Photoluminescence and Stability of Dion–Jacobson Tin-Based Halide Perovskites with Different Spacer Cation Chain Length

Two-dimensional tin halide perovskites are of significant interest for light emitting applications. Here, we investigate the effect of organic cation A on the stability of different Dion–Jacobson tin-based halide perovskites. The ASnBr4 materials using diammonium cation A with shorter alkyl chains are found to exhibit improved stability, exhibiting dramatic stability difference between the most stable HDASnBr4, where HDA denotes 1,6-hexanediammonium, and two materials with 8- and 10-carbon alkyl chain ammonium cations. The HDASnBr4 powders were thermally stable at 100 °C in an argon environment but exhibited decreasing photoluminescence with time in ambient air at 100 °C. The sample degradation at 100 °C is accelerated compared to room temperature, but it proceeds along similar pathways, namely phase transformation followed by perovskite decomposition. Light emission from HDASnBr4 thin films could be further enhanced by methanol vapor treatment, and warm white emission with Commission Internationale de l’Eclairage (CIE) coordinates (0.37, 0.34) could be obtained by combining HDASnBr4 with a blue-emitting polymer film, while direct mixing of blue phosphor and HDASnBr4 powder yields white emission with CIE coordinates of (0.34, 0.32).