Realization of Efficient Phosphorescent Organic Light-Emitting Devices Using Exciplex-Type Co-Host.

Lishuang Wu,Huiwen Xu,Huishan Yang

doi:10.3390/mi13010051

Lishuang Wu, Huiwen Xu + Show 1 more

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https://doi.org/10.3390/mi13010051

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Journal: Micromachines	Publication Date: Dec 29, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Quanzhou Normal University, Huaqiao University

Abstract

High-performance phosphorescent organic light-emitting devices with an exciplex-type co-host were fabricated. The co-host is constituted by 1,3,5-tris(N-phenylbenzimidazol-2-yl) benzene, and 4,4,4-tris (N-carbazolyl) triphenylamine, and has obvious virtues in constructing efficient devices because of the thermally activated delayed fluorescence (TADF) resulting from a reverse intersystem crossing (RISC) process. The highest external quantum efficiency and luminance are 14.60% and 100,900 cd/m2 for the optimal co-host device. For comparison, 9.22% and 25,450 cd/m2 are obtained for a device employing 4,4,4-tris (N-carbazolyl) triphenylamine as a single-host. Moreover, the efficiency roll-off is notably alleviated for the co-host device, indicated by much higher critical current density of 327.8 mA/cm2, compared to 120.8 mA/cm2 for the single-host device. The alleviation of excitons quenching resulting from the captured holes and electrons, together with highly sufficient energy transfer between the co-host and phosphorescent dopant account for the obvious boost in device performances.

Highlights

IntroductionPhosphorescent organic light-emitting devices (PHOLEDs) have tremendous potential in solid-state lighting and flat-panel displays due to the exciton utilization efficiency of
Phosphorescent organic light-emitting devices (PHOLEDs) have tremendous potential in solid-state lighting and flat-panel displays due to the exciton utilization efficiency of100% in theory realized by harvesting both the singlet and singlet excitons for electroluminescence devices [1]
We introduced an exciplex-type co-host consisting of a donor of 4,4,4-tris (N-carbazolyl) triphenylamine (TCTA) and an acceptor of 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBI) to fabricate efficient yellow phosphorescent OLEDs

Summary

Introduction

Phosphorescent organic light-emitting devices (PHOLEDs) have tremendous potential in solid-state lighting and flat-panel displays due to the exciton utilization efficiency of. Exciplex-type co-hosts composed of acceptors and donors have been employed in highly efficient phosphorescent OLEDs, derived from their unique advantages of improved charge balance and exciton utilization [11]. We introduced an exciplex-type co-host consisting of a donor of 4,4,4-tris (N-carbazolyl) triphenylamine (TCTA) and an acceptor of 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBI) to fabricate efficient yellow phosphorescent OLEDs. The TADF effect was solidly confirmed using the time-resolved photoluminescence spectra technology. The TADF effect was solidly confirmed using the time-resolved photoluminescence spectra technology Employing this exciplex-type co-host, we realized a high-performance yellow phosphorescent OLED with a maximum external quantum efficiency of 14.60%, and a power efficiency of 45.9 lm/W. The maximum luminance of the co-host device reaches 100,900 cd/m2 , about four times that of the single device

Experimental Details

Results and Discussion

Conclusions