Cyclopentylethanamine Hydroiodide for Efficient and Stable 2D/3D Hybrid Perovskite Solar Cells

The utilization of organic amine salt treatment for the formation of 2D/3D heterojunctions has emerged as a highly effective strategy for achieving both efficient and stable halide perovskite solar cells. The creation of a 2D phase necessitates specific structural attributes within the amine molecules. While previous reports have predominantly focused on amine molecules containing linear alkyl chains, benzene rings, and heterocyclic rings to fulfill these requirements, the exploration of amine molecules incorporating cycloalkane moieties remains limited. In light of this, we introduce cyclopentanethylamine hydroiodate (CPEAI) as an innovative amine salt for the in situ growth of 2D passivation layers on 3D perovskite surfaces. Through the application of the 2D perovskite treatment, nonradiative recombination processes are effectively suppressed, leading to an extension of the carrier lifetime. This treatment also rationalizes the energy-level architecture. Consequently, devices treated with CPEAI exhibit an elevated open-circuit voltage and filling factor. Notably, the champion efficiency reaches 23.2%, surpassing the control device efficiency of 20.8%. Furthermore, we conducted a prolonged environmental stability assessment, subjecting the devices to 1000 h of exposure to air with approximately 40% relative humidity. Remarkably, the CPEAI-treated devices sustained an initial efficiency of 89.5%, whereas the control group maintained an efficiency of only 76.1%. This stark contrast underscores the substantial enhancement in environmental robustness facilitated by the CPEAI treatment. Our work unequivocally demonstrates the promising potential of cycloalkane-containing amine molecules in advancing the efficiency and stability of 2D/3D halide perovskite solar cells.