RT Journal Article
SR Electronic
T1 Allochroic thermally activated delayed fluorescence diodes through field-induced solvatochromic effect
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP e1700904
DO 10.1126/sciadv.1700904
VO 3
IS 9
A1 Han, Chunmiao
A1 Duan, Chunbo
A1 Yang, Weibo
A1 Xie, Mingchen
A1 Xu, Hui
YR 2017
UL http://advances.sciencemag.org/content/3/9/e1700904.abstract
AB Allochroic organic light-emitting devices (AOLEDs) characterized by field-dependent emissive color variation are promising as visible signal response units for intelligent applications. Most of the AOLEDs were realized by changing their recombination zones or inter- and intramolecular energy transfer, rendering the limited repeatability, stability, and electroluminescence (EL) performance. We report a novel thermally activated delayed fluorescence (TADF) diode that featured a successive and irreversible emission color change from bluish green to deep blue during voltage increase, which uses the significant influence of host polarity on the emission color of TADF dyes, namely, solvatochromic effect. Its host 3,6-di-tert-butyl-1,8-bis(diphenylphosphoryl)-9H-carbazole (tBCzHDPO) was designed with remarkable field-dependent polarity reduction from 7.9 to 3.3 D by virtue of hydrogen bond–induced conformational isomerization. This TADF device achieves the best EL performance among AOLEDs, to date, with, for example, an external quantum efficiency beyond 15%, as well as the unique irreversible allochroic characteristic for visible data storage and information security.