A thermally activated delayed fluorescence exciplex to achieve highly efficient and stable blue and green phosphorescent organic light-emitting diodes

Dehai Dou; Peng Wu; Zhangcheng Liao; Jian Hao; Jianhua Zhang; Zixing Wang

doi:10.1039/c9ra02875g

A thermally activated delayed fluorescence exciplex to achieve highly efficient and stable blue and green phosphorescent organic light-emitting diodes

RSC Adv. 2019 Jul 31;9(41):23810-23817. doi: 10.1039/c9ra02875g. eCollection 2019 Jul 29.

Authors

Dehai Dou^{1

2}, Peng Wu^{1

2}, Zhangcheng Liao^{1

2}, Jian Hao², Jianhua Zhang¹, Zixing Wang¹

Affiliations

¹ Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University 149 Yanchang Rd 200072 P. R. China zxwang78@shu.edu.cn jhzhang@shu.edu.cn +86-21-56333362 +86-21-56333362.
² Department of Chemistry, Shanghai University 149 Yanchang Rd 200072 P. R. China.

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.