Room temperature buried molecular engineering boosts the photovoltaic performance of wide-bandgap and all-perovskite tandems

Abstract

As a critical light-harvesting component in perovskite-integrated tandem photovoltaic architectures, wide-bandgap (WBG) perovskite absorbers have attracted considerable research interest. However, WBG perovskite solar cells (PSCs) often exhibit poor fill factor (FF) and substantial open-circuit voltage (V_OC) loss, primarily owing to pronounced non-radiative recombination, together with suboptimal charge transport dynamics. In this work, we inserted 4-guanidinobenzoic acid methanesulfonate (GBAM) into the interface between perovskites and hole transporting self-assembled monolayers. After being dried in a nitrogen atmosphere at room temperature, the GBAM film and the subsequently deposited perovskite film underwent an annealing process together to achieve buried interface improvement of the WBG perovskite. The results show that GBAM not only improves the band alignment of the perovskite interface and enhances the extraction of interface carriers, but also elevates the quality of the perovskite film and reduces interface losses. Eventually, 1.78 eV WBG and 1.53 eV normal PSCs based on GBAM achieved enhanced V_OC and FF, as well as a PCE of 20.9% and 26.16%, respectively. Furthermore, a two-terminal perovskite-perovskite tandem solar cell, formed by combining a narrow-bandgap tin–lead perovskite cell with a WBG perovskite cell, demonstrates an efficiency exceeding 29%. Our work provides a feasible approach for boosting the photovoltaic performance of WBG and all-perovskite tandems.