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Molecular Design Approach Managing Molecular Orbital Superposition for High Efficiency without Color Shift in Thermally Activated Delayed Fluorescent Organic Light‐Emitting Diodes
Author(s) -
Kim Mounggon,
Yoon SeongJun,
Han Si Hyun,
Ansari Ramin,
Kieffer John,
Lee Jun Yeob,
Kim Jinsang
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805616
Subject(s) - homo/lumo , benzonitrile , quantum efficiency , fluorescence , common emitter , molecular orbital , photochemistry , materials science , oled , chemistry , optoelectronics , molecule , nanotechnology , optics , physics , organic chemistry , layer (electronics)
Molecular design principles of thermally activated delayed fluorescent (TADF) emitters having a high quantum efficiency and a color tuning capability was investigated by synthesizing three TADF emitters with donors at different positions of a benzonitrile acceptor. The position rendering a large overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) enhances the quantum efficiency of the TADF emitter. Regarding the orbital overlap, donor attachments at 2‐ and 6‐positions of the benzonitrile were more beneficial than 3‐ and 5‐substitutions. Moreover, an additional attachment of a weak donor at the 4‐position further increased the quantum efficiency without decreasing the emission energy. Therefore, the molecular design strategy of substituting strong donors at the positions allowing a large molecular orbital overlap and an extra weak donor is a good approach to achieve both high quantum efficiency and a slightly increased emission energy.