Low-dimensional organic–inorganic metal halides, which have exceptional host–guest structures and high radiative recombination have emerged as a primary focus in the exploration of multifaceted optoelectronic materials. Nevertheless, the employment feasibility of these materials in optoelectronic field is significantly hindered by the unavoidable thermal quenching effect. In this paper, zero-dimensional (0D) hybrid metal halide (Ph3S)2SbCl5 exhibited a negative thermal quenching effect (NTQ) between 90 K and 300 K, and the color of the powder gradually changed from pink (670 nm) to orange (645 nm). The origin of the negative thermal quenching effect in (Ph3S)2SbCl5 is attributed to trap states induced by structural defects, as supported by experimental characterization and first-principles calculations. The potential application of this material in light-emitting diodes (LEDs) is explored, showing good color rendering index (95.2) and thermal stability. By uncovering the impact of defects on the photophysical characteristics of materials, this research paves the way for exploring novel approaches to enhance the performance of LEDs based on NTQ mechanism.