Exciton dynamics of an aggregation-induced delayed fluorescence emitter in non-doped OLEDs and its application as host for high-efficiency red phosphorescent OLEDs

Hanlin Li; Chengwei Lin; Yibing Wu; Xianfeng Qiao; Dezhi Yang; Yanfeng Dai; Qian Sun; Tansir Ahamad; Zhujin Zhao; Dongge Ma

doi:10.1039/d3cp03275b

Exciton dynamics of an aggregation-induced delayed fluorescence emitter in non-doped OLEDs and its application as host for high-efficiency red phosphorescent OLEDs

Phys Chem Chem Phys. 2023 Oct 11;25(39):26878-26884. doi: 10.1039/d3cp03275b.

Authors

Affiliations

¹ Institute of Polymer Optoelectronic Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China. mszjzhao@scut.edu.cn.
² Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.

PMID: 37782517
DOI: 10.1039/d3cp03275b

Abstract

Aggregation-induced delayed fluorescence (AIDF) materials have great potential in non-doped OLEDs due to their high photoluminescence (PL) quantum efficiency in film, high exciton utilization in the aggregated state and negligible efficiency roll-off at high luminance. However, their efficient mechanism in OLEDs is not yet well understood. Here, the exciton dynamics are used to investigate the electroluminescence (EL) mechanism of an AIDF emitter (4-(10H-phenoxazin-10-yl)phenyl)-(9-phenyl-9H-carbazol-3-yl)methanone (CP-BP-PXZ) in detail. It can be seen that the high efficiency and negligible efficiency roll-off in non-doped OLEDs based on CP-BP-PXZ as the emitter are ascribed to the effective reverse intersystem crossing (RISC) from high level triplet T₂ to singlet S₁ in the aggregated state. Furthermore, CP-BP-PXZ also exhibits excellent properties as a phosphor host due to its good AIDF properties. Thus, high-efficiency red phosphorescent OLEDs with low roll-off efficiency are successfully fabricated based on CP-BP-PXZ as the host. The maximum external quantum efficiency (EQE_max) reaches 23% and is maintained at 21% at a luminance of 1000 cd m^-2.