Achieving High Photoluminescence Quantum Yield in Sb-Doped Indium-Based Hybrid Halides for Single-Component Warm White LEDs

Indium(III)-based hybrid halides are emerging low-dimensional luminescent materials; however, their rigid lattices and d 10 electronic configuration of In 3+ suppress intrinsic self-trapped-exciton (STE) emission, leading to limited photoluminescence quantum yield (PLQY). To address this issue, Sb 3+ is doped into the 0D (Me 2 NH 2 ) 4 InCl 7 host, transforming it from a nearly non-emissive material into a highly efficient warm-white STE emitter. The optimized (Me 2 NH 2 ) 4 InCl 7 :0.2Sb 3+ delivers a near-unity PLQY (∼100%) under 350 nm excitation. Single-crystal structural analysis and theoretical calculations reveal substitutional Sb 3+ at In 3+ sites, inducing locally distorted [SbCl 6 ] octahedra. This Sb 3+ -triggered local lattice distortion strengthens electron–phonon coupling, and it deepens the STE potential well and suppresses non-radiative relaxation pathways, thereby enabling robust broadband STE emission with a microsecond-scale lifetime (4.28 µs), a large Stokes shift (280 nm), and a wide bandwidth (177 nm). This work provides a facile route to realize warm-white emission from a single host lattice based on stable, low-toxicity indium-based hybrid halides.