Designing a Deep Blue Emitter by Disrupting Phenanthroimidazole Conjugation for Non-Doped OLEDs with an External
Mingke Li1, Yu Huang1, Yue Yu1
1Institute of Polymer Optoelectronic Materials and Devices, Guangdong Basic Research Center of Excellence for Energy and Information Polymer Materials, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, P. R. China.
Abstract:
The pursuit of highly efficient non-doped organic light-emitting diodes (OLEDs) has promoted the development of blue emitters with a design strategy. In this study, we developed a deep blue emitter featuring hybridized local and charge-transfer characteristics. The blue emitter, PIMAnCz, consists of a molecular framework of a disrupted phenanthroimidazole moiety, which resulted in large steric hindrance and reduced electron delocalization along the fragments. These features lead to a high spin-orbit coupling between the high-lying triplet level and low-lying singlet level (S1) and a photoluminescence of 59%. More importantly, the non-doped device employing a neat PIMAnCz emitting layer delivered a maximum external quantum efficiency of 13.19% with Commission Internationale de l'Eclairage (CIE) coordinates of (0.15, 0.09), placing it among the highest efficiencies attained for a non-doped deep blue OLED with CIEy < 0.10. These findings provide practical design insights for a highly efficient blue emitter for non-doped deep blue OLED applications.
