Significance of the direct relation between the fill factor and hole transport layer thickness in perovskite-based solar cells for green energies

In response to the growing global energy crisis and environmental degradation, the development of clean, sustainable energy technologies is imperative. Solar energy, with its vast availability and minimal ecological footprint, is a leading candidate. Among the emerging photovoltaic technologies, perovskite solar cells (PSCs) are gaining attention for their tuneable optoelectronic properties and low-cost processing. This study employs a 2D model simulation on COMSOL Multiphysics to investigate two lead-free PSC designs, focusing on structural optimization. Notable results for the ZnSe/BiFeO₃/spiro-OMeTAD cell include a maximum short-circuit current density (<i>J</i> _sc) of 9.83 mA cm^-2 and a peak efficiency of 10.72% at 75 nm electron transport layer thickness, open-circuit voltage (<i>V</i> _oc) of 2.2 V at 125 nm hole transport layer thickness, and fill factor (FF) of 73.77% at 100 nm BFO thickness. For the ZnSe/CsSnI₃/spiro cell, a maximum efficiency of 17.56%, FF of 79.91%, <i>V</i> _oc of 1.01 V, and <i>J</i> _sc of 28.32 mA cm^-2 were achieved. The study specifically explored the direct relation between the FF and hole transport layer thickness in a perovskite-based green photovoltaic device. These findings highlight the promising potential of lead-free perovskites for efficient, stable, and environmentally benign solar cells. This work supports the advancement of inorganic PSCs, contributing to the global shift toward renewable energy.