Deep Blue Electroluminescence from an Asymmetrically Twisted and Rigid Phenanthroimidazole Molecule

doi:10.7517/j.issn.1674-0475.2017.04.032

Abstract

Abstract:

Efficient deep-blue organic emitters are of particular significance in organic electroluminescence. In this work, by using an asymmetrically twisted and rigid molecular design strategy, a high-efficiency deep-blue bisphenanthroimidazole emitter, MBTPI, was successfully synthesized, characterized and applied in a high-performance deep-blue organic light-emitting device (OLED). It shows high decomposition temperature (496℃) and high glass transition temperature (190℃), which are favorable for device stability. Its molecular conjugation was efficiently controlled by an asymmetrically twisted and rigid molecular structure, which makes its emission band locates at deep blue region, and solid film emission quantum yield is as high as 74%. Theoretical calculation also proves the presence of asymmetrically twisted rigid molecular structure, and the methyl dose change the molecular geometry, but has little influence on frontier orbital distribution, which is beneficial for maintaining good bipolar transporting property. MBTPI-based non-doped OLED displays a stable and highly efficient deep-blue electroluminescence with CIE coordinates (0.15, 0.07), which is very close to the NTSC deep-blue standard (0.14, 0.08). External quantum efficiency is high up to 4.91%, which is comparable to the state-of-the-art deep-blue non-doped OLEDs with CIE_y lower than 0.08.

Key words: phenanthroimidazole, deep-blue emission, organic light-emitting material, non-doped device

CHEN Wen-Cheng, LEE Chun-Sing, TONG Qing-Xiao. Deep Blue Electroluminescence from an Asymmetrically Twisted and Rigid Phenanthroimidazole Molecule[J]. Imaging Science and Photochemistry, 2017, 35(5): 720-728.

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