Isomeric Thermally Activated Delayed Fluorescence Emitters for Color Purity-Improved Emission in Organic Light-Emitting Devices.
To improve the color purity of thermally activated delayed fluorescence (TADF) emitters, two isomeric compounds, oPTC (5'-(phenoxazin-10-yl)-[1,1':3',1″-terphenyl]-2'-carbonitrile) and mPTC (2'-(phenoxazin-10-yl)-[1,1':3',1″-terphenyl]-5'-carbonitrile), were designed and synthesized with same skeleton but different molecular restrictions. Both compounds exhibit similar highest occupied molecular orbital and lowest unoccupied molecular orbital distributions and energy levels, photophysical properties in nonpolar cyclohexane solution, and high external quantum efficiencies (19.9% for oPTC and 17.4% for mPTC) in the devices. With the increased molecular space restriction induced by the additional phenyl substitutions at meta-position of the cyano group from mPTC to oPTC, much weaker positive solvatochromic effect is observed for mPTC. And the color purity of emission from mPTC (full width at half-maximum (fwhm) of 86 nm) is also improved contrasted with that of oPTC (fwhm of 97 nm) in the devices. These results prove that increased restriction of the molecular structure is a simple and effective method to improve the color purity of the TADF emitters.
Institute of Functional Nano & Soft Materials, Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China.|Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Dong-Yang
DY
Chen
Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|College of Materials Science and Engineering, Beijing Institute of Technology , Beijing 100081, P. R. China.
Wei
W
Liu
Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|School of Optoelectronic Information, University of Electronic Science and Technology of China , Chengdu 610054, P. R. China.
Cai-Jun
CJ
Zheng
Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Kai
K
Wang
Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Fan
F
Li
School of Optoelectronic Information, University of Electronic Science and Technology of China , Chengdu 610054, P. R. China.
Si Lu
SL
Tao
Institute of Functional Nano & Soft Materials, Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China.|Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Xue-Mei
XM
Ou
Institute of Functional Nano & Soft Materials, Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China.|Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Xiao-Hong
XH
Zhang
OLEDs; TADF; color purity; fwhm; isomeric compounds