Enhancing the efficiency and stability of Cs2AgBiBr6 solar cells via MAPbBr3 decoration

Abstract

Eco-friendly perovskite materials like Cs₂AgBiBr₆ show promise for sustainable photovoltaics but suffer from efficiency limitations due to their wide bandgap (E_g) (1.94 eV). This study overcomes this challenge by incorporating 15 % MAPbBr₃ into Cs₂AgBiBr₆ via a sol-gel method. Structural analyses show that MAPbBr₃ integration induces compressive lattice strain, reduces dislocation density by 38 %, and increases crystallite size from 27 nm to 33 nm, enhancing crystallinity. Optical analysis reveal a narrowed bandgap (1.90 eV), higher dielectric constants, and refractive indices, improving light absorption and charge generation. Photovoltaic devices with MAPbBr₃-decorated Cs₂AgBiBr₆ achieve a 25 % efficiency (η) boost (5.05 % vs. 4.04 %) due to increased short-circuit current density (J_sc) (6.91 vs. 5.81 mA·cm⁻²) and suppressed recombination. Electrochemical impedance spectroscopy confirms improved charge transport, evidenced by a smaller Nyquist plot semicircle. This work demonstrates the potential of hybrid perovskite engineering to enhance solar cell performance while maintaining eco-friendliness.