Photoluminescence of Singlet/Triplet Self-Trapped Excitons in Sb3+-Based Metal Halides

Emerging lead-free metal halides with low toxicity and unparalleled optoelectronic properties have attracted growing research interests, also demonstrating extensive application potentials. Among these, Sb3+-based all-inorganic/organic-inorganic hybrid metal halides become a vital group due to the special energy level distribution along with diverse optical properties. However, there remains a gap in understanding the relationship between the crystal structure and the radiation process of involved Sb3+ emission. Herein, the existing reports about Sb3+-based luminescent metal halides are revisited and their structure-luminescence-application relationship is explored, and it is further established that the triplet self-trapped excitons (STEs) emission of Sb3+ varies in different crystallographic environments and endows tunable luminescent performance. This work aims to provide constructive strategies in the further exploitation of Sb3+-based metal halides, and also guides the structural design and photoluminescence tuning of doped metal halide materials.