
0
0
0
0
0
0
Resid
uals
02
minus02
1
minus1
Exp Fit
150 nm120 nm90 nm60 nm30 nm
(b)
Figure 2 DRS signal (open symbols) of (a) 120572-ZnPc and (b) 120573-ZnPc and the fitted curves (solid lines) In the lower part the residuals of thefitting process are shown For the sake of clarity the spectra are displayed with a vertical offset The insets show the respective scale bars
the experimental data In this work the energy interval from12 eV to 50 eVwith a step size of 001 eV results in an119873of 381If only one pair of transmission and differential reflectancespectra is used for the extraction of the optical constants 119899and 119896 then the film thickness needs to be specified preciselyto prevent the algorithm to produce large errors in the opticalconstants or even to get stuck in a nonphysical solutionSeveral optical spectra which are not necessarily of the sameoptical quantity analyzed in parallel using the same values forthe refractive index 119899(119864) and the extinction coefficient 119896(119864) ofthe thin film for all spectra were used to overcome this issueas suggested in [16] Consequently five samples with nominalthicknesses of 30 nm 60 nm 90 nm 120 nm and 150 nmrespectively were measured (nominal thicknesses beingdetermined with a quartz crystal microbalance) The objec-tive function to be minimized is
120575 = sum
119895
119873
sum
119894=1
119860(119895)
(119864119894
)
times 119883(119895)
th (119899 (119864119894) 119896 (119864119894)) minus 119883(119895)
exp (119864119894)2
119899 119896 variation997888997888997888997888997888997888997888997888997888997888rarr min
(1)
where119883(119895)th denotes any calculated quantity (eg transmissionor DRS) to be fitted to the respective experimental data119883(119895)exp
The index 119895 is used to distinguish between the differentsamples with different thicknesses Each signal of T and DRSwas weighted by a factor 119860(119895)(119864) as described in [17] in orderto equalize the information 119883(119895)(119864) from all spectra havingoriginally differentmagnitudes119860(119895)(119864) is calculated from theminimal (119899 = 1 119896 = 0) and maximal (119899 = 3 119896 = 1) valuesof the refractive index and extinction coefficient expected forphthalocyanine thin films [16] The advantage of this proce-dure is that the layer thickness can be optimized as well usingthe nominal thicknesses as starting values By doing so it isimportant to cover an appropriate thickness range of layersfitted simultaneously as only thickness-dependent internalinterference effects contribute significant new information tothe fitting procedure Moreover it was found that the fit isthen rather robust against different starting values for thefilm thickness even if they are far from real The rms valueswere treated as fitting parameters likewise except the firstrms value which belongs to the 30 nm ZnPc film where nosignificant gradient in the objective function was found Thefit itself was carried out by means of a Levenberg-Marquardtalgorithm
Figures 1 and 2 show the fitted spectra for both phases ofZnPc as well as the corresponding residuals of the fit for thetransmittance and the DRS signals respectively In Figure 3
4 Dataset Papers in Physics
Table 1 Nominal and optimized values of film thickness and rms values of the samples used for the determination of optical constants Theerrors given are statistical errors from the fitting procedure
Nominal thickness (nm) 120572-ZnPc 120573-ZnPcOptimized thickness (nm) rms (nm) Optimized thickness (nm) rms (nm)
30 3695 plusmn 003 11 plusmn 03 3615 plusmn 005 mdash60 6530 plusmn 004 31 plusmn 02 6190 plusmn 007 54 plusmn 02
90 9663 plusmn 004 77 plusmn 01 9465 plusmn 008 45 plusmn 01
120 13215 plusmn 005 106 plusmn 01 12909 plusmn 007 59 plusmn 01
150 16890 plusmn 007 132 plusmn 01 16788 plusmn 007 56 plusmn 01
the resulting spectra of the optical constants for 120572-ZnPcand 120573-ZnPc are shown Furthermore the optimized filmthicknesses and respective rms values including the standarddeviations of the fit are shown in Table 1
The optical constants for 120572-ZnPc and 120573-ZnPc thin filmsobtained reproduce the spectral measurements very nicelyAs one can see the residuals are very small compared to thetransmission data The edge at 350 nm (354 eV) is caused bythe internal light source changeover of the spectrophotome-ter used but is smaller than the mean residuals and thereforehas no significant influence
The results were checked afterwards for Kramers-Kronigconsistency As described by Nitsche et al [17] the integralcan be split into an additive offset which is energy indepen-dent and an integral the over important region (12 eV to26 eV energetically lowest optical absorption band) whichshows the spectral characteristics to be analyzed In thisregion model-free Kramers-Kronig consistency was con-firmedThe numerically obtained rms values are in very goodagreement with those from our own nc-AFM images [7]and those presented in [18] Without considering the surfaceroughness the fit is less suitable which results in slightly dif-ferent optical constants especially in the ultraviolet spectralregion Our data of 120572-ZnPc compare favorably with thoseof the almost identical molecule copper(II)-phthalocyanine(CuPc 120572-phase) from [16 19]
3 Dataset Description
The dataset associated with this Dataset Paper consists of 5items which are described as follows
Dataset Item 1 (Spectra) Spectra of 5 samples of 120572-ZnPcwith various nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves whichwere fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sake ofclarity subsequent residual spectra are displayed with a ver-tical offset
Dataset Item 2 (Spectra) Spectra of 5 samples of120573-ZnPcwithvarious nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves which
9001200 600 300
Wavelength (nm)
03
252
151
05
0
252
151
05
119899119896
119899119896
151 2 25 3 35 4 45 5Energy (eV)
Std dev (times5)
Figure 3 Spectra of refractive index 119899 and extinction coefficient 119896 of120572- (top) and 120573- (bottom) ZnPc respectively The standard deviation(statistical errors from the fitting procedure enlarged 5 times) isindicated by the reddish error margin
were fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sakeof clarity subsequent residual spectra are displayed with avertical offset
Dataset Item 3 (Spectra) DRS signal (open symbols) of 120572-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 4 (Spectra) DRS signal (open symbols) of 120573-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 5 (Spectra) Spectra of refractive index 119899 andextinction coefficient 119896 of 120572- (top) and 120573- (bottom) ZnPcrespectively The standard deviation (statistical errors fromthe fitting procedure enlarged 5 times) is indicated by thereddish error margin
Dataset Papers in Physics 5
4 Concluding Remarks
Different crystalline phases of ZnPc namely 120572-ZnPc and120573-ZnPc have been characterized optically via UV-Vis spec-troscopy Reliable data for the optical constants of bothzinc(II)-phthalocyanine phases could be determined whenthe surface roughness was taken into account Kramers-Kronig consistency was confirmed numerically afterwards
Dataset Availability
The dataset associated with this Dataset Paper is dedicated tothe public domain using the CC0 waiver and is available athttpdxdoiorg1011552013926470dataset
Disclosure
The authors do not have a direct financial relation with thecommercial identitiesmentioned in the paper thatmight leadto conflict of interests for any of the authors
Acknowledgments
The financial support by the Thuringer Ministerium furBildung Wissenschaft und Kultur Grant no B515-10030and by the Deutsche Forschungsgemeinschaft (DFG) Grantnos FR8759 and FR87511 is gratefully acknowledged Theauthors thank Prof Dr Carsten Ronning for making hisequipment for optical spectroscopy available to them
References
[1] I Kim H M Haverinen Z Wang et al ldquoEfficient organicsolar cells based on planar metallophthalocyaninesrdquo Chemistryof Materials vol 21 pp 4256ndash4260 2009
[2] C Florica I Arghir and L Ion ldquoProduction and characteriza-tion of CdTe wire arrays for hybrid inorganicorganic photo-voltaic cellsrdquoDigest Journal of Nanomaterials and Biostructuresvol 6 no 1 pp 21ndash27 2011
[3] L-C Chen and B-H Liu ldquoPorous silicon layer patterned fromanodic aluminum oxide and application in ZnPc hybrid solarcellrdquo Electrochemical and Solid-State Letters vol 13 no 4 ppH108ndashH111 2010
[4] S Bereznev R Koeppe I Konovalov et al ldquoHybrid solar cellsbased onCuInS
2
and organic buffer-sensitizer layersrdquoThin SolidFilms vol 515 no 15 pp 5759ndash5762 2007
[5] A A Ebert and H B Gottlieb ldquoInfrared spectra of organiccompounds exhibiting polymorphismrdquo Journal of the AmericanChemical Society vol 74 no 11 pp 2806ndash2810 1952
[6] K Wihksne and A E Newkirk ldquoElectrical conductivities of 120572-and 120573-phthalocyaninerdquo Journal of Chemical Physics vol 34 pp2184ndash2185 1961
[7] M Kozlik S Paulke M Gruenewald R Forker and T FritzldquoDetermination of the optical constants of 120572- and 120573-zinc (II)-phthalocyanine filmsrdquo Organic Electronics vol 13 no 12 pp3291ndash3295 2012
[8] F W Karasek and J C Decius ldquoObservations concerningpolymorphic crystalline modifications of the phthalocyaninesrdquoJournal of the American Chemical Society vol 74 no 18 pp4716ndash4717 1952
[9] S Kment P Kluson M Drobek et al ldquoPreparation of thinphthalocyanine layers and their structural and absorptionpropertiesrdquoThin Solid Films vol 517 no 17 pp 5274ndash5279 2009
[10] L Gaffo M R Cordeiro A R Freitas W C Moreira E MGirotto and V Zucolotto ldquoThe effects of temperature on themolecular orientation of zinc phthalocyanine filmsrdquo Journal ofMaterials Science vol 45 no 5 pp 1366ndash1370 2010
[11] H Proehl R Nitsche T Dienel K Leo and T Fritz ldquoIn situdifferential reflectance spectroscopy of thin crystalline films ofPTCDA on different substratesrdquo Physical Review B vol 71 no16 Article ID 165207 14 pages 2005
[12] R Forker and T Fritz ldquoOptical differential reflectance spec-troscopy of ultrathin epitaxial organic filmsrdquo Physical ChemistryChemical Physics vol 11 no 13 pp 2142ndash2155 2009
[13] R Forker M Gruenewald and T Fritz ldquoOptical differentialreflectance spectroscopy on thin molecular filmsrdquo AnnualReports on the Progress of Chemistry C vol 108 pp 34ndash68 2012
[14] E Centurioni ldquoGeneralized matrix method for calculation ofinternal light energy flux in mixed coherent and incoherentmultilayersrdquoApplied Optics vol 44 no 35 pp 7532ndash7539 2005
[15] C C Katsidis and D I Siapkas ldquoGeneral transfer-matrixmethod for optical multilayer systems with coherent partiallycoherent and incoherent interferencerdquo Applied Optics vol 41no 19 pp 3978ndash3987 2002
[16] T Fritz J Hahn and H Bottcher ldquoDetermination of the opticalconstants of evaporated dye layersrdquo Thin Solid Films vol 170no 2 pp 249ndash257 1989
[17] R Nitsche and T Fritz ldquoPrecise determination of the complexoptical constant of micardquo Applied Optics vol 43 no 16 pp3263ndash3270 2004
[18] C Schunemann C Elschner A A Levin M LevichkovaK Leo and M Riede ldquoZinc phthalocyaninemdashinfluence ofsubstrate temperature film thickness and kind of substrate onthe morphologyrdquo Thin Solid Films vol 519 no 11 pp 3939ndash3945 2011
[19] A B Djurisic C Y Kwong T W Lau et al ldquoOptical propertiesof copper phthalocyaninerdquo Optics Communications vol 205no 1ndash3 pp 155ndash162 2002
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
Dataset Papers in Physics 3
900 600 300
Wavelength (nm)
15 2 25 3 35 4 45 5Energy (eV)
DRS
0
0
0
0
0
Resid
uals
1
minus1
01minus01
Exp Fit
150 nm120 nm90 nm60 nm30 nm
(a)
900 600 300
Wavelength (nm)
15 2 25 3 35 4 45 5Energy (eV)
DRS
0
0
0
0
0
0
Resid
uals
02
minus02
1
minus1
Exp Fit
150 nm120 nm90 nm60 nm30 nm
(b)
Figure 2 DRS signal (open symbols) of (a) 120572-ZnPc and (b) 120573-ZnPc and the fitted curves (solid lines) In the lower part the residuals of thefitting process are shown For the sake of clarity the spectra are displayed with a vertical offset The insets show the respective scale bars
the experimental data In this work the energy interval from12 eV to 50 eVwith a step size of 001 eV results in an119873of 381If only one pair of transmission and differential reflectancespectra is used for the extraction of the optical constants 119899and 119896 then the film thickness needs to be specified preciselyto prevent the algorithm to produce large errors in the opticalconstants or even to get stuck in a nonphysical solutionSeveral optical spectra which are not necessarily of the sameoptical quantity analyzed in parallel using the same values forthe refractive index 119899(119864) and the extinction coefficient 119896(119864) ofthe thin film for all spectra were used to overcome this issueas suggested in [16] Consequently five samples with nominalthicknesses of 30 nm 60 nm 90 nm 120 nm and 150 nmrespectively were measured (nominal thicknesses beingdetermined with a quartz crystal microbalance) The objec-tive function to be minimized is
120575 = sum
119895
119873
sum
119894=1
119860(119895)
(119864119894
)
times 119883(119895)
th (119899 (119864119894) 119896 (119864119894)) minus 119883(119895)
exp (119864119894)2
119899 119896 variation997888997888997888997888997888997888997888997888997888997888rarr min
(1)
where119883(119895)th denotes any calculated quantity (eg transmissionor DRS) to be fitted to the respective experimental data119883(119895)exp
The index 119895 is used to distinguish between the differentsamples with different thicknesses Each signal of T and DRSwas weighted by a factor 119860(119895)(119864) as described in [17] in orderto equalize the information 119883(119895)(119864) from all spectra havingoriginally differentmagnitudes119860(119895)(119864) is calculated from theminimal (119899 = 1 119896 = 0) and maximal (119899 = 3 119896 = 1) valuesof the refractive index and extinction coefficient expected forphthalocyanine thin films [16] The advantage of this proce-dure is that the layer thickness can be optimized as well usingthe nominal thicknesses as starting values By doing so it isimportant to cover an appropriate thickness range of layersfitted simultaneously as only thickness-dependent internalinterference effects contribute significant new information tothe fitting procedure Moreover it was found that the fit isthen rather robust against different starting values for thefilm thickness even if they are far from real The rms valueswere treated as fitting parameters likewise except the firstrms value which belongs to the 30 nm ZnPc film where nosignificant gradient in the objective function was found Thefit itself was carried out by means of a Levenberg-Marquardtalgorithm
Figures 1 and 2 show the fitted spectra for both phases ofZnPc as well as the corresponding residuals of the fit for thetransmittance and the DRS signals respectively In Figure 3
4 Dataset Papers in Physics
Table 1 Nominal and optimized values of film thickness and rms values of the samples used for the determination of optical constants Theerrors given are statistical errors from the fitting procedure
Nominal thickness (nm) 120572-ZnPc 120573-ZnPcOptimized thickness (nm) rms (nm) Optimized thickness (nm) rms (nm)
30 3695 plusmn 003 11 plusmn 03 3615 plusmn 005 mdash60 6530 plusmn 004 31 plusmn 02 6190 plusmn 007 54 plusmn 02
90 9663 plusmn 004 77 plusmn 01 9465 plusmn 008 45 plusmn 01
120 13215 plusmn 005 106 plusmn 01 12909 plusmn 007 59 plusmn 01
150 16890 plusmn 007 132 plusmn 01 16788 plusmn 007 56 plusmn 01
the resulting spectra of the optical constants for 120572-ZnPcand 120573-ZnPc are shown Furthermore the optimized filmthicknesses and respective rms values including the standarddeviations of the fit are shown in Table 1
The optical constants for 120572-ZnPc and 120573-ZnPc thin filmsobtained reproduce the spectral measurements very nicelyAs one can see the residuals are very small compared to thetransmission data The edge at 350 nm (354 eV) is caused bythe internal light source changeover of the spectrophotome-ter used but is smaller than the mean residuals and thereforehas no significant influence
The results were checked afterwards for Kramers-Kronigconsistency As described by Nitsche et al [17] the integralcan be split into an additive offset which is energy indepen-dent and an integral the over important region (12 eV to26 eV energetically lowest optical absorption band) whichshows the spectral characteristics to be analyzed In thisregion model-free Kramers-Kronig consistency was con-firmedThe numerically obtained rms values are in very goodagreement with those from our own nc-AFM images [7]and those presented in [18] Without considering the surfaceroughness the fit is less suitable which results in slightly dif-ferent optical constants especially in the ultraviolet spectralregion Our data of 120572-ZnPc compare favorably with thoseof the almost identical molecule copper(II)-phthalocyanine(CuPc 120572-phase) from [16 19]
3 Dataset Description
The dataset associated with this Dataset Paper consists of 5items which are described as follows
Dataset Item 1 (Spectra) Spectra of 5 samples of 120572-ZnPcwith various nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves whichwere fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sake ofclarity subsequent residual spectra are displayed with a ver-tical offset
Dataset Item 2 (Spectra) Spectra of 5 samples of120573-ZnPcwithvarious nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves which
9001200 600 300
Wavelength (nm)
03
252
151
05
0
252
151
05
119899119896
119899119896
151 2 25 3 35 4 45 5Energy (eV)
Std dev (times5)
Figure 3 Spectra of refractive index 119899 and extinction coefficient 119896 of120572- (top) and 120573- (bottom) ZnPc respectively The standard deviation(statistical errors from the fitting procedure enlarged 5 times) isindicated by the reddish error margin
were fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sakeof clarity subsequent residual spectra are displayed with avertical offset
Dataset Item 3 (Spectra) DRS signal (open symbols) of 120572-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 4 (Spectra) DRS signal (open symbols) of 120573-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 5 (Spectra) Spectra of refractive index 119899 andextinction coefficient 119896 of 120572- (top) and 120573- (bottom) ZnPcrespectively The standard deviation (statistical errors fromthe fitting procedure enlarged 5 times) is indicated by thereddish error margin
Dataset Papers in Physics 5
4 Concluding Remarks
Different crystalline phases of ZnPc namely 120572-ZnPc and120573-ZnPc have been characterized optically via UV-Vis spec-troscopy Reliable data for the optical constants of bothzinc(II)-phthalocyanine phases could be determined whenthe surface roughness was taken into account Kramers-Kronig consistency was confirmed numerically afterwards
Dataset Availability
The dataset associated with this Dataset Paper is dedicated tothe public domain using the CC0 waiver and is available athttpdxdoiorg1011552013926470dataset
Disclosure
The authors do not have a direct financial relation with thecommercial identitiesmentioned in the paper thatmight leadto conflict of interests for any of the authors
Acknowledgments
The financial support by the Thuringer Ministerium furBildung Wissenschaft und Kultur Grant no B515-10030and by the Deutsche Forschungsgemeinschaft (DFG) Grantnos FR8759 and FR87511 is gratefully acknowledged Theauthors thank Prof Dr Carsten Ronning for making hisequipment for optical spectroscopy available to them
References
[1] I Kim H M Haverinen Z Wang et al ldquoEfficient organicsolar cells based on planar metallophthalocyaninesrdquo Chemistryof Materials vol 21 pp 4256ndash4260 2009
[2] C Florica I Arghir and L Ion ldquoProduction and characteriza-tion of CdTe wire arrays for hybrid inorganicorganic photo-voltaic cellsrdquoDigest Journal of Nanomaterials and Biostructuresvol 6 no 1 pp 21ndash27 2011
[3] L-C Chen and B-H Liu ldquoPorous silicon layer patterned fromanodic aluminum oxide and application in ZnPc hybrid solarcellrdquo Electrochemical and Solid-State Letters vol 13 no 4 ppH108ndashH111 2010
[4] S Bereznev R Koeppe I Konovalov et al ldquoHybrid solar cellsbased onCuInS
2
and organic buffer-sensitizer layersrdquoThin SolidFilms vol 515 no 15 pp 5759ndash5762 2007
[5] A A Ebert and H B Gottlieb ldquoInfrared spectra of organiccompounds exhibiting polymorphismrdquo Journal of the AmericanChemical Society vol 74 no 11 pp 2806ndash2810 1952
[6] K Wihksne and A E Newkirk ldquoElectrical conductivities of 120572-and 120573-phthalocyaninerdquo Journal of Chemical Physics vol 34 pp2184ndash2185 1961
[7] M Kozlik S Paulke M Gruenewald R Forker and T FritzldquoDetermination of the optical constants of 120572- and 120573-zinc (II)-phthalocyanine filmsrdquo Organic Electronics vol 13 no 12 pp3291ndash3295 2012
[8] F W Karasek and J C Decius ldquoObservations concerningpolymorphic crystalline modifications of the phthalocyaninesrdquoJournal of the American Chemical Society vol 74 no 18 pp4716ndash4717 1952
[9] S Kment P Kluson M Drobek et al ldquoPreparation of thinphthalocyanine layers and their structural and absorptionpropertiesrdquoThin Solid Films vol 517 no 17 pp 5274ndash5279 2009
[10] L Gaffo M R Cordeiro A R Freitas W C Moreira E MGirotto and V Zucolotto ldquoThe effects of temperature on themolecular orientation of zinc phthalocyanine filmsrdquo Journal ofMaterials Science vol 45 no 5 pp 1366ndash1370 2010
[11] H Proehl R Nitsche T Dienel K Leo and T Fritz ldquoIn situdifferential reflectance spectroscopy of thin crystalline films ofPTCDA on different substratesrdquo Physical Review B vol 71 no16 Article ID 165207 14 pages 2005
[12] R Forker and T Fritz ldquoOptical differential reflectance spec-troscopy of ultrathin epitaxial organic filmsrdquo Physical ChemistryChemical Physics vol 11 no 13 pp 2142ndash2155 2009
[13] R Forker M Gruenewald and T Fritz ldquoOptical differentialreflectance spectroscopy on thin molecular filmsrdquo AnnualReports on the Progress of Chemistry C vol 108 pp 34ndash68 2012
[14] E Centurioni ldquoGeneralized matrix method for calculation ofinternal light energy flux in mixed coherent and incoherentmultilayersrdquoApplied Optics vol 44 no 35 pp 7532ndash7539 2005
[15] C C Katsidis and D I Siapkas ldquoGeneral transfer-matrixmethod for optical multilayer systems with coherent partiallycoherent and incoherent interferencerdquo Applied Optics vol 41no 19 pp 3978ndash3987 2002
[16] T Fritz J Hahn and H Bottcher ldquoDetermination of the opticalconstants of evaporated dye layersrdquo Thin Solid Films vol 170no 2 pp 249ndash257 1989
[17] R Nitsche and T Fritz ldquoPrecise determination of the complexoptical constant of micardquo Applied Optics vol 43 no 16 pp3263ndash3270 2004
[18] C Schunemann C Elschner A A Levin M LevichkovaK Leo and M Riede ldquoZinc phthalocyaninemdashinfluence ofsubstrate temperature film thickness and kind of substrate onthe morphologyrdquo Thin Solid Films vol 519 no 11 pp 3939ndash3945 2011
[19] A B Djurisic C Y Kwong T W Lau et al ldquoOptical propertiesof copper phthalocyaninerdquo Optics Communications vol 205no 1ndash3 pp 155ndash162 2002
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
4 Dataset Papers in Physics
Table 1 Nominal and optimized values of film thickness and rms values of the samples used for the determination of optical constants Theerrors given are statistical errors from the fitting procedure
Nominal thickness (nm) 120572-ZnPc 120573-ZnPcOptimized thickness (nm) rms (nm) Optimized thickness (nm) rms (nm)
30 3695 plusmn 003 11 plusmn 03 3615 plusmn 005 mdash60 6530 plusmn 004 31 plusmn 02 6190 plusmn 007 54 plusmn 02
90 9663 plusmn 004 77 plusmn 01 9465 plusmn 008 45 plusmn 01
120 13215 plusmn 005 106 plusmn 01 12909 plusmn 007 59 plusmn 01
150 16890 plusmn 007 132 plusmn 01 16788 plusmn 007 56 plusmn 01
the resulting spectra of the optical constants for 120572-ZnPcand 120573-ZnPc are shown Furthermore the optimized filmthicknesses and respective rms values including the standarddeviations of the fit are shown in Table 1
The optical constants for 120572-ZnPc and 120573-ZnPc thin filmsobtained reproduce the spectral measurements very nicelyAs one can see the residuals are very small compared to thetransmission data The edge at 350 nm (354 eV) is caused bythe internal light source changeover of the spectrophotome-ter used but is smaller than the mean residuals and thereforehas no significant influence
The results were checked afterwards for Kramers-Kronigconsistency As described by Nitsche et al [17] the integralcan be split into an additive offset which is energy indepen-dent and an integral the over important region (12 eV to26 eV energetically lowest optical absorption band) whichshows the spectral characteristics to be analyzed In thisregion model-free Kramers-Kronig consistency was con-firmedThe numerically obtained rms values are in very goodagreement with those from our own nc-AFM images [7]and those presented in [18] Without considering the surfaceroughness the fit is less suitable which results in slightly dif-ferent optical constants especially in the ultraviolet spectralregion Our data of 120572-ZnPc compare favorably with thoseof the almost identical molecule copper(II)-phthalocyanine(CuPc 120572-phase) from [16 19]
3 Dataset Description
The dataset associated with this Dataset Paper consists of 5items which are described as follows
Dataset Item 1 (Spectra) Spectra of 5 samples of 120572-ZnPcwith various nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves whichwere fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sake ofclarity subsequent residual spectra are displayed with a ver-tical offset
Dataset Item 2 (Spectra) Spectra of 5 samples of120573-ZnPcwithvarious nominal thicknesses characterized by one trans-mittance curve each (open symbols) and the curves which
9001200 600 300
Wavelength (nm)
03
252
151
05
0
252
151
05
119899119896
119899119896
151 2 25 3 35 4 45 5Energy (eV)
Std dev (times5)
Figure 3 Spectra of refractive index 119899 and extinction coefficient 119896 of120572- (top) and 120573- (bottom) ZnPc respectively The standard deviation(statistical errors from the fitting procedure enlarged 5 times) isindicated by the reddish error margin
were fitted with a single set of optical constants used for alllayer thicknesses (solid line) In the lower part the residuals119879th minus 119879exp of the fitting process are shown For the sakeof clarity subsequent residual spectra are displayed with avertical offset
Dataset Item 3 (Spectra) DRS signal (open symbols) of 120572-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 4 (Spectra) DRS signal (open symbols) of 120573-ZnPc and the fitted curves (solid lines) In the lower partthe residuals of the fitting process are shown For the sake ofclarity the spectra are displayed with a vertical offset
Dataset Item 5 (Spectra) Spectra of refractive index 119899 andextinction coefficient 119896 of 120572- (top) and 120573- (bottom) ZnPcrespectively The standard deviation (statistical errors fromthe fitting procedure enlarged 5 times) is indicated by thereddish error margin
Dataset Papers in Physics 5
4 Concluding Remarks
Different crystalline phases of ZnPc namely 120572-ZnPc and120573-ZnPc have been characterized optically via UV-Vis spec-troscopy Reliable data for the optical constants of bothzinc(II)-phthalocyanine phases could be determined whenthe surface roughness was taken into account Kramers-Kronig consistency was confirmed numerically afterwards
Dataset Availability
The dataset associated with this Dataset Paper is dedicated tothe public domain using the CC0 waiver and is available athttpdxdoiorg1011552013926470dataset
Disclosure
The authors do not have a direct financial relation with thecommercial identitiesmentioned in the paper thatmight leadto conflict of interests for any of the authors
Acknowledgments
The financial support by the Thuringer Ministerium furBildung Wissenschaft und Kultur Grant no B515-10030and by the Deutsche Forschungsgemeinschaft (DFG) Grantnos FR8759 and FR87511 is gratefully acknowledged Theauthors thank Prof Dr Carsten Ronning for making hisequipment for optical spectroscopy available to them
References
[1] I Kim H M Haverinen Z Wang et al ldquoEfficient organicsolar cells based on planar metallophthalocyaninesrdquo Chemistryof Materials vol 21 pp 4256ndash4260 2009
[2] C Florica I Arghir and L Ion ldquoProduction and characteriza-tion of CdTe wire arrays for hybrid inorganicorganic photo-voltaic cellsrdquoDigest Journal of Nanomaterials and Biostructuresvol 6 no 1 pp 21ndash27 2011
[3] L-C Chen and B-H Liu ldquoPorous silicon layer patterned fromanodic aluminum oxide and application in ZnPc hybrid solarcellrdquo Electrochemical and Solid-State Letters vol 13 no 4 ppH108ndashH111 2010
[4] S Bereznev R Koeppe I Konovalov et al ldquoHybrid solar cellsbased onCuInS
2
and organic buffer-sensitizer layersrdquoThin SolidFilms vol 515 no 15 pp 5759ndash5762 2007
[5] A A Ebert and H B Gottlieb ldquoInfrared spectra of organiccompounds exhibiting polymorphismrdquo Journal of the AmericanChemical Society vol 74 no 11 pp 2806ndash2810 1952
[6] K Wihksne and A E Newkirk ldquoElectrical conductivities of 120572-and 120573-phthalocyaninerdquo Journal of Chemical Physics vol 34 pp2184ndash2185 1961
[7] M Kozlik S Paulke M Gruenewald R Forker and T FritzldquoDetermination of the optical constants of 120572- and 120573-zinc (II)-phthalocyanine filmsrdquo Organic Electronics vol 13 no 12 pp3291ndash3295 2012
[8] F W Karasek and J C Decius ldquoObservations concerningpolymorphic crystalline modifications of the phthalocyaninesrdquoJournal of the American Chemical Society vol 74 no 18 pp4716ndash4717 1952
[9] S Kment P Kluson M Drobek et al ldquoPreparation of thinphthalocyanine layers and their structural and absorptionpropertiesrdquoThin Solid Films vol 517 no 17 pp 5274ndash5279 2009
[10] L Gaffo M R Cordeiro A R Freitas W C Moreira E MGirotto and V Zucolotto ldquoThe effects of temperature on themolecular orientation of zinc phthalocyanine filmsrdquo Journal ofMaterials Science vol 45 no 5 pp 1366ndash1370 2010
[11] H Proehl R Nitsche T Dienel K Leo and T Fritz ldquoIn situdifferential reflectance spectroscopy of thin crystalline films ofPTCDA on different substratesrdquo Physical Review B vol 71 no16 Article ID 165207 14 pages 2005
[12] R Forker and T Fritz ldquoOptical differential reflectance spec-troscopy of ultrathin epitaxial organic filmsrdquo Physical ChemistryChemical Physics vol 11 no 13 pp 2142ndash2155 2009
[13] R Forker M Gruenewald and T Fritz ldquoOptical differentialreflectance spectroscopy on thin molecular filmsrdquo AnnualReports on the Progress of Chemistry C vol 108 pp 34ndash68 2012
[14] E Centurioni ldquoGeneralized matrix method for calculation ofinternal light energy flux in mixed coherent and incoherentmultilayersrdquoApplied Optics vol 44 no 35 pp 7532ndash7539 2005
[15] C C Katsidis and D I Siapkas ldquoGeneral transfer-matrixmethod for optical multilayer systems with coherent partiallycoherent and incoherent interferencerdquo Applied Optics vol 41no 19 pp 3978ndash3987 2002
[16] T Fritz J Hahn and H Bottcher ldquoDetermination of the opticalconstants of evaporated dye layersrdquo Thin Solid Films vol 170no 2 pp 249ndash257 1989
[17] R Nitsche and T Fritz ldquoPrecise determination of the complexoptical constant of micardquo Applied Optics vol 43 no 16 pp3263ndash3270 2004
[18] C Schunemann C Elschner A A Levin M LevichkovaK Leo and M Riede ldquoZinc phthalocyaninemdashinfluence ofsubstrate temperature film thickness and kind of substrate onthe morphologyrdquo Thin Solid Films vol 519 no 11 pp 3939ndash3945 2011
[19] A B Djurisic C Y Kwong T W Lau et al ldquoOptical propertiesof copper phthalocyaninerdquo Optics Communications vol 205no 1ndash3 pp 155ndash162 2002
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
Dataset Papers in Physics 5
4 Concluding Remarks
Different crystalline phases of ZnPc namely 120572-ZnPc and120573-ZnPc have been characterized optically via UV-Vis spec-troscopy Reliable data for the optical constants of bothzinc(II)-phthalocyanine phases could be determined whenthe surface roughness was taken into account Kramers-Kronig consistency was confirmed numerically afterwards
Dataset Availability
The dataset associated with this Dataset Paper is dedicated tothe public domain using the CC0 waiver and is available athttpdxdoiorg1011552013926470dataset
Disclosure
The authors do not have a direct financial relation with thecommercial identitiesmentioned in the paper thatmight leadto conflict of interests for any of the authors
Acknowledgments
The financial support by the Thuringer Ministerium furBildung Wissenschaft und Kultur Grant no B515-10030and by the Deutsche Forschungsgemeinschaft (DFG) Grantnos FR8759 and FR87511 is gratefully acknowledged Theauthors thank Prof Dr Carsten Ronning for making hisequipment for optical spectroscopy available to them
References
[1] I Kim H M Haverinen Z Wang et al ldquoEfficient organicsolar cells based on planar metallophthalocyaninesrdquo Chemistryof Materials vol 21 pp 4256ndash4260 2009
[2] C Florica I Arghir and L Ion ldquoProduction and characteriza-tion of CdTe wire arrays for hybrid inorganicorganic photo-voltaic cellsrdquoDigest Journal of Nanomaterials and Biostructuresvol 6 no 1 pp 21ndash27 2011
[3] L-C Chen and B-H Liu ldquoPorous silicon layer patterned fromanodic aluminum oxide and application in ZnPc hybrid solarcellrdquo Electrochemical and Solid-State Letters vol 13 no 4 ppH108ndashH111 2010
[4] S Bereznev R Koeppe I Konovalov et al ldquoHybrid solar cellsbased onCuInS
2
and organic buffer-sensitizer layersrdquoThin SolidFilms vol 515 no 15 pp 5759ndash5762 2007
[5] A A Ebert and H B Gottlieb ldquoInfrared spectra of organiccompounds exhibiting polymorphismrdquo Journal of the AmericanChemical Society vol 74 no 11 pp 2806ndash2810 1952
[6] K Wihksne and A E Newkirk ldquoElectrical conductivities of 120572-and 120573-phthalocyaninerdquo Journal of Chemical Physics vol 34 pp2184ndash2185 1961
[7] M Kozlik S Paulke M Gruenewald R Forker and T FritzldquoDetermination of the optical constants of 120572- and 120573-zinc (II)-phthalocyanine filmsrdquo Organic Electronics vol 13 no 12 pp3291ndash3295 2012
[8] F W Karasek and J C Decius ldquoObservations concerningpolymorphic crystalline modifications of the phthalocyaninesrdquoJournal of the American Chemical Society vol 74 no 18 pp4716ndash4717 1952
[9] S Kment P Kluson M Drobek et al ldquoPreparation of thinphthalocyanine layers and their structural and absorptionpropertiesrdquoThin Solid Films vol 517 no 17 pp 5274ndash5279 2009
[10] L Gaffo M R Cordeiro A R Freitas W C Moreira E MGirotto and V Zucolotto ldquoThe effects of temperature on themolecular orientation of zinc phthalocyanine filmsrdquo Journal ofMaterials Science vol 45 no 5 pp 1366ndash1370 2010
[11] H Proehl R Nitsche T Dienel K Leo and T Fritz ldquoIn situdifferential reflectance spectroscopy of thin crystalline films ofPTCDA on different substratesrdquo Physical Review B vol 71 no16 Article ID 165207 14 pages 2005
[12] R Forker and T Fritz ldquoOptical differential reflectance spec-troscopy of ultrathin epitaxial organic filmsrdquo Physical ChemistryChemical Physics vol 11 no 13 pp 2142ndash2155 2009
[13] R Forker M Gruenewald and T Fritz ldquoOptical differentialreflectance spectroscopy on thin molecular filmsrdquo AnnualReports on the Progress of Chemistry C vol 108 pp 34ndash68 2012
[14] E Centurioni ldquoGeneralized matrix method for calculation ofinternal light energy flux in mixed coherent and incoherentmultilayersrdquoApplied Optics vol 44 no 35 pp 7532ndash7539 2005
[15] C C Katsidis and D I Siapkas ldquoGeneral transfer-matrixmethod for optical multilayer systems with coherent partiallycoherent and incoherent interferencerdquo Applied Optics vol 41no 19 pp 3978ndash3987 2002
[16] T Fritz J Hahn and H Bottcher ldquoDetermination of the opticalconstants of evaporated dye layersrdquo Thin Solid Films vol 170no 2 pp 249ndash257 1989
[17] R Nitsche and T Fritz ldquoPrecise determination of the complexoptical constant of micardquo Applied Optics vol 43 no 16 pp3263ndash3270 2004
[18] C Schunemann C Elschner A A Levin M LevichkovaK Leo and M Riede ldquoZinc phthalocyaninemdashinfluence ofsubstrate temperature film thickness and kind of substrate onthe morphologyrdquo Thin Solid Films vol 519 no 11 pp 3939ndash3945 2011
[19] A B Djurisic C Y Kwong T W Lau et al ldquoOptical propertiesof copper phthalocyaninerdquo Optics Communications vol 205no 1ndash3 pp 155ndash162 2002
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
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