Metal Halide Regulated Photophysical Tuning of Zero-Dimensional Organic Metal Halide Hybrids: From Efficient Phosphorescence to Ultralong Afterglow

Abstract

The photophysical tuning is reported for a series of tetraphenylphosphonium (TPP) metal halide hybrids containing distinct metal halides, TPP2MXn(MXn=SbCl5, MnCl4, ZnCl4, ZnCl2Br2, ZnBr4), from efficient phosphorescence to ultralong afterglow. The afterglow properties of TPP(+)cations could be suspended for the hybrids containing low band gap emissive metal halide species, such as SbCl(5)(2-)and MnCl42-, but significantly enhanced for the hybrids containing wide band gap non-emissive ZnCl42-. Structural and photophysical studies reveal that the enhanced afterglow is attributed to stronger pi-pi stacking and intermolecular electronic coupling between TPP(+)cations in TPP(2)ZnCl(4)than in the pristine organic ionic compound TPPCl. Moreover, the afterglow in TPP(2)ZnX(4)can be tuned by controlling the halide composition, with the change from Cl to Br resulting in a shorter afterglow due to the heavy atom effect.