Direct correlation between open-circuit voltage and quasi-fermi level splitting in perovskite solar cells: a computational step involving thickness, doping, lifetime, and temperature variations for green solutions

In this study, a 1D perovskite-based solar cell was simulated using COMSOL, incorporating CH₃NH₃GeI₃ (organic in-organic hybrid) as an absorber layer, SnO₂ as the electron transport layer (ETL), and Cu₂Te as the hole transport layer (HTL). The simulations reveal that reducing the ETL's thickness enhances current density (<i>J</i>), although the maximum output power (<i>P</i> _max) diminishes with ETL's thickness. Conversely, increasing the absorber layer's thickness boosts open-circuit voltage (<i>V</i> _oc) and efficiency, exhibiting direct relation between <i>V</i> _oc and quasi-Fermi level splitting. Furthermore, variations in HTL thickness do not significantly affect <i>V</i> _oc or <i>P</i> _max. Notably, <i>V</i> _oc and <i>P</i> _max both increase with acceptor density, conversely, increase in donor density leads to declines in both <i>V</i> _oc and <i>P</i> _max. While extending the electron-hole (e-h) lifetime within the ETL results in marginal efficiency improvements, significant enhancements in the e-h lifetime within the absorber layer substantially improve performance. However, the efficiency remains unaffected by variations in the e-h lifetime of the HTL. Additionally, higher operating temperatures adversely impact device performance, reducing <i>J</i>, <i>V</i> _oc, <i>P</i> _max, fill factor, and overall efficiency. This study provides critical insights into optimizing material properties and device parameters for experimental applications, underscoring the potential of CH₃NH₃GeI₃-based perovskites as viable candidates for next-generation photovoltaic technologies.