Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells Xin Yu, Craig Shaffer, Sanjay Behura, and Vikas Berry University of Illinois at Chicago, Illinois 60607, United States Photovoltaic and Spectral Responses Acknowledgements: University of Illinois at Chicago Solar device fabrications were made via standard photolithography and metallization processes Graphene Characterizations 600 700 800 900 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Quantum Efficiency (%) Wavelength (nm) Motivations Results and Discussions Experimental Approach Conclusion and Future Directions References • Energy from sunlight strikes the earth in 1 h (4.3x10 20 J) is more than all of the energy currently consumed on the planet in 1 year (4.1x10 20 J). Yet, only <0.25% of total electricity is generated from solar (2013). • Solar energy in wavelength from 600 to 1400 nm doesn’t get absorbed fully by the standard Si P-N junction solar cells. • Graphene/Si solar cells hold promise due to graphene’s broadband absorption, and high carrier mobility. Chemical Vapor Deposition setup • Scanning Raman spectroscopy with 532 nm laser excitation was employed to evaluate the directly grown graphene: thickness, defects, continuity, and uniformity. • From the Raman spectrum and mapping, it is confirmed that the few-layer graphene is continuously grown on n-Si surfaces. • Field Emission Scanning Electron Microscope (FESEM) was also used to characterize the graphene surface with and without Ag nanoparticles. D • Transfer-free graphene/Si solar cells developed via CVD. • PCE of 1.3% is achieved with Ag nanoparticles plasmonics. • EQE measurements also support the expected device performance. • H. A. Atwater and A. Polman, “Plasmonics for improved photovoltaic devices,” Nature Materials, 9: 205-214, 2010. • A. K. Geim and K. S. Novoselov, “The rise of graphene,” Nature Materials, 6: 183-191, 2007. • S. Behura et al., “Junction characteristics of chemically-derived graphene-p Si heterojunction solar cell,” Carbon, 67: 766-774, 2014. Graphene/SiNW Heterojunction Solar Cells Parameter w/o Ag NPs with Ag NPs Area (cm 2 ) 0.05 0.05 J sc (mA/cm 2 ) 14.77425 32.45456 V oc (V) 0.219231 0.182353 P in 0.005 0.005 Fill Factor 23.39% 21.89% Efficiency 0.76% 1.30% Graphene with NPs Graphene w/o NPs Source: Key World Energy Statistics 2015 H. A. Atwater, A. Polman, Nat. Mater. (2010) Schematic of graphene/n-Si solar cell J-V characteristics Cell performances EQE characteristics

Poster_CERS 2016_Direct Graphene-Si Solar Cells_Xin Yu

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Page 1: Poster_CERS 2016_Direct Graphene-Si Solar Cells_Xin Yu

Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar CellsXin Yu, Craig Shaffer, Sanjay Behura, and Vikas Berry

University of Illinois at Chicago, Illinois 60607, United States

Photovoltaic and Spectral Responses

Acknowledgements: University of Illinois at Chicago

Solar device fabrications were made via standard photolithography and metallization processes

Graphene Characterizations

600 700 800 9001.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

tum

Eff

icie

y (

Wavelength (nm)

Motivations

Results and Discussions

Experimental Approach

Conclusion and Future Directions References

• Energy from sunlight strikes the earth in 1 h (4.3x1020 J) is morethan all of the energy currently consumed on the planet in 1 year(4.1x1020 J). Yet, only <0.25% of total electricity is generated fromsolar (2013).

• Solar energy in wavelength from 600 to 1400 nm doesn’t getabsorbed fully by the standard Si P-N junction solar cells.

• Graphene/Si solar cells hold promise due to graphene’sbroadband absorption, and high carrier mobility.

Chemical Vapor Deposition setup

• Scanning Raman spectroscopywith 532 nm laser excitationwas employed to evaluate thedirectly grown graphene:thickness, defects, continuity,and uniformity.

• From the Raman spectrum andmapping, it is confirmed thatthe few-layer graphene iscontinuously grown on n-Sisurfaces.

• Field Emission ScanningElectron Microscope (FESEM)was also used to characterizethe graphene surface with andwithout Ag nanoparticles.

• Transfer-free graphene/Si solar cells developed via CVD.

• PCE of 1.3% is achieved with Ag nanoparticles plasmonics.

• EQE measurements also support the expected device performance.

• H. A. Atwater and A. Polman, “Plasmonics for improved photovoltaic

devices,” Nature Materials, 9: 205-214, 2010.

• A. K. Geim and K. S. Novoselov, “The rise of graphene,” Nature Materials,

6: 183-191, 2007.

• S. Behura et al., “Junction characteristics of chemically-derived graphene-p

Si heterojunction solar cell,” Carbon, 67: 766-774, 2014.Graphene/SiNW Heterojunction Solar Cells

Parameter w/o Ag NPs with Ag NPs