Negative thermal quenching of photoluminescence in a copper–organic framework emitter
Ting Wu, Shenlong Jiang, Pabitra Narayan Samanta, Yangbin Xie, Jipeng Li, Xiaoling Wang, Majumdar Devashis, Xiangwei Gu, Yusong Wang, Wei Huang, Qun Zhang, Jerzy Leszczyński, Dayu Wu
Abstract
Negative thermal quenching (NTQ), an abnormal phenomenon that the intensity of photoluminescence (PL) increases with increasing temperature, has essentially been restricted to either bulk semiconductors or very low temperatures. Here, we report a delayed fluorescence copper-organic framework exhibiting negative thermal quenching (NTQ) of photoluminescence, which is driven by the fluctuation between the localized and delocalized form of its imidazole ligand. The process is completely reversible on cooling/heating cycles. This study opens a new avenue to explore the electronically switchable NTQ effect in coordination networks and further to develop the NTQ-based light-emitting diodes.