Isomeric Thermally Activated Delayed Fluorescence Emitters for Color Purity-Improved Emission in Organic Light-Emitting Devices

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• 作者：Dong-Yang Chen ; Wei Liu ; Cai-Jun Zheng ; Kai Wang ; Fan Li ; Si−Lu Tao ; Xue-Mei Ou ; Xiao-Hong Zhang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：July 6, 2016
• 年：2016
• 卷：8
• 期：26
• 页码：16791-16798
• 全文大小：486K
• 年卷期：0
• ISSN：1944-8252

文摘

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.