A theoretical study on the insights of designing and optimization of a CsSn(IxBr1-x)3 based solar cell

This work focuses on designing and optimizing a lead-free perovskite solar cell. The significance of band gap grading in obtaining better performance of the solar cell was studied in detail with CsSn(I_xBr_1-x)₃ ($0\le x\le 1$) being used as the active absorber material. The device showed a maximum power conversion efficiency (PCE) of $\sim 32.32\%$ when the interfacial defects were not considered. The optimum thickness was obtained to be 1 μm, and the corresponding doping concentration was 10²⁰ cm⁻³. Further, a detailed discussion on the band diagrams, electric fields, and different recombination processes has been carried out in this work to get an idea about the varying PCE values at different operating conditions. The presence of Shockley-Read-Hall (SRH) recombination at various temperature values was observed, which partially contributed to the reduction in PCE values at higher temperatures. This work also discusses briefly about the probable losses involved with the device, which may be considered as the plausible reasons for obtaining PCE values less than the Shockley Quisser (SQ) limit. This information opens up a wide window for researchers to experimentally fabricate solar cells with proper cautions so that a device with PCE value exceeding SQ limit can be made available commercially.