Chrysene and triphenylene based-fluorophores as non-doped deep blue emitters for triplet-triplet annihilation organic light-emitting diodes

Herein, two new triplet-triplet annihilation (TTA) molecules, namely CCsCN and CTpCN , based on chrysene and triphenylene polyaromatic rings to develop deep-blue emissive materials for efficient non-doped TTA-OLEDs are designed, and synthesized. The polyaromatic rings are directly functionalized with benzonitrile and electron donating 9-(m-tolyl)carbazole moieties. Their structural, physical, and photophysical properties are experimentally and theoretically studied. Both molecules display deep blue color emissions in solution and neat films with decent hole mobility and high thermal and electrochemical stabilities. They are effectively fabricated as non-doped emitters in the OLEDs, and all devices exhibit deep blue electroluminescence (EL) spectra (CIEy = 0.08) with narrow full width at half maximum of 74 nm, low turn-on voltages of 3.0 V and TTA characteristics. In particular, the CCsCN-based device achieves the best EL performance with a maximum luminance (L-max) of 6338 cd m(-2) , a maximum external quantum efficiency (EQE(max)) of 3.33%, and a maximum current efficiency (CEmax) of 2.64 cd A(-1).

Automated summary

In this study, two new triplet-triplet annihilation (TTA) molecules have been designed and synthesized for the development of efficient deep-blue emissive materials. Experimental and theoretical studies have demonstrated that both molecules exhibit excellent photophysical properties and stability in solution and films. The CCsCN-based device shows the best electroluminescence performance.