Universality of non-Ohmic shunt leakage in thin-film solar cells

Author

• Sourabh Dongaonkar, Purdue University - Main CampusFollow
• Jonathan D. Servaites, Northwestern University
• Grayson M. Ford, Purdue University - Main Campus
• Stephen Loser, Northwestern University
• James E. Moore, Purdue University - Main Campus
• Ryan M. Gelfand, Northwestern University
• Hooman Mohseni, Northwestern University
• Hugh W. Hillhouse, Purdue University - Main Campus
• Rakesh Agrawal, PurdueFollow
• Mark A. Ratner, Northwestern University
• Tobin J. Marks, Northwestern University
• Mark Lundstrom, Purdue University
• Muhammad A. Alam, Purdue University - Main CampusFollow

Abstract

We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) cells, and Cu(In,Ga)Se₂ (CIGS) cells. All three device types exhibit a significant shunt leakage current at low forward bias (V< ∼ 0.4) and reverse bias, which cannot be explained by the classical solar cell diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to the traditional constant shunt resistance model for photovoltaics. We show here that this shunt leakage (I_sh), across all three solar cell types considered, is characterized by the following common phenomenological features: (a) voltage symmetry about V = 0, (b) nonlinear (power law) voltage dependence, and (c) extremely weak temperature dependence. Based on this analysis, we provide a simple method of subtracting this shunt current component from the measured data and discuss its implications on dark IV parameter extraction. We propose a space charge limited (SCL) current model for capturing all these features of the shunt leakage in a consistent framework and discuss possible physical origin of the parasitic paths responsible for this shunt current mechanism.

Comments

Copyright (2010) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics 108, 124509 (2010) and may be found at http://dx.doi.org/10.1063/1.3518509. The following article has been submitted to/accepted by Journal of Applied Physics. Copyright (2010) S. Dongaonkar, J. D. Servaites, G. M. Ford, S. Loser, J. Moore, R. M. Gelfand, H. Mohseni, H. W. Hillhouse, R. Agrawal, M. A. Ratner, T. J. Marks, M. S. Lundstrom, and M. A. Alam. This article is distributed under a Creative Commons Attribution 3.0 Unported License.

Keywords

solar cells, photovoltaics, shunt, thin films, space charge limited, amorphous silicon, CIGS, organic BHJ

DOI

10.1063/1.3518509

Citation

Journal of Applied Physics 108, 124509 (2010)

Date of this Version

12-2010

Recommended Citation

Dongaonkar, Sourabh; Servaites, Jonathan D.; Ford, Grayson M.; Loser, Stephen; Moore, James E.; Gelfand, Ryan M.; Mohseni, Hooman; Hillhouse, Hugh W.; Agrawal, Rakesh; Ratner, Mark A.; Marks, Tobin J.; Lundstrom, Mark; and Alam, Muhammad A., "Universality of non-Ohmic shunt leakage in thin-film solar cells" (2010). Birck and NCN Publications. Paper 739.
http://dx.doi.org/10.1063/1.3518509