High-refractive-index capping layer improves top-light-emitting device performance

Hu, Baohua; Chen, Haifeng; Li, Chong; Huang, Wei; Ichikawa, Musubu

doi:10.1364/ao.391419

Cited by 7 publications

(10 citation statements)

References 42 publications

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“…However, they have a refractive index of about 1.8-1.9, which is too low to make them suitable for CPL application. A suitable alternative is metal oxide due to its high refractive index > 2.0 [79]. The most common metal oxide materials are molybdenum oxide (MoO 3 ) and tungsten oxide (WO 3 ), because they can be evaporated by the thermal evaporation method.…”

Section: Capping Layer (Cpl)mentioning

confidence: 99%

Technical status of top-emission organic light-emitting diodes

Kim

Lampande

Kwon

2021

Journal of Information Display

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Top-emission organic light-emitting diodes (TEOLEDs) that contain semi-transparent metal top cathodes and highly reflective anodes have been actively researched for display applications due to their many advantages such as their high aperture ratio, good color purity, and high efficiency. In this research, the technical design of TEOLEDs used in organic light-emitting diode (OLED) displays is reviewed, covering the optical theory with the microcavity effect, optical losses, and the importance of the Purcell effect in the optical calculation. The key methodologies for addressing the high efficiency and low driving voltage of TEOLEDs are also discussed.

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Section: Capping Layer (Cpl)mentioning

confidence: 99%

Technical status of top-emission organic light-emitting diodes

Kim

Lampande

Kwon

2021

Journal of Information Display

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“…Colloidal quantum dots (QDs) are spotlighted as one of the most promising emitting materials for optoelectronic devices owing to their advantages, such as high photoluminescence (PL) quantum semi-transparent top metal electrode. [21,22] The well-known effects and advantages of using a CPL are that it enables to modulate the optical interference in the cavity structure by tuning the CPL thickness. [23] When optimized, the light extraction to the normal direction can be enhanced and the FWHM can be narrowed down.…”

Section: Introductionmentioning

confidence: 99%

“…Also, the angle-dependent color shift can be mitigated through optimization. [22] Nevertheless, there is a strong trade-off relationship between the device efficiency and the angular spectral shifts in top-emission devices, mainly due to the intense microcavity resonance. [19,20] In 2017, Tan et al developed a multi-object algorithm that helps to precisely tune the optimal CPL conditions for lower spectral shifts, higher device efficiency, and wider color gamut, [24] resulting in broad application to top-emitting OLEDs.…”

Section: Introductionmentioning

confidence: 99%

Angle‐Independent Top‐Emitting Quantum‐Dot Light‐Emitting Diodes Using a Solution‐Processed Subwavelength Scattering–Capping Layer

Lee,

Kim

et al. 2024

Advanced Optical Materials

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Owing to the excellent optoelectronic properties of colloidal quantum dots (QDs), light‐emitting diodes based on QDs (QLEDs) have been considered one of the most promising electroluminescence (EL) devices for full‐color displays with a wide color gamut. Particularly, top‐emission device architecture has been of interest to both academia and industry, because of the advantages in light outcoupling, aperture ratios, and integration with conventional backplanes. In this structure, however, angle‐dependent color shifts originating from a variation in microcavity length are a critical issue that needs to be resolved. Here, a solution‐processed dual‐functional scattering–capping layer (SCPL) using ZnO nanoparticles on top‐emitting QLEDs with ZnSeTe/ZnSe/ZnS QDs to modulate the optical interference is presented. By precisely controlling the thickness of the SCPL, the EL intensity and spectrum can be redistributed to produce a uniform color from any viewing angle. It is discovered that, unlike conventional CPLs, the formation of random nanocracks and nanoclusters in the SCPL adds subwavelength light‐scattering capabilities, which promotes light extraction. The QLEDs with the solution‐processed SCPL exhibit a 44% increase in the maximum external quantum efficiency, with completely imperceptible angle‐dependent spectral shifts. The SCPL is expected to be applied to the development of high‐performance and next‐generation QLED displays.

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mentioning

confidence: 99%

Top‐Emitting Quantum Dot Light‐Emitting Diodes: Theory, Optimization, and Application

Lee

Seo

et al. 2023

Small Methods

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The superior optical properties of colloidal quantum dots (QDs) have garnered significant broad interest from academia and industry owing to their successful application in self‐emitting QD‐based light‐emitting diodes (QLEDs). In particular, active research is being conducted on QLEDs with top‐emission device architectures (TQLEDs) owing to their advantages such as easy integration with conventional backplanes, high color purity, and excellent light extraction. However, due to the complicated optical phenomena and their highly sensitive optoelectrical properties to experimental variations, TQLEDs cannot be optimized easily for practical use. This review summarizes previous studies that have investigated top‐emitting device structures and discusses ways to advance the performance of TQLEDs. First, theories relevant to the optoelectrical properties of TQLEDs are introduced. Second, advancements in device optimization are presented, where the underlying theories for each are considered. Finally, multilateral strategies for TQLEDs to enable their wider application to advanced industries are discussed. This work believes that this review can provide valuable insights for realizing commercial TQLEDs applicable to a broad range of applications.

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High-refractive-index capping layer improves top-light-emitting device performance

Cited by 7 publications

References 42 publications

Technical status of top-emission organic light-emitting diodes

Technical status of top-emission organic light-emitting diodes

Angle‐Independent Top‐Emitting Quantum‐Dot Light‐Emitting Diodes Using a Solution‐Processed Subwavelength Scattering–Capping Layer

Top‐Emitting Quantum Dot Light‐Emitting Diodes: Theory, Optimization, and Application

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