In:
Advanced Functional Materials, Wiley, Vol. 28, No. 7 ( 2018-02)
Abstract:
Actualizing highly efficient solution‐processed thermally activated delayed fluorescent (TADF) organic light‐emitting diodes (OLEDs) at high brightness becomes significant to the popularization of purely organic electroluminescence. Herein, a highly soluble emitter benzene‐1,3,5‐triyltris((4‐(9,9‐dimethylacridin‐10(9 H )‐yl)phenyl)methanone was developed, yielding high delayed fluorescence rate ( k TADF 〉 10 5 s −1 ) ascribed to the multitransition channels and tiny singlet–triplet splitting energy (Δ E ST ≈ 32.7 meV). The triplet locally excited state is 0.38 eV above the lowest triplet charge‐transfer state, assuring a solely thermal equilibrium route for reverse intersystem crossing. Condensed state solvation effect unveils a hidden “trade‐off”: the reverse upconversion and triplet concentration quenching processes can be promoted but with a reduced radiative rate from the increased dopant concentration and the more polarized surroundings. Striking a delicate balance, corresponding vacuum‐evaporated and solution‐processed TADF‐OLEDs realized maximum external quantum efficiencies (EQEs) of ≈26% and ≈22% with extremely suppressed efficiency roll‐off. Notably, the wet‐processed one achieves to date the highest EQEs of 20.7%, 18.5%, 17.1%, and 13.6%, among its counterparts at the luminance of 1000, 3000, 5000, and 10 000 cd m −2 , respectively.
Type of Medium:
Online Resource
ISSN:
1616-301X
,
1616-3028
DOI:
10.1002/adfm.201704927
Language:
English
Publisher:
Wiley
Publication Date:
2018
detail.hit.zdb_id:
2029061-5
detail.hit.zdb_id:
2039420-2
SSG:
11
Permalink