Effect of fluorocarbon (trifluoromethyl groups) substitution on blue electroluminescent properties of 9,9′-bianthracene derivatives with twisted intramolecular charge-transfer excited states

• Quite high thermal stability and luminescence efficiency for OLED applications.
• 9,9′-Bianthracene derivatives with TICT-states to obtain high-efficiency electroluminescence.
• The meta-linkage BAn-(3)-CF3 based device exhibits excellent performance (5.88 cd A−1, 3.15%).
• The doped devices present an excellent efficiency stability.

By introducing a highly fluorescent 9,9′-bianthracene, fluorocarbon (trifluoromethyl groups) with the different linkage mode on the periphery of the 9,9′-bianthracene core, two novel blue-emissive materials (BAn-(3)-CF3 and BAn-(4)-CF3) were synthesized and characterized. The high luminescence efficiency and excellent stability rendered both promising materials in electroluminescent devices. The twisted intramolecular charge transfer state was demonstrated to enhance the occurrence of singlet excitons in the fluorescent emitter, which was based on the 9,9′-bianthracene moiety. Specifically, the meta-linkage BAn-(3)-CF3 device doped with sky blue fluorescent material 4,4-bis[4-(di-p-tolylamino)styryl]biphenyl showed that the singlet generation fraction was more than 25%, and presented an impressive luminous current efficiency of 5.88 cd A−1 and an external quantum efficiency of 3.15% with a high luminance of over 12,000 cd m−2. Noticeably, the para-linkage BAn-(4)-CF3 device exhibited an excellent efficiency stability with almost unchanged roll-off on the current and power efficiencies, even when the brightness approached 12,000 cd m−2.

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