A thermally activated delayed fluorescence exciplex to achieve highly efficient and stable blue and green phosphorescent organic light-emitting diodes |
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Authors: | Dehai Dou Peng Wu Zhangcheng Liao Jian Hao Jianhua Zhang Zixing Wang |
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Affiliation: | Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University, 149 Yanchang Rd, 200072 P. R. China, Fax: +86-21-56333362, +86-21-56333362 ; Department of Chemistry, Shanghai University, 149 Yanchang Rd, 200072 P. R. China |
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Abstract: | The development of a thermally activated delayed fluorescence (TADF) exciplex with high energy is of great significance in achieving highly efficient blue, green, and red organic light-emitting diodes (OLEDs) for use in full-color displays and white lighting. Highly efficient and stable blue and green phosphorescent OLEDs were demonstrated by employing a TADF exciplex (energy: 2.9 eV) based on 4-substituted aza-9,9′-spirobifluorenes (aza-SBFs). Blue PhOLEDs demonstrated a maximum current efficiency (CE) of 47.9 cd A−1 and an external quantum efficiency (EQE) of 22.5% at 1300 cd m−2 (2.5 times the values of aza-SBF-based systems), with the best blue PhOLED demonstrating a CE, power efficiency (PE) and EQE of 60.3 cd A−1, 52.7 lm W−1, and 26.2%, respectively. Green PhOLEDs exhibited a CE of 78.1 cd A−1 and EQE of 22.5% at 9360 cd m−2, with the best green PhOLED exhibiting a maximum CE, PE, and EQE of 87.4 cd A−1, 101.6 lm W−1, and 24.5%, respectively. The device operational lifetime was improved over 17-fold compared to reference devices because of the high thermal stability of the materials and full utilization of the TADF exciplex energy, indicating their potential for application in commercial OLEDs.A high energy TADF exciplex (415 nm) based on aza-spirobifluorene derivatives was demonstrated to achieve efficient and stable PhOLEDs. |
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