Halogen Difference Regulated Thermal Quenching Resistance of Mn-Based Hybrid Halides and Fluorescent Temperature Sensing Application

Abstract Organic−inorganic hybrid metal halide materials with resistance to thermal quenching have broad applications in areas such as solid-state lighting, display technology, optical sensing, and bio-imaging and have become one of the research hotspots in this field in recent years. In this work, based on a halogen engineering strategy, we successfully developed a Mn-based hybrid metal halide that simultaneously exhibits high photoluminescence (PL) quantum efficiency and excellent thermal quenching resistance. Based on the halogen engineering strategy, we synthesized two hybrid metal halides with anti-thermal quenching properties, namely, (C15H18N)2MnX4 (X = Cl, Br). Both compounds exhibit bright broadband green emission and demonstrate anti-thermal quenching behavior over a temperature range of 10−400 K. When Cl was replaced by Br, the resulting (C15H18N)2MnBr4 exhibited the best overall performance, with a photoluminescence quantum yield (PLQY) as high as 92.4% and only a 7.5% decrease in emission intensity over the 10−300 K range. The weak interactions between the organic cations and the metal halide polyhedra are the key source of this excellent performance. Compared with (C15H18N)2MnCl4, the weak interactions between the organic cations and the [MnBr4]2 polyhedra within the (C15H18N)2MnBr4 crystals are more abundant. These weak interactions restrict local structural distortion during heating and suppress non-radiative transitions, thereby stabilizing the internal energy transfer. On this basis, Sb3+ doping was introduced into (C15H18N)2MnBr4 to construct a dual-emission temperature-sensing system with high sensitivity. This work offers a feasible strategy for exploring advanced thermostable luminescent materials for high-performance fluorescent thermometry.