PT  - JOURNAL ARTICLE
AU  - Han, Chunmiao
AU  - Duan, Chunbo
AU  - Yang, Weibo
AU  - Xie, Mingchen
AU  - Xu, Hui
TI  - Allochroic thermally activated delayed fluorescence diodes through field-induced solvatochromic effect
AID  - 10.1126/sciadv.1700904
DP  - 2017 Sep 01
TA  - Science Advances
PG  - e1700904
VI  - 3
IP  - 9
4099  - http://advances.sciencemag.org/content/3/9/e1700904.short
4100  - http://advances.sciencemag.org/content/3/9/e1700904.full
SO  - Sci Adv2017 Sep 01; 3
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.