Tweaking the performance of thin film CIGS solar cell using InP as buffer layer

Abstract

In this paper, a high performing copper indium gallium selenide (CIGS) (CuIn1−xGaxSe2) based solar cell is designed using less toxic indium phosphide (InP) as a buffer layer. Conventional CIGS solar cell uses toxic cadmium sulfide (CdS) material as a buffer layer. Here InP is used in place of CdS, which is not only environmentally friendly but also gives better performance in terms of power conversion efficiency (PCE). In this work, proposed device structure comprises of following layers: glass substrate/n-ZnO (window layer)/n-InP (ETL)/p-CIGS (absorber)/p-MoS2 (HTL)/metal back contact. Device optimization is done by varying thickness, defect density, and doping concentration of absorber and buffer layers. Various electrical parameters like open circuit voltage (Voc), short circuit current density (Jsc), fill factor (F.F.), quantum efficiency (Q.E.), and PCE are obtained to study the behavior of the device. The performance of the proposed solar cell is also investigated by varying series-shunt resistance, temperature, and work function of front and back contact electrodes. The proposed structure shows maximum efficiency of 28.01% (Voc=0.8294 V, Jsc=39.26 mA/cm−2, FF=86.01%) at room temperature (300 K). All the analyses are done with the help of the SCAPS-1D simulation program.