Effect of various microlens parameters on enhancement of light outcoupling efficiency of organic light emitting diode

Sharma, Rahul K; Katiyar, Monica

doi:10.1016/j.orgel.2016.08.010

Cited by 16 publications

(8 citation statements)

References 59 publications

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“…The reason for the enhanced color conversion ability is shown in Figure f. There are two blue lights that are absorbed by QDs in ML/QD film: (1) incident blue light, refracted at the bottom surface of the ML/QD film; and (2) blue light reflected at the surface of the microlens array because of the total internal reflection . Methacrylate-phenyl siloxane hybrid material has a high refractive index ( n = 1.55) compared to that of air ( n = 1), so the blue light incident to the microlens array with an incident angle greater than 40.2° (sin –1 (1/1.55)) is reflected and can be absorbed by the QDs.…”

Section: Results and Discussionmentioning

confidence: 99%

Long-Term Stable Microlens Array-Integrated Quantum Dot/Siloxane Film for Thin White Backlight Units

Kim

Lee

Kang

et al. 2020

ACS Appl. Nano Mater.

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Reducing the thickness of quantum-dot-incorporated backlight units (QD-BLUs) is an important issue for QD-incorporated display because of various optical sheets and additional barrier films. However, critical challenges such as the aggregation and vulnerability of QDs and the need for a binder for patterning have emerged. Here, we propose a thermally stable and PL-improved microlens/QD-siloxane film (ML/QD film) by UV imprinting of a microlens array on the film surface. Compared to the neat and diffuser/QD films, the thickness of the ML/QD film decreased by 25% to realize white PL, resulting in less QD usage. The ML/QD film showed superior, long-term thermal and moisture stability and a wide color gamut (109% related to NTSC). A glass-fabric reinforced siloxane hybrid (GFRH) film with a high haze value of 92% was fabricated by the refractive index contrast of methacrylate oligo-siloxane resin with glass-fabric. Hazy GFRH (H-GFRH) exhibited a uniform diffusion of light (diffuser sheet) as well as outstanding thermomechanical properties (polymer substrate). The synergetic advantages of the ML/QD film on H-GFRH substrate will be beneficial for the large-scale and thin white QD-BLUs in display applications.

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Section: Results and Discussionmentioning

confidence: 99%

Long-Term Stable Microlens Array-Integrated Quantum Dot/Siloxane Film for Thin White Backlight Units

Kim

Lee

Kang

et al. 2020

ACS Appl. Nano Mater.

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“…On the other hand, external outcoupling structures do not deteriorate the electrical functions of devices and can be readily introduced to the backside of substrate as a form of films. For external outcoupling, corrugated device structures [15,17], microlens array films [18][19][20][21][22][23], and micro-sphere scattering layers [16,24] have been extensively used. However, these external outcoupling structures typically need complex and expensive lithography process to form micro-shape patterns.…”

Section: Introductionmentioning

confidence: 99%

Enhanced outcoupling in down-conversion white organic light-emitting diodes using imprinted microlens array films with breath figure patterns

Han

Joo

Lee

et al. 2019

Science and Technology of Advanced Materials

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We demonstrate high-performance down-conversion microlens array (DC-MLA) films for white organic light-emitting diodes (OLEDs). The DC-MLA films are readily fabricated by an imprinting method based on breath figure patterns, which are directly formed on the polymer substrate with a novel concept. The DC-MLA films result in high-quality white light as well as enhanced light outcoupling efficiency for white OLEDs. The external quantum efficiency and power efficiency of OLEDs with DC-MLA films are increased by a factor of 1.35 and 1.86, respectively, compared to OLEDs without outcoupling films. Moreover, the white OLEDs with DC-MLA films achieve a high color-rendering index of 84.3. It is anticipated that the novel DC-MLA films fabricated by the simple imprinting process with breath figure patterns can contribute to the development of efficient white OLEDs.

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“…For this reason, external and internal light‐extraction layer techniques have been widely studied, such as Bragg's diffraction gratings, periodic corrugation, random patterned structures, microlens array (MLA), low‐index grids, photonic crystals, microcavity (MC) effect, and surface plasmons . For bottom emission OLEDs, the external light‐extraction layer is used, without major limitations, to reduce the loss of light caused in the substrate mode.…”

Section: Introductionmentioning

confidence: 99%

Internal Light‐Extraction Layers with Different Refractive Indices for Organic Light‐Emitting Diodes

Park

et al. 2019

Physica Status Solidi (a)

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High‐performance organic light‐emitting diodes (OLEDs) require a light‐extraction layer either inside or outside the device. Herein, transparent metal oxides (MOs) of various refractive indices are inserted between the anode and glass as internal light‐extraction layers to improve the efficiency of the OLED device. Optical simulations are performed to reveal the optimal thicknesses for the light‐extraction layer of metal oxides of various refractive indices. Light‐extraction layers of metal oxides with optimized thickness are then used in OLED devices to evaluate the performance of devices. The device with the higher refractive index MO light‐extraction layer tends to show better device performance. Although the internal light‐extraction layer is inserted, the current flow in the device and the color coordinate variation depending on the viewing angle do not change significantly. These results are helpful in the development of optimized internal light‐extraction layers for individual colors and in the development of OLED displays with optimized light‐extraction layers for each pixel.

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Effect of various microlens parameters on enhancement of light outcoupling efficiency of organic light emitting diode

Cited by 16 publications

References 59 publications

Long-Term Stable Microlens Array-Integrated Quantum Dot/Siloxane Film for Thin White Backlight Units

Long-Term Stable Microlens Array-Integrated Quantum Dot/Siloxane Film for Thin White Backlight Units

Enhanced outcoupling in down-conversion white organic light-emitting diodes using imprinted microlens array films with breath figure patterns

Internal Light‐Extraction Layers with Different Refractive Indices for Organic Light‐Emitting Diodes

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