Electrical and impedance spectroscopy analysis of sol-gel derived spin coated Cu2ZnSnS4 solar cell

We carried out electrical and impedance studies on solution derived Al:ZnO/ZnO/CdS/Cu2ZnSnS4/ Mo/Glass multilayered solar cell structures to understand their impact on photovoltaic performance. The Cu2ZnSnS4 layer is synthesized on a molybdenum (Mo) coated soda lime glass substrate as an absorber and characterized intensively to optimize the absorber physical properties. The optimized Cu2ZnSnS4 is p-type with 5.8 x 10(17) cm(-3) hole carrier concentration. The depletion width of the junction is around 20.5 nm and the diffusion capacitance is similar to 35.5 nF for these devices. We observed relatively large minority carrier life time similar to 23 mu s for these structures using open voltage decay analysis. The measured Cu2ZnSnS4/MoS2 and Cu2ZnSnS4/CdS interface resistances are 7.6 k Omega and 12.5 k Omega, respectively. The spatial inhomogeneities are considered and the corresponding resistance is similar to 11.4 k Omega. The impedance measurements suggest that in conjunction with series resistance similar to 350 Omega, the interface and spatial inhomogeneity resistances also give a significant contribution to the photovoltaic performance. Published by AIP Publishing.