Performance limiting factors of Cu2ZnSn(S Se1−)4 solar cells prepared by thermal evaporation

Abstract

Cu 2 ZnSn(S x Se 1-x) 4 (CZTSSe) thin film solar cells have been prepared by vacuum-based thermal evaporation of metal and binary sulfide precursors followed by annealing in a mixed chalcogen vapor at 550°C for one hour. The Zn/Sn ratio in the precursor was varied from 0.75-1.50 keeping the Cu/(Zn+Sn) ratio constant at 0.7. The best performing solar cell was obtained with a final film composition of Cu/(Zn+Sn) = 0.77 and Zn/Sn = 1.13 corresponding to a Zn/Sn ratio of 0.9 in the precursor. The champion cell exhibited an open-circuit voltage (V OC) of 506 mV, shortcircuit current density (J SC) of 22.92 mA/cm 2 , and a fill factor (FF) of 35% resulting in a total area efficiency (η) of 4.06% without any antireflection coating. Cell performance was found to be limited by high series resistance (R S) = 31.1 Ω and a low shunt resistance (R sh) = 125.2 Ω. No detrimental secondary phases, such as Cu 2-x S(Se) or ZnS were detected in the absorber film. Microstructural investigation suggested that small multigrain structure of the CZTSSe absorber layer, presence of an interfacial Mo(S,Se) y blocking barrier, and micro air-voids at the Mo back contact are the major contributors to the origin of high R s. Morphological study of the CZTSSe film surface by atomic force microscopy revealed micro-pores that act as low resistance shunt paths and explains the source of such low R sh. The performance limiting factors of the vacuum based thermally evaporated CZTSSe thin film solar cells are reported.

Design and Implementation of MATLAB-Simulink Based Solar Cell Modeling and PV System Design Exercises for Advanced Student Learning

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Optimizing the Ratio of Sn4+ and Sn2+ in Cu2ZnSn(S,Se)4 Precursor Solution via Air Environment for Highly Efficient Solar Cells

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Development of Low-cost Remote Online Laboratory for Photovoltaic Cell and Module Characterization

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