o-Phenylenediamine Doped Tin-Based Two-Dimensional Perovskite for Light-Emitting Device Applications

Two-dimensional (2D) Sn-based perovskites have emerged as a promising alternative to Pb-based perovskites due to their nontoxic nature. However, Sn2+ ions tend to get oxidized to Sn4+ during the synthesis process, leading to crystalline defects and rapid nonradiative transitions, which limits their applications. In this study, we present a facile molecular doping strategy for (C18H35NH3)2SnBr4 perovskite by introducing o-phenylenediamine (oPD) in the precursor solution. The oPD serves a dual role: it not only acts as an electron donor, creating a reducing environment to suppress the oxidation of Sn2+, but also functions as a chelating agent, forming stable compounds with Sn2+. This approach results in 20% oPD doped (C18H35NH3)2SnBr4 perovskite, which exhibits a high photoluminescence quantum yield (PLQY) of 95.3% and excellent stability against oxygen. Furthermore, UV-pumped orange and white light-emitting diodes (LEDs) with a CIE coordinate (0.562, 0.431, 0.327, and 0.346) were produced using oPD-doped 2D tin-based perovskite powders, respectively. These findings suggest that the doping strategy has great potential to enhance the stability of 2D Sn-based perovskites and facilitate their application in the field of lighting devices.