Numerical optimization of cesium tin-germanium triiodide/antimony selenide perovskite solar cell with fullerene nanolayer

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 (J_SC) = 26.18 mA/cm², open circuit voltage (V_OC) = 0.37 V, and power conversion efficiency (PCE) = 5.19 %, while simulated parameters were FF of 54.68 %, J_SC of 27.54 mA/cm², V_OC of 0.36 V, and PCE = 5.55 %. The advancements 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/CsSn_0.5Ge_0.5I₃/Sb₂Se₃/CuInSe₂/Au structure was simulated, and significant results were achieved. Results showed that inserting the CsSn_0.5Ge_0.5I₃ layer led to an increase in PCE up to 11.42 %.