Enhancing solar cell efficiency: lead-free double perovskite solar cells Cs2AgBiBr6 with magnesium-doped and Zn2SnO4 electron transport layer

The lead-free halide double perovskite solar cell (LFHDPs) Cs2AgBiBr6 has emerged as a compelling alternative to conventional lead-based perovskites (LBPs) owing to its notable advantages in chemical stability and non-toxicity. However, due to their large indirect bandgap (E-g), Cs2AgBiBr6 solar cells exhibit low efficiency (eta). To address these challenges, this study explores the doping of Cs2AgBiBr6 double perovskite with Magnesium (Mg), resulting in a reduced E-g and improved eta. Mg doping not only mitigates recombination losses but also enhances charge carrier mobility and stability. Additionally, the incorporation of a Zn2SnO4 (ZTO) electron transport layer (ETL) enhances eta and stability by facilitating rapid charge injection and electron diffusion. Excellent optical and electrical characteristics of the ZTO-based ETL make it suitable for improving the eta of charge collection and light harvesting in solar cells. Importantly, the Cs2Ag0.95Mg0.05BiBr6 solar cell exhibits enhanced performance, significantly, the fabricated solar cells exhibit improved performance. The measured values include an open circuit voltage (V-oc) of 0.9 V, a short circuit current density (J(sc)) of 5.77 mA-cm(-2), a fill factor of 0.76, and a eta of 3.98%. This study not only helps to overcome film formation issues but also validates stable Cs2Ag0.95Mg0.05BiBr6 as an efficient material for solar applications. Overall, our study improves solar technologies that are friendly to the environment.