Remote Steric Effect as a Facile Strategy for Improving the Efficiency of Exciplex-Based OLEDs.
This work reports a new strategy of introducing remote steric effect onto the electron donor for giving the better performance of the exciplex-based organic light-emitting device (OLED). The bulky triphenylsilyl group (SiPh3) was introduced onto the fluorene bridge of 4,4'-(9H-fluorene-9,9-diyl)bis(N,N-di-p-tolylaniline) (DTAF) to create remote steric interactions for increasing the possibility of effective contacts between electron-donating chromophores and acceptor molecules, rendering the resulting exciplex to have a higher photoluminescence quantum yield (PLQY). The green exciplex device based on DSDTAF:3N-T2T (1:1) as an emitting layer exhibits a low turn-on voltage of 2.0 V, high maximum efficiencies (13.2%, 42.9 cd A-1, 45.5 lm W-1), which are higher than the device employed DTAF (without SiPh3groups) (11.6%, 35.3 cd A-1, 41.3 lm W-1) as donor under the same device structure. This strategy was further examined for blue exciplex, where the EQE was enhanced from 9.5% to 12.5% as the electron acceptor PO-T2T mixed with a tert-butyl group substituted carbazole-based donor (CPTBF) as the emitting exciplex in device. This strategy is simple and useful for developing high performance exciplex OLEDs.
Institute of Optoelectronic Sciences, National Taiwan Ocean University , Keelung 202, Taiwan.
Wen-Yi
http://orcid.org/0000-0003-1761-2743
WY
Hung
Department of Chemistry, National Taiwan University , Taipei 106, Taiwan.
Ting-Chih
TC
Wang
Institute of Optoelectronic Sciences, National Taiwan Ocean University , Keelung 202, Taiwan.
Pin-Yi
PY
Chiang
Department of Chemistry, National Taiwan University , Taipei 106, Taiwan.
Bo-Ji
BJ
Peng
Department of Chemistry, National Taiwan University , Taipei 106, Taiwan.|Institute of Atomic and Molecular Science , Taipei 106, Taiwan.
Ken-Tsung
KT
Wong
bulky substitution; exciplex; intermolecular charge transfer; remote steric effect; thermally activated delayed fluorescence (TADF)