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P‐183: Development of Highly Efficient Long Wavelength Thermally Activated Delayed Fluorescent Organic Light‐Emitting Diodes Using an Auxiliary Acceptor as Reverse Intersystem Crossing Promoter
Author(s) -
Kothavale Shantaram Sahadu,
Chung Won Jae,
Lee Jun Yeob
Publication year - 2020
Publication title -
sid symposium digest of technical papers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.351
H-Index - 44
eISSN - 2168-0159
pISSN - 0097-966X
DOI - 10.1002/sdtp.14326
Subject(s) - intersystem crossing , homo/lumo , acceptor , fluorescence , singlet state , photochemistry , phosphorescence , materials science , oled , quantum efficiency , chemistry , optoelectronics , atomic physics , molecule , excited state , optics , physics , nanotechnology , layer (electronics) , condensed matter physics , organic chemistry
To achieve high efficiency for long wavelength thermally activated delayed fluorescent emitter is difficult because small singlet emission energy and high fluorescence radiative rate are contradictory to each other, as per energy gap law. We designed and synthesized two yellow‐red TADF emitters namely, Ac‐DCQX‐1 and Ac‐DCQX‐2 based on a molecular design concept of inserting auxiliary acceptor to the main acceptor unit. Auxiliary acceptor was introduced at the ortho position of the acridine donor for the intensified charge transfer character from donor to acceptor, increased HOMO‐LUMO overlap and reduced singlet‐triplet energy gap. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of Ac‐DCQX‐1 andAc‐DCQX‐2 were −5.87/−3.49 and −5.89/−3.87 eV respectively andthe singlet‐triplet energy gap (ΔE ST ) calculated were 0.08/0.05 eV. As a result, high EQE values of 27.6 and 23.8 % with color coordinate of (0.42, 0.55) and (0.55, 0.44) were obtained for Ac‐DCQX‐1 and Ac‐DCQX‐2 respectively.