Perfluoroarene-Based Tin Halide Perovskite Photovoltaics

Hybrid halide perovskites are among the most promising candidates for next-generation photovoltaics. The most investigated perovskite solar cells are lead based, which poses environmental concerns, making finding sustainable alternatives a pressing issue. Tin-based halide perovskites are attracting interest as an alternative. However, their application in photovoltaics is hindered by the high concentration of defects and sensitivity to oxidation, compromising their performance and stability. Herein, perfluoroarene organic cations, namely 2-(perfluorophenyl)methylammonium (F-BNA) and 1,4-(perfluorophenyl)dimethylammonium (F-PDMA), are applied to form layered (2D) Ruddlesden–Popper and Dion–Jacobson tin-based perovskites, respectively. Following a detailed structural and optoelectronic characterization, the perfluoroarenes are applied to formamidinium (FA)-based FASnI3 perovskite solar cells and an effective solvent is identified for their processing, 2-pentanol. While F-PDMA forms a 2D/3D heterostructure, F-BNA remains assembled as a molecular interlayer, demonstrating higher photovoltaic performance with limited operational stability. This challenges the conventional role of mixed-dimensional heterostructures in tin perovskite photovoltaics and opens new perspectives for advanced material design and device engineering.