The organic HTL in highly efficient germanium-alloyed CsSnI₃ perovskite solar cell: a modelling and computational analysis

It is usually anticipated that perovskites will be an appealing material for extremely effective solar cells. However, its practical applications are constrained by its hazardous properties and stability. Thus, CsSn_0.5Ge_0.5I₃, a more environmentally benign substitute for toxic lead-based perovskites, provides superior stability in solar cells. This work reports on the numerical modeling and computational analysis of a heterostructure CsSn_0.5Ge_0.5I₃, with TiO₂ and D-PBTTT-14 serving as the electron and hole transport layers, respectively. The introduction of D-PBTTT-14 as a hole transport layer was motivated by its superior stability over existing organic HTLs. Furthermore, the higher electron-hole pair generation rate and very favorable absorption coefficients of each layers manifested improved efficiency. Various parameters were examined to enhance the newly designed solar cell performance such as: thickness, defect density, doping density, coefficient of radiative recombination, defect at interface, shunt and series resistance, front and back contacts, and operating temperature. Perovskite solar cells with their current architecture have the potential to achieve a current density (J_sc) of 28.31 mA cm⁻², an open-circuit voltage (V_oc) of 1.24 V, a fill factor (FF) of 85.90%, and efficiency of 30.27%.