Methanol-induced luminescence vapochromism based on a Sb3+-doped organic indium halide hybrid

Abstract

Ion doping has been demonstrated as a practical approach to achieving highly efficient luminescence in both inorganic phosphors and organic-inorganic hybrids. The as-formed doping species show great potential in optoelectronic applications due to their high photoluminescence quantum yield (PLQY) and excellent stability. Herein, we report highly emissive Sb3+-doped indium halides (C6H18N2)InCl5·H2O:Sb (C6H18N22+ = N,N,N′,N′-tetramethylethane-1,2-diammonium) prepared by solution evaporation methods with an emission that peaked at 565 nm and a PLQY of 74.6%. Photophysical characterizations and density functional theory computational studies verify the broadband emission originating from a self-trapped exciton. Interestingly, a drastic red shift of the emission peak from 565 to 663 nm with yellow luminescence turning to red is observed once the (C6H18N2)InCl5·H2O:Sb hybrid is exposed to methanol vapor. Moreover, when the methanol-exposed hybrid is put in air, the emission reverts to 565 nm in several minutes. Single-crystal X-ray diffraction studies show a subsequent structure distortion upon the coordination of methanol to the Sb(III) center, which is responsible for the drastic red shift of the emission. Encouragingly, we found that (C6H18N2)InCl5·H2O:Sb exhibits a specific response to methanol vapor after screening a series of volatile organic compounds with different polarities. Besides, a negligible change of the emission intensity is observed after several cycles of uptaking and releasing methanol. The high fatigue resistance and specific solvent response of the Sb3+-doped indium halide make it a very promising methanol detector.