Improving Efficiency and Stability of Perovskite Solar Cells by Modifying Mesoporous TiO2–Perovskite Interfaces with Both Aminocaproic and Caproic acids

Abstract

AbstractIn the field of photovoltaic industry, organolead halide perovskite solar cells (PSCs) as cleaner and cheaper photo‐voltaic devices have shown a bright prospect with power conversion efficiency (PCE) rapidly climbing from 3.8% to certified 22.1% in a few years. Interface engineering has been proven to be highly effective to solve the instability‐to‐moisture issue and enhance the performance of PSCs. Here, this work develops a simple and easy‐proceeding strategy that depositing both aminocaproic acid [H2NCH2(CH2)4COOH, abbreviated as AmCA] and caproic acid [CH3(CH2)4COOH, CA] at the mesoporous TiO2/perovskite interface leads to significant enhancement in both the efficiency and stability of PSCs. These two organic modifiers work synergistically to enhance the overall performance of PSCs by promoting electron transfer through the interaction between amino groups on AmCA and perovskite layer, and resisting moisture with alkyl chains from CA. The champion efficiency of modified cells reaches 18.2%, with an average PCE of 17.5% in reliable reproducibility, with significant improvement in stability under 50 ± 5% relative humidity in air. The developed simple interfacial modification approach should be effective to enhance both efficiency and stability of PSCs with other architectures as well. More importantly, this scenario may provide insight into the commercialization of perovskite solar cells in the not‐too‐distant future.