Long-Persistent High-Temperature Phosphorescence of Zero-Dimensional Metal Halide Hybrid for Temperature-Sensitive Anticounterfeiting

Solid-state materials with long-persistence phosphorescence always suffer serious thermal quenching effect that greatly hinders their applications at high-temperature conditions (>373 K). Therefore, developing high-temperature phosphorescence (HTP) materials remains a great challenge. In this work, cytosine (Cyt) is hybridized with indium chloride into zero-dimensional (Cyt)2[InCl5·H2O] (CICH). A green afterglow up to 1.0 s is observed at room temperature for CICH but almost quenched at 448 K due to the serious thermal quenching effect. Upon removing the coordinated H2O molecules of CICH (denoted to CIC), CIC shows an excellent performance of HTP with a persistence time of 0.4 s even at 448 K. The greatly improved thermal resistance is attributed to the removal of coordinated H2O molecules, which leads to a reduced free volume of Cyt, thereby suppressing the molecular vibration and rotation. Additionally, the afterglow time of CICH can be facilely tailored through Sb3+ doping due to efficient triplet energy transfer. At last, given the high thermal tolerance of CIC, a temperature-sensitive anticounterfeiting is successfully demonstrated.