Comprehensive TCAD simulation and optimization of lead-free AgBiI4 solar cells: Migration from single cell to high-performance indoor photovoltaic modules

Abstract

The growing demand for sustainable power sources for IoT devices highlights the need for eco-friendly, efficient, and lead-free indoor photovoltaic (IPV) technologies, as current lead-based perovskites pose environmental and health risks. This study presents a comprehensive TCAD simulation of lead-free AgBiI₄ (ABI) perovskite-based photovoltaic cells and modules optimized for indoor energy harvesting. The simulation model was initially validated through calibration against an experimental AgBiI₄-based solar cell, featuring the structure ITO/SnO₂/AgBiI₄/PTAA/Au. Loss analysis of the calibrated cell revealed that the cell suffers from different issues, including high defects and low absorption capabilities. To address these issues, we investigated some potential routes for performance enhancement through critical parameter optimizations such as absorber thickness, carrier lifetime, and band alignment. These improvements led to a significantly enhanced ABI-based cell design under white LED illumination. Furthermore, the study extended to the design of an ABI-based mini-module, analyzing the effects of gap width, geometric fill factor (GFF), and ITO sheet resistance on module efficiency. Module efficiencies of 5.15 % and 23.58 % under 2700 K LED illumination (1000 lx) were achieved for initial and optimized designs, respectively, with a total gap width of 0.9 mm in a four-cell series configuration. This research introduces a novel approach to optimizing ABI perovskite materials for IPVs, addressing the critical need for eco-friendly and lead-free alternatives to traditional lead-based perovskite technologies. By demonstrating significant improvements in efficiency and applicability, this study establishes ABI-based solar modules as promising candidates for powering indoor IoT devices.