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

Guangfu Li; Roberto S Nobuyasu; Baohua Zhang; Yun Geng; Bing Yao; Zhiyuan Xie; Dongxia Zhu; Guogang Shan; Weilong Che; Likai Yan; Zhongmin Su; Fernando B Dias; Martin R Bryce

doi:10.1002/chem.201701862

Thermally Activated Delayed Fluorescence in Cu^I Complexes Originating from Restricted Molecular Vibrations

Chemistry. 2017 Sep 4;23(49):11761-11766. doi: 10.1002/chem.201701862. Epub 2017 Aug 10.

Authors

Affiliations

¹ Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Street No. 5268, Changchun, 130024, P. R. China.
² Physics Department, Durham University, Durham, DH1 3LE, UK.
³ State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
⁴ Chemistry Department, Durham University, Durham, DH1 3LE, UK.

Abstract

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 Cu^I 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 Cu^I 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.

Keywords: Cu(I) complexes; aggregation-induced emission; copper; photophysical properties; thermally activated delayed fluorescence.