The lead-free perovskite solar cells with the green synthesized BiI3 and AgI nanoparticles using Vitex agnus-castus plant extract for HTM-free and carbon-based solar cells

Abstract

A green BiI3 and AgI nanoparticles were synthesized using Vitex agnus-castus and then these nanoparticles were applied to obtain a high-quality methylammonium bismuth iodide ((CH3NH3I)3Bi2I9 = MBI) and AgBi2I7 as perovskite film. BiI3, MBI, and AgBi2I7 nanoperovskites have been proposed as viable candidates for concurrently resolving the instability and lead toxicity difficulties of unprecedented organic-inorganic hybrid halide perovskites. When the contact area between BiI3 and MBI and also AgI and BiI3 were increased due to the nanostructure of BiI3 and AgI, the reaction rate between BiI3 and methylammonium iodide (MAI) and also AgI and BiI3 was enhanced. Therefore, uniform and high crystalline perovskites layers without BiI3 residue was prepared. In this study, the vital role of the nanostructure perovskite layer in the stability and performance of the device is discussed.This resulted in a significant increase in power conversion efficiency (PCE), which reached 1.42%, as well as stability up to 7 days of AgBi2I7 solar cells against humidity, heat and light. Furthermore, without encapsulation, these devices exhibit superior tolerance under air conditions and high temperatures, providing new opportunities to promote the future development of lead-free AgBi2I7 nanoperovskites in the photoelectric field.