Performance optimization of lead-free potassium germanium halide based perovskite solar cells: A numerical study

Abstract

Conventional lead-halide perovskite solar cells (PSCs) have great potential as top contenders for commercial utilization due to their impressive performance. Nevertheless, the stability issues and undue toxicity have limited their widespread use. Consequently, lead-free germanium-based PSCs have materialized as potential substitutes due to their high working efficiency and exceptional sustainability. The current study has examined various configurations of non-toxic inorganic potassium germanium trichloride (KGeCl₃) based PSC structure by using different Hole Transport Layers (HTL) and Electron Transport Layers (ETLs) respectively. This work proposes an efficient Ge-based PSC (structure; FTO/MoO₃/KGeCl₃/WS₂/Au), which has been optimized theoretically using SCAPS-1D. The influence of the material parameters, such as the thickness of the absorber layer (nm), donor density (N_d), acceptor density (N_a), absorber defect density(N_t), interface layer defect density (IL1& IL2), series resistance (R_s) and shunt resistance (R_sh), and working temperature (K), has been optimized. The open circuit voltage (V_oc), current density (J_sc), fill factor (FF), and power conversion efficiency (PCE) of KGeCl₃-based PSC have all been commendably optimized. The results indicated WS₂ as the most effective ETL for KGeCl₃ with MoO₃ as an HTL, yielding notable cell performance with V_oc of 0.88 V, J_sc of 41.45 mA/cm², FF of 81.76 %, and PCE of 29.83 %. The outcomes of this simulation study suggest the utilization of KGeCl₃ as the absorber layer, in conjunction with WS₂ and MoO₃ as advanced ETL and HTL layers, which pays the way for continued development and optimization of Ge-based PSCs for potential applications.