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π‐Extended Carbazole Derivatives as Host Materials for Highly Efficient and Long‐Life Green Phosphorescent Organic Light‐Emitting Diodes
Author(s) -
Arai Ayato,
Sasabe Hisahiro,
Nakao Kohei,
Masuda Yuki,
Kido Junji
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202005144
Subject(s) - oled , carbazole , phosphorescence , materials science , diode , optoelectronics , fluorescence , phosphorescent organic light emitting diode , biphenyl , electroluminescence , photochemistry , nanotechnology , chemistry , optics , organic chemistry , physics , layer (electronics)
High‐performance organic light‐emitting diodes (OLEDs) that use phosphorescent and/or thermally activated delayed fluorescence emitters are capable of realizing 100 % electron‐to‐photon conversion. The host materials in these OLEDs play crucial roles in determining OLED performance. Carbazole derivatives are frequently used as host materials, among which 3,3‐bis(9 H ‐carbazol‐9‐yl)biphenyl ( mCBP ) is often used for lifetime testing in scientific studies. In this study, the π conjugation of the carbazole unit was expanded to enhance OLED lifetime by designing and developing two benzothienocarbazole (BTCz)‐based host materials, namely m1BTCBP and m4BTCBP . Among these host materials, m1BTCBP formed a highly efficient [Ir(ppy) 3 ]‐based OLED with an operational luminescence half‐life (LT 50 ) of over 300 h at an initial luminance of approximately 12000 cd m −2 (current density: 25 mA cm −2 ). The LT 50 value at 1000 cd cm −2 was estimated to be about 23 000 h. This performance is clearly higher than that of mCBP ‐based OLEDs (LT 50 ≈8500 h).