Unveiling Clusterization-Triggered Emission Mechanism Through a Small-Molecule Clusteroluminogen with Color Tunable and White-Light Emission

Clusterization-triggered emission (CTE) is a photophysical phenomenon where clusteroluminogens (CLgens) generate efficient luminescence through supramolecular self-assembly in the solid state. This phenomenon offers unique photophysical properties, distinguishing it from traditional chromophores. In the context of light-emitting devices, there is growing interest in single-component white-light (SCWL) emission, where a single material produces broad emission. However, SCWL emission based on CLgens has been rarely reported, particularly in single crystals, and fabricating SCWL emitters from small-molecule, nonconjugated luminogens remains a significant challenge. The underlying mechanism of CTE is still not fully understood, prompting investigations into small-molecule CLgens to explore their structure–property relationships. In this study, a novel organic salt, TET.Br4 (TET = N,N′-bis(2-aminoethyl)-1,3-propanediamine), is synthesized, consisting of saturated TET cations connected by a hydrogen-bonded network of bromine anions in the crystalline state. The photophysical properties of TET.Br4 are characterized through optical absorption, photoluminescence measurements, and density functional theory (DFT) calculations. The results demonstrate color-tunable CTE and near-white-light emission, highlighting the synergetic role of through-space conjugation, energy/charge transfer, and halogen atoms in the CTE mechanism. This study aims to unravel the mechanism of CTE in small-molecule CLgens and address the scarcity of reports on SCWL emission from nonconjugated luminogens, contributing to advancements in this field.