Computational study of KGeCl₃ perovskite solar cells toward high efficiency via electron transport innovation

Germanium-based perovskite solar cells (PSCs) have gained attention as a promising alternative to conventional lead-based PSCs due to their environmentally friendly and non-toxic nature. However, their efficiency remains below optimal levels, requiring further exploration to enhance their performance. This study investigates a novel n-i-p structured germanium-based perovskite solar cell using the wxAMPS simulation. The baseline structure-FTO/TiO₂/KGeCl₃/Spiro-OMeTAD/Au-achieved a power conversion efficiency (PCE) of 18.55%. To improve efficiency, various electron transport layer (ETL) materials were evaluated, including TiO₂, IGZO, SnO₂, ZnO, ZnSe₂, WO₃, PCBM, and WS₂ TMDC. The results revealed that the WS₂ emerging as the most suitable candidate. Optimization of key parameters, including the thicknesses of WS₂ ETL (50 nm), Spiro-OMeTAD HTL (30 nm), and the absorber layer KGeCl₃ (600 nm), significantly improved device performance. Additional investigations into defect density, acceptor concentration, electron affinity, and donor concentration further optimized the device's operation. The study also analyzed the adverse effects of functional temperature, providing insights into stability and efficiency under real-world conditions. The optimized solar cell device demonstrated enhanced performance metrics: V_oc = 1.02 V, J_sc = 25.77 mA/cm², FF = 78.25%, and PCE = 22.98%. These findings highlight the potential of germanium-based perovskite solar cells as a sustainable, lead-free photovoltaic solution. The integration of WS₂ as an ETL paves the way for achieving high-efficiency, environmentally friendly solar cells, with promising implications for advancements in renewable energy solutions.