Manipulation of Hole and Exciton Distributions in Organic Light-Emitting Diodes with Dual Emission Layers

IF 2.1 4区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Electronic Materials Letters Pub Date : 2023-08-23 DOI:10.1007/s13391-023-00452-1

Suk-Ho Song, Jae-In Yoo, Hyo-Bin Kim, Sung-Cheon Kang, Kanghoon Kim, Sung-Jae Park, Qun Yan, Jang-Kun Song

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Abstract

The efficiency improvement of organic light-emitting diodes (OLEDs) is important but challenging. Here, we introduce a unique OLED with a hole modulation layer (HML) in the middle of its emission layer (EML). The external quantum efficiency and power efficiency can be improved by approximately 58% when an HML with optimized thickness is inserted. HML insertion can efficiently retard hole flow, thus improving (i) exciton distribution uniformity and (ii) local electron–hole charge balance. A systematic study of the individual contributions of two EMLs separated by the HML shows that the former factor dominantly works at low current densities (< 10 mA/cm²), whereas the latter factor functions over the entire current density range of the OLED. Therefore, the efficiency improvement is greatest at low current densities, which aligns with the typical operating range in display applications. The results provide a deeper understanding of the OLED emission mechanism, and the proposed OLED structure can significantly benefit high-performance OLED displays.

Graphical Abstract

Abstract Image

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双发射层有机发光二极管中空穴和激子分布的操纵

提高有机发光二极管（OLED）的效率非常重要，但也极具挑战性。在这里，我们引入了一种独特的有机发光二极管，在其发射层（EML）中间有一个空穴调制层（HML）。当插入具有优化厚度的 HML 时，外部量子效率和功率效率可提高约 58%。插入 HML 可以有效地延缓空穴流，从而改善（i）激子分布均匀性和（ii）局部电子-空穴电荷平衡。对被 HML 分隔开来的两个 EML 的各自贡献进行的系统研究表明，前一个因素主要在低电流密度（10 mA/cm2）时起作用，而后一个因素则在 OLED 的整个电流密度范围内起作用。因此，在低电流密度时效率提高最大，这与显示应用中的典型工作范围一致。这些结果加深了人们对 OLED 发射机制的理解，而所提出的 OLED 结构可显著提高高性能 OLED 显示屏的性能。

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来源期刊

Electronic Materials Letters 工程技术-材料科学：综合

CiteScore

4.70

自引率

20.80%

发文量

审稿时长

2.3 months

期刊介绍： Electronic Materials Letters is an official journal of the Korean Institute of Metals and Materials. It is a peer-reviewed international journal publishing print and online version. It covers all disciplines of research and technology in electronic materials. Emphasis is placed on science, engineering and applications of advanced materials, including electronic, magnetic, optical, organic, electrochemical, mechanical, and nanoscale materials. The aspects of synthesis and processing include thin films, nanostructures, self assembly, and bulk, all related to thermodynamics, kinetics and/or modeling.