Thermally Activated Delayed Fluorescence in CuI Complexes Originating from Restricted Molecular Vibrations

• Published in: Chemistry : a European journal Vol. 23; no. 49; pp. 11761 - 11766
• Main Authors: Li, Guangfu, Nobuyasu, Roberto S., Zhang, Baohua, Geng, Yun, Yao, Bing, Xie, Zhiyuan, Zhu, Dongxia, Shan, Guogang, Che, Weilong, Yan, Likai, Su, Zhongmin, Dias, Fernando B., Bryce, Martin R.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 04.09.2017; John Wiley and Sons Inc
• Subjects: Agglomeration; aggregation-induced emission; Chemistry; Communication; Communications; copper; Cu(I) complexes; Design engineering; Emission measurements; Emissivity; Emitters; Fluorescence; Luminescence; Optical properties; photophysical properties; thermally activated delayed fluorescence; Vibrations
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201701862

The mechanism of thermally activated delayed fluorescence (TADF) in molecules in aggregated or condensed solid states has been rarely studied and is not well understood. Nevertheless, many applications of TADF emitters are strongly affected by their luminescence properties in the aggregated state. In this study, two new isomeric tetradentate CuI complexes which simultaneously show aggregation induced emission (AIE) and TADF characteristics are reported for the first time. We provide direct evidence that effectively restricting the vibrations of individual molecules is a key requisite for TADF in these two CuI complexes through in‐depth photophysical measurements combined with kinetic methods, single crystal analysis and theoretical calculations. These findings should stimulate new molecular engineering endeavours in the design of AIE–TADF active materials with highly emissive aggregated states. Turn on the lights: Two new isomeric AIE–TADF active CuI complexes have been studied. Direct evidence that aggregation is able to promote TADF by suppressing vibrational quenching in these two CuI complexes is provided. Phosphorescence and TADF could be realized, respectively in doping with two different matrix PMMA films due to different degrees of restricting molecular vibrations. These findings could open a new avenue in the design of AIE–TADF active materials.