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Vol. 14 (2022)

Cavity-Suppressing Electrode Integrated with Multi-Quantum Well Emitter: A Universal Approach Toward High-Performance Blue TADF Top Emission OLED

https://doi.org/10.1007/s40820-022-00802-y
Il Gyu Jang
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea
Vignesh Murugadoss
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea
Tae Hoon Park
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea
Kyung Rock Son
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea
Ho Jin Lee
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea
WanQi Ren
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea
Min Ji Yu
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea
Tae Geun Kim
School of Electrical Engineering, Korea University, Anam‑ro 145, Seongbuk‑gu, Seoul 02841, Republic of Korea

Corresponding Author: Tae Geun Kim

tgkim1@korea.ac.kr

Nano-Micro Letters, Vol. 14 (2022), Article Number: 60

Abstract

A novel device structure for thermally activated delayed fluorescence (TADF) top emission organic light-emitting diodes (TEOLEDs) that improves the viewing angle characteristics and reduces the efficiency roll-off is presented. Furthermore, we describe the design and fabrication of a cavity-suppressing electrode (CSE), Ag (12 nm)/WO3 (65 nm)/Ag (12 nm) that can be used as a transparent cathode. While the TADF-TEOLED fabricated using the CSE exhibits higher external quantum efficiency (EQE) and improved angular dependency than the device fabricated using the microcavity-based Ag electrode, it suffers from low color purity and severe efficiency roll-off. These drawbacks can be reduced by using an optimized multi-quantum well emissive layer (MQW EML). The CSE-based TADF-TEOLED with an MQW EML fabricated herein exhibits a high EQE (18.05%), high color purity (full width at half maximum ~ 59 nm), reduced efficiency roll-off (~ 46% at 1000 cd m−2), and low angular dependence. These improvements can be attributed to the synergistic effect of the CSE and MQW EML. An optimized transparent CSE improves charge injection and light outcoupling with low angular dependence, and the MQW EML effectively confines charges and excitons, thereby improving the color purity and EQE significantly. The proposed approach facilitates the optimization of multiple output characteristics of TEOLEDs for future display applications.


Highlights:


1 A blue thermally activated delayed fluorescence top-emission organic light-emitting diode (TEOLED) structure that combines a cavity-suppressing transparent electrode and a multi-quantum-well emissive layer is proposed.
2 The TEOLED exhibits high external quantum efficiency (18.05%), high color purity (full width at half maximum ~ 59 nm), reduced efficiency roll-off (~ 46% at 1000 cd m−2), and low angular dependence

Keywords

Cavity suppression Multi-quantum well Viewing angle Efficiency roll-off Top emission OLED
Jang, Il Gyu, Vignesh Murugadoss, Tae Hoon Park, Kyung Rock Son, Ho Jin Lee, WanQi Ren, Min Ji Yu, and Tae Geun Kim. 2022. “Cavity-Suppressing Electrode Integrated With Multi-Quantum Well Emitter: A Universal Approach Toward High-Performance Blue TADF Top Emission OLED”. Nano-Micro Letters 14 (February):60. https://doi.org/10.1007/s40820-022-00802-y.
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