Face-to-Face Orientation of Quasiplanar Donor and Acceptor Enables Highly Efficient Intramolecular Exciplex Fluorescence.
Intramolecular through-space charge-transfer (TSCT) excited states have been exploited for developing thermally activated delayed fluorescence (TADF) emitters, but the tuning of excited state dynamics by conformational engineering remains sparse. Designed here is a series of TSCT emitters with precisely controlled alignment of the donor and acceptor segments. With increasing intramolecular π-π interactions, the radiative decay rate of the lowest singlet excited state (S1 ) progressively increased together with a suppression of nonradiative decay, leading to significantly enhanced photoluminescence quantum yields of up to 0.99 in doped thin films. A high-efficiency electroluminescence device, with a maximum external quantum efficiency (EQE) of 23.96 %, was achieved and maintains >20 % at a brightness of 1000 cd m-2 . This work sheds light on the importance of conformation control for achieving high-efficiency intramolecular exciplex emitters.
['Wu|Chao|C|', 'Liu|Weiqiang|W|', 'Li|Kai|K|http://orcid.org/0000-0002-5869-1006', 'Cheng|Gang|G|', 'Xiong|Jinfan|J|', 'Teng|Teng|T|', 'Che|Chi-Ming|CM|', 'Yang|Chuluo|C|http://orcid.org/0000-0001-9337-3460']
fluorescence π-π interactions charge transfer donor-acceptor systems luminescence