Supporting Information · Data collection parameters: 2? range = –60 º, step size = 0.02 °,3 scan speed = 10 second/step. Reproducible dataset of each sample was obtained and

Supporting Information

© Copyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, 2008

Homoleptic Copper(I) Arylthiolates as a New Class of p-Type Charge

Carrier: Structures and Charge Mobility Studies

Chi-Ming Che*,[a,b] Cheng-Hui Li,[a,b] Stephen Sin-Yin Chui,[b] V. A. L. Roy,[b]

Kam-Hung Low[b]

[a] Coordination Chemistry Institute and the State Key Laboratory of Coordination Chemistry, School

of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of

China

[b] Department of Chemistry and HKU-CAS Joint Laboratory on New Materials, The University of

Hong Kong, Pokfulam Road, Hong Kong, China.

Fax: (852) 2857-1586

E-mail (corresponding author): [email protected]

Structure Determination of 1–3 and 6 using Powder Diffraction Data.

a) Sample Preparation and Data Collection: Solids 1–3 and 6 were freshly prepared

and were mechanically ground into fine powders. The powder was side-loaded onto a

glass holder to form a flat surface (ca. 14 mm (diameter) × 0.5 mm (depth)).

Step-scanned powder diffraction data was collected using Bruker D8 Advance ?/?

diffractometer with parallel CuKa (? = 1.5406 Å, rated as 1.6 kW) X-ray radiation via

a Göbel mirror, or Philips APD ?/2? diffractometer with graphite-monochromatized

CuKa (Ni-filtered, rated as 1.6 kW) radiation. After a preliminary data collection, the

mounted sample was unpacked and reloaded onto the same holder to minimize the

systematic errors from the particle statistics and preferred orientation of the solids.

Data collection parameters: 2? range = 3–60 º, step size = 0.02 °, scan speed = 10

second/step. Reproducible dataset of each sample was obtained and the sample

damage by X-ray irradiation was negligible. The phase purity of the solids was

checked by ICDD (International Center fro Diffraction Data, PDF-2 Release 2004)

database match search and the powdered samples were free of known crystalline

impurities.

b) Structure Solution: Preliminary lattice parameters of 1–3 were indexed with the

12–20 low-angle diffraction peaks. Monoclinic unit cell [a = 24.749 Å, b = 14.049 Å, c

= 4.0175 Å, ß = 98.025º, M(20) = 11, F(20) = 19 (0.016, 65)] for 1 was found by

DICVOL04.[a] Indexing the 12 diffraction maxima from the diffractograph of 2 gave a

reduced tetragonal P lattice [a’ = b’ = 12.167(3) Å, c = 3.800(2) Å, V = 562.70 Å3,

M(12) = 49, F(12) = 49 (0.0137,18)]. The true cell length a can be derived by a

geometric transformation [a = v2(a’)2] and the first four diffraction maxima are

indexed as [110], [200], [220] and [310] reflections with a characteristic ratio as

q:v2q:2q:v5q (q = 1/d). The short c-axis of the tetragonal lattice of 2 was subsequently

confirmed by the unit cell refinement as well as the SAED study in this work.

Monoclinic cell [a = 26.1933 Å b = 13.7922 Å c = 4.0718 Å ß = 92.47 º V = 1469.62

Å3] was found in the case of 3 by indexing the first 19 peaks in the 2? range 6-25 º with

the figure merits M(19) = 19.4, F(19) = 38.8 (0.0126, 39). Whereas a tetragonal P

lattice for 6 [a = b = 19.617(3) Å, c = 3.950(1) Å, V = 1520.21 Å3, M(20) = 20, F(20) =

30 (0.0123,54)] was obtained by TREOR90.[b] All initial lattice parameters of 1–3 and

6 were refined by the Pawley fit algorithm.[c] Background coefficients, zero-point, and

profile shape variables were refined together to attain improved profile fitting with

reliability indicators wRp, Rp and ?2 < 10. Probable space group assignment was

performed by a trial-and-error approach, in which the expected systematic absences of

extracted intensities were examined. The most common space group P21/n for 1 and 3

were chosen. Whereas space group P42/n (number 86) was assigned to 2 and 6 because

(i) all observed and indexed peaks in their diffractographs matched with the calculated

Bragg positions, (ii) high occurrence (275 times for P42/n, 213 times for P4/n, 85 times

for P4/ncc, 79 times for P4/nmm) among the common centrosymmetric space groups

appeared in the Cambridge Structural Database (CSD 2005 release). According to their

unit cell volumes, eight formula mass units of [Cu(SR)] in 1–3 and 6 were physically

reasonable for each asymmetric unit. Their starting models were built and written as a

MOL file format by the program ISIS DRAW version 2.14 and later were converted to

sets of fractional coordinates written in a Z-matrix file format by program Babel

(http://www.eyeopen.com/babel/) or OPENBABEL

(http://openbabel.sourceforge.net). Bond distances restraints (Å) were used:

C(sp2/sp3)–H 0.96, C(sp2)–C(sp2) 1.39, C(sp2)–N(sp2) 1.38, N(sp2)–O(sp2) 1.20,

C(sp3)–C(sp3) 1.54, C(sp2)–S 1.78, Cu–S 2.250. The bond angle restraints (º) for

C(sp2)-C(sp2)–C(sp2)/C(sp2)–C(sp2)–S and C(sp3)–C(sp3)–C(sp3) are 120 and 109.5,

respectively. The carbon atoms of the phenyl rings in 1–3 and 6 were constrained into a

regular hexagon. The positions of aromatic hydrogen atoms were added onto their

parent carbon atoms in the idealized geometry. Structure solutions calculations were

initiated by a global optimization of experimental diffraction profiles using simulated

annealing algorithm implemented in the program DASH[d] or parallel tempering from

the program FOX[e] A large number of trial structures were calculated for each

compound using default parameters. No preferred orientation correction for all

compounds was applied. A total of six positional parameters (XYZ) for the Cu atom

and the S-ligand, and four orientation angles of the S-ligand were varied. All torsion

angles could be fixed. When the calculated ?2 reduced to a minimal level (5–10 times

of the original profile ?2 value), those structure solutions were examined and judged

based on educated chemical and physical knowledge as well as the graphical fit

between the calculated and experimental diffractographs. Occasionally the initial

positions of the heavy atoms Cu and S were readily located and these models were

progressively completed by adding the missing light atoms (C, H, O, N) to the models.

c) Structural refinement: Prior to any structural refinement, the chemically sensible

structural model was manually adjusted so as to remove those unrealistic close

non-bonded contacts by applying the appropriate sets of atom-to-atom distance

restraints (minimum non-bonded distances of 2.0 Å and 2.6 Å for H···H and H···C

respectively). For instance, when those bad contacts were disappeared then the

corresponding weighing factors of those distance restraints were reduced accordingly.

The model adjustment process was repeated many times until there are no overlapped

atoms or unrealistic bad contacts for non-bonded atoms. Subsequent Rietveld profile

refinement by the full matrix least squares was carried out by GSAS/EXPGUI suite

programs.[f,g] Scattering factors, corrected for real and imaginary anomalous dispersion

terms were taken form the internal library of GSAS. Overall scale factor and the

coefficients of the linear interpolation background function were refined. Profile shape

parameters (mixed Pseudo-Voigt function 3)[h,i] instrumental parameters (S/L) and

(H/L), sample displacement (shft) and sample transparency (trns), Gaussian peak

width (GW) and the Lorentzian peak broadening factor due to the micro-strain effect

of crystallites (LY) were sequentially refined. Absorption correction for the surface

roughness using Suortti function (See GSAS Manual) was applied. When the

refinement of all these non-structural parameters became converged with a negligible

(shift/esd)2 value, the model-biased profile refinement was switched in which the unit

cell parameters (a, b, c and ß), atomic coordinates, background coefficients, peak

profile parameters were refined together to give the final Rp, Rwp, Rexp and RB factors

(Table 1). Final refinement plots for 1–3 and 6 are shown in Figures S1–4.

[a] A. Boultif, D. Löuer, J. Appl. Crystallogr. 2004, 37, 724-731

[b] P. E. Werner, L. Eriksson, M. Westdahl, J. Appl. Crysallogr. 1985, 18,

367–370.

[c] G. S. Pawley, J. Appl. Crystallogr. 1981, 14, 357–361.

[d] W. I. F. David, K. Shankland, DASH, Program for Structure Solution from

Powder Diffraction Data, Cambridge Crystallographic Data Center, Cambridge

2001, (License agreement No: D/1023/2002).

[e] V. Favre-Nicolin, R. Cerný, J. Appl. Crystallogr. 2002, 35, 734–743. FOX, “free

objects for crystallography”: A modular approach to ab initio structure

determination from powder diffraction.

[f] A. C. Larson, R. B. Von Dreele “General Structure Analysis System (GSAS)”,

Los Alamos National Laboratory Report LAUR 86–748 2004.

[g] B. H. Toby, EXPGUI, A Graphical User Interface for GSAS, J. Appl.

Crystallogr. 2001, 34, 210–221.

[h] P. Thompson, D. E. Cox, J. B. Hastings, J. Appl. Crystallogr. 1987, 20, 79−83.

[i] L. W. Finger, D. E. Cox, A. P. Jephcoat, J. Appl. Crystallogr. 1994, 27, 892−900.

Figure S1. Graphical plot of the final Rietveld refinement cycle for 1 (red crossed

signs = observed data points, green line = calculated profile, vertical ticks =

Bragg peak positions). Difference plot (magenta) between the experimental

and calculated powder diffraction profile is shown at the bottom of each

plot.

Figure S2. Graphical plot of the final Rietveld refinement cycle for 2.



Figure S5. Powder XRD patterns of polycrystalline solids of 4, 5 and 7.

Figure S6. FT-IR spectrum of polycrystalline solid sample of 7 in a KBr pellet.

Figure S7. In-situ variable-temperature X-ray diffractographs of 1.

Figure S8. In-situ variable-temperature X-ray diffractographs of 7.

Figure S9. In-situ variable-temperature X-ray diffractographs of [Cu(SCH3)]8 .

Figure S10. TEM image (left) and SAED pattern (right) of nano-rods of 2.

Figure S11. TEM image (left) and SAED pattern (right) of nano-rods of

[Cu(SCH3)]8 .

Figure S12. TEM image (left) and SAED pattern (right) of nano-rod of 3.

Figure S13. TEM images (left) and SAED pattern (right) of the nano-rods of 4.

Figure S14. TEM image (left) and SAED pattern (right) of nano-rods of 5.

Figure S15. TEM image (left) and SAED pattern (right) of nano-crystals of 7.

Device Fabrication and Charge Mobility Measurement

A common substrate-gate structure field effect transistor (FET) was fabricated. Gate

oxide SiO2 layer (100 nm, relative permittivity = 3.9) was thermally grown on heavily

doped n-type Si substrate (gate electrode). An image reversal photolithography

technique was used to form an opening on the photoresist layer for the source and drain

patterns on the gate oxide. Source and drain metal layers, consisting of Ti adhesion

film (10 nm, lower) and Au conductive film (50 nm, upper), were deposited by thermal

evaporation. The channel length and width of the devices were 100 and 1000 µm

respectively. After metal film deposition, a standard lift-off process in acetone was

used to remove the metal film on top of the photoresist pattern, leaving behind the

Ti/Au source/drain contact patterns. Solids of 1–3 and [Cu(SCH3)]8 was added in

methanol and ultrasonicated for more than 12 hours to disperse the nano-rods in the

solution. Later the dispersed nano-rods were drop cast on the top of patterned bottom

contact FET device. In addition, we fabricated the devices using those solutions

without ultra-sonification. We found that considerable amount of highly-aggregated

nano-rods were present in these solutions that gave super-saturated current-voltage

behaviors with high channel currents and showed p-type behaviors. This is probably

because of bulk conduction between the source and drain electrodes due to these

enhanced aggregation of the nano-rods. The transistor output and transfer

characteristics were measured with a probe station under a nitrogen atmosphere using a

Keithley K4200 semiconductor parameter analyzer. Although a non-saturating

behavior was found for these nano-rod FET devices, a clear effect of the gate on the

current has been observed as shown in Figure 6. Since the saturation of the drain

current was not attained, the charge-carrier mobility was extracted from the linear

regime using ID,lin vs. VG relation.[a] At the linear regime where VDS <<VGS,

(where W is the channel width; L is the channel length; Ci is the capacitance of the SiO2

insulating layer; VGS is the gate voltage and Vt is the threshold voltage).

[a] S. M. Sze, Physics of Semiconductor Devices, Wiley, New York, 1981.

Conductivity measurements of pellet samples of 1 and Cu2O were performed by the

Model 6221 (Keithley Instruments, Inc.) with a four-point collinear probe (Keithley

Application Note Series No. 2615).

µ =∂Ids ∂Vgs L

WCoxVd

Optical Band Gaps Determinations using diffuse reflectance spectroscopy

y = 40.634x - 102.42

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

1

x-intercept = 2.52 eV

Figure S16. Plot of {hν ln[(Rmax - Rmin)/(R - Rmin)]}2 against hν for 1.

y = 20.216x - 52.328

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

2



y = 37.371x - 100.01

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

3



y = 136.67x - 358.64

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

4



y = 137.15x - 270.8

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

5



y = 190.55x - 425.6

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

6



y = 110.53x - 327.14

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

7



y = 75.27x - 200.93

0

2

4

6

8

10

12

14

16

18

20

1 1.5 2 2.5 3 3.5

Photon Energy (eV)

{hv

ln[(

Rm

ax -

Rm

in)/

(R -

Rm

in)]

}^2

(CuSMe)8


Figure S23. Plot of {hν ln[(Rmax - Rmin)/(R - Rmin)]}2 against hν for [Cu(SMe)]8 .

Documents

Supporting Information · Data collection parameters: 2? range = –60 º, step size = 0.02 °,3 scan speed = 10 second/step. Reproducible dataset of each sample was obtained and