Alleviation of π–π* Transition Enabling Enhanced Luminescence in Emerging TpyInCl _x ( x = 3, 5) Perovskite Single Crystals

Abstract Organic–inorganic hybrid metal halide perovskites have played an important role in optoelectronic and photonic community owing to their remarkably high photoluminescence quantum yields and color tunability with ultrafast emission performance. Herein, two kinds of novel perovskite single crystals, i.e., TpyInCl ₃ and TpyInCl ₅ , grown by means of a solution‐processed hydrothermal method are innovatively designed. Regulating the polarity of the precursor solution allows to fine‐tune the light emission from pink to blue with an extremely short photoluminescence lifetime of 2.5 ns. The density functional theory calculations reveal that the unique luminescence characteristics are associated with the contribution of the terpyridine π–π* transition and the exciton quenching in the inorganic framework, that is, InCl ₃ /[In ₂ Cl ₁₀ ] ⁴⁻ , wherein the reduction of the recombination path and the increase of exciton quenching can effectively increase the luminous intensity. The current study provides a new paradigm toward designing multifunctional perovskite materials with tunable structure and electron dimension in emitter devices.