Origin of improved stability in green phosphorescent organic light-emitting diodes based on a dibenzofuran/spirobifluorene hybrid host
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A highly efficient and stable green phosphorescent organic light-emitting diode (PHOLED) was fabricated by using a new dibenzofuran/spirobifluorene hybrid material (named as DBFSF2) as the host material. The DBFSF2-based PHOLEDs exhibited slightly better electroluminescence efficiency than that in the conventional host material 4,4′-bis(carbazol-9-yl)biphenyl (CBP)-based ones. Moreover, further studies demonstrated that the DBFSF2-based PHOLEDs had a better stability with about 1.5 times improvement in half lifetime compared with that of CBP-based ones. To investigate the mechanism behind the enhanced stability in the DBFSF2-based PHOLEDs, the evaluations of dark spots growth, film crystallization properties and carrier recombination zone were carried out.
KeywordsAcac High Occupied Molecular Orbital Current Efficiency Host Material Triplet Energy
We acknowledge financial support from the Natural Science Foundation of China (Nos. 61036009, 61177016, 21161160446, and 61307036), the National High-Tech Research Development Program (No. 2011AA03A110), the Natural Science Foundation of Jiangsu Province (No. BK2010003, BK20130288), and the Key University Science Research Project of Jiangsu Province (12KJB510028). This is also a project funded by Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), and by the Fund for Excellent Creative Research Teams of Jiangsu Higher Education Institutions.
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