SCAPS-1D platform was used to simulate a solar cell with FTO/CdS/Sb2Se3/CuInSe2/Au structure which was recently fabricated by Liu et al. (2022) [1] [Journal of Energy Chemistry 68 521–528 (2022)] and a very similar result was obtained. Reported parameters were Fill Factor (FF) = 53.60 %, short circuit current density (JSC) = 26.18 mA/cm2, open circuit voltage (VOC) = 0.37 V, and power conversion efficiency (PCE) = 5.19 %, while simulated parameters were FF of 54.68 %, JSC of 27.54 mA/cm2, VOC of 0.36 V, and PCE = 5.55 %. The ad- vancements have been evaluated by analyzing FTO/CdS/Sb2Se3/CuInSe2/Au and FTO/C60/Sb2Se3/CuInSe2/Au configurations, serving as the reference cells. To improve the cell performance, the CdS layer was replaced with another layer (C60) which shows excellent electron transport properties. Replacing the CdS layer with C60 led to an increase in the power conversion efficiency by 65 % (from 5.55 % up to 9.20 %). In photovoltaic systems, the PCE constitutes a pivotal parameter that can be enhanced through the absorption of a broad spectrum of incident photons. Consequently, the implementation of two absorber layers within a solar cell, each characterized by a graded band gap energy, enables the capture of solar photons over a more extensive spectral range. Therefore, a perovskite containing a band gap of 1.5 eV, lead-free, and Sn-based was used as the second absorber layer in the device. Therefore, a solar cell with FTO/C60/CsSn0.5Ge0.5I3/Sb2Se3/CuInSe2/Au structure was simulated, and significant results were achieved. Results showed that inserting the CsSn0.5Ge0.5I3 layer led to an increase in PCE up to 11.42 %.
