On–Off Switching of Singlet Self‐Trapped Exciton Emission Endows Antimony‐Doped Indium Halides with Excitation‐Wavelength‐Dependent Luminescence
Résumé
Excitation‐wavelength‐dependent (Ex‐De) emitters are a fascinating category of luminescent materials whose emission properties vary with the wavelength of the light used for excitation. Antimony (Sb3+)‐doped indium (In)‐based metal halides are efficient light emitters; however, the peak fluorescence emission of most Sb3+‐activated In‐halide remains independent of the excitation wavelength. Here, the study introduces a new Sb3+‐doped In‐halide cluster, (BDPA)2InCl5:Sb (BDPA+ = C15H18N+, benzyldimethylphenylammonium), which demonstrates efficient Ex‐De emission originating from the on–off switchable fluorescence behavior of singlet self‐trapped exciton (STE) in 5‐coordinate Sb3+ dopant. Interestingly, when excited within the range of 240–370 nm, photoluminescence (PL) spectra of (BDPA)2InCl5:Sb show both singlet and triplet STE emission. However, under excitation wavelengths of 370 to 420 nm, the singlet STE emission is absent, resulting in a noticeable correlated color temperature change from 1700 to 3800 K. The study provides a new approach to designing color‐tunable Sb3+‐based luminophores, and also presents a novel application scenario for the widely recognized Sb3+ doping strategy.