Self‐Trapped Exciton Emission with High Thermal Stability in Antimony‐Doped Hybrid Manganese Chloride

Abstract Self‐trapped exciton (STE) emission in some metal halides has acquired great interest in recent years due to their broadband emission, large Stokes shift, and high photoluminescence quantum yield (PLQY). However, severe thermal quenching of STE emission is still a critical bottleneck that impedes their application in light‐emitting field. Herein, a novel zero‐dimensional hybrid metal halide, Sb³⁺‐doped (BTPP)₂MnCl₄ (BTPP = Benzyltriphenylphosphonium), is accordingly synthesized to address this issue. This compound exhibits excitation‐dependent dual emissions including STE emission of antimony chloride tetrahedron and ⁴T₁‐⁶A₁ transition of Mn²⁺ ions, resulting in a tunable emission color from green to orange. More importantly, the PL intensity of STE emission at 420 K in (BTPP)₂MnCl₄:2.0%Sb can maintain 72.5% of its ambient value, which is superior to current organic–inorganic hybrid metal halides. Temperature‐dependent and time‐resolved spectroscopy results suggest that the high thermal stability of STE emission originates from the efficient energy transfer from (BTPP)₂MnCl₄ host to antimony chloride tetrahedron, which promotes the formation of STEs. The white light‐emitting diode based on this (BTPP)₂MnCl₄:2.0%Sb phosphor exhibits high‐performance warm white light with a correlated color temperature of 4827 K and a color rendering index of 88.7, which demonstrates its potential in solid‐state lighting applications.