High-efficiency histamine-In-based halide phosphors with excellent thermal stability

Abstract

<p indent=0mm>Metal halide perovskite semiconductors with attractive optoelectronic properties have potential applications in solar cells, light-emitting diodes (LEDs) and lasers. However, the toxicity and instability of Pb-based perovskites make them difficult to maintain long-term and uniform device performances in different environments (such as high temperature and humidity), hindering their further large-scale fabrication. These problems can be avoided by a reasonable design of novel low-dimensional lead-free metal halides (LLMHs). LLMHs with a low-dimensional structure provide a promising platform to achieve efficient broadband emission, especially considering their large exciton binding energy and strong electron-phonon coupling. In our recent studies, we have achieved efficient broadband emission in layered Na–In halide perovskites, demonstrating the feasibility of the Sb doping strategy. However, their thermal stability remains unsatisfactory, because their photoluminescence (PL) intensity decreases by 17.1%–43.5% after the heating-cooling cycle. For LLMHs, it is still a challenge to obtain broadband emission that combines high photoluminescence quantum efficiency (PLQE) and thermal stability. Hence, utilizing the Sb³⁺ doped LLMHs of (HA)₂KInCl₈–Sb (2D) and (HA)₂InCl₇·H₂O–Sb (0D) (HA²⁺=histamine) with PLQE of 58.8% and 63.4%, respectively. The van der Waals forces and hydrogen bonding of organic components can be enhanced by using HA²⁺ as A-site organic cations. By monitoring the fluorescence intensity during the heating-cooling cycles, we evaluated the thermal stability of two materials. They have excellent thermal stability and can maintain more than 95% PL intensity (relative to initial intensity) after the heating-cooling cycles, demonstrating the feasibility of this strategy.