scholarly journals Use of Recycling-Reflection Color-Purity Enhancement Film to Improve Color Purity of Full-Color Micro-LEDs

2022 ◽  
Vol 17 (1) ◽  
Author(s):  
Zhi Ting Ye ◽  
Jun-Yi Wu
Keyword(s):  
Conversion Efficiency ◽  
High Efficiency ◽  
Color Purity ◽  
Incident Wavelength ◽  
Excitation Light ◽  
Full Color ◽  
Conversion Materials ◽  
Pass Through ◽  
Color Conversion ◽  
Light Conversion Efficiency

Abstract A common full-color method involves combining micro-light-emitting diodes (LEDs) chips with color conversion materials such as quantum dots (QDs) to achieve full color. However, during color conversion between micro-LEDs and QDs, QDs cannot completely absorb incident wavelengths cause the emission wavelengths that including incident wavelengths and converted wavelength through QDs, which compromises color purity. The present paper proposes the use of a recycling-reflection color-purity-enhancement film (RCPEF) to reflect the incident wavelength multiple times and, consequently, prevent wavelength mixing after QDs conversion. This RCPEF only allows the light of a specific wavelength to pass through it, exciting blue light is reflected back to the red and green QDs layer. The prototype experiment indicated that with an excitation light source wavelength of 445.5 nm, the use of green QDs and RCPEFs increased color purity from 77.2% to 97.49% and light conversion efficiency by 1.97 times and the use of red QDs and RCPEFs increased color purity to 94.68% and light conversion efficiency by 1.46 times. Thus, high efficiency and color purity were achieved for micro-LEDs displays. Graphical Abstract

scholarly journals Improved Color Purity of Monolithic Full Color Micro-LEDs Using Distributed Bragg Reflector and Blue Light Absorption Material

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 436 ◽  
Author(s):  
Shao-Yu Chu ◽  
Hung-Yu Wang ◽  
Ching-Ting Lee ◽  
Hsin-Ying Lee ◽  
Kai-Ling Laing ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Absorption ◽  
Bragg Reflector ◽  
Color Purity ◽  
Distributed Bragg Reflector ◽  
Light Emitting ◽  
Full Color ◽  
Conversion Materials ◽  
Bottom Side ◽  
Color Conversion

In this study, CdSe/ZnS core-shell quantum dots (QDs) with various dimensions were used as the color conversion materials. QDs with dimensions of 3 nm and 5 nm were excited by gallium nitride (GaN)-based blue micro-light-emitting diodes (micro-LEDs) with a size of 30 μm × 30 μm to respectively form the green and red lights. The hybrid Bragg reflector (HBR) with high reflectivity at the regions of the blue, green, and red lights was fabricated on the bottom side of the micro-LEDs to reflect the downward light. This could enhance the intensity of the green and red lights for the green and red QDs/micro-LEDs to 11% and 10%. The distributed Bragg reflector (DBR) was fabricated on the QDs color conversion layers to reflect the non-absorbed blue light that was not absorbed by the QDs, which could increase the probability of the QDs excited by the reflected blue light. The blue light absorption material was deposited on the DBR to absorb the blue light that escaped from the DBR, which could enhance the color purity of the resulting green and red QDs/micro-LEDs to 90.9% and 90.3%, respectively.

scholarly journals High-Performance Color-Converted Full-Color Micro-LED Arrays

2020 ◽  
Vol 10 (6) ◽  
pp. 2112 ◽  
Author(s):  
Won Hee Kim ◽  
Young Jae Jang ◽  
Ja-Yeon Kim ◽  
Myungsoo Han ◽  
MinJae Kang ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
High Performance ◽  
Efficient Technique ◽  
Full Color ◽  
Conversion Materials ◽  
Color Conversion ◽  
Led Arrays ◽  
Lithography Technique

Color-converted micro-LED displays consisting of mono-blue-colored micro LED arrays and color-conversion materials have been used to achieve full color while reliving the transfer and epitaxial growth of three different-colored micro LEDs. An efficient technique is suggested to deposit the color-conversion layers on the blue micro LEDs by using a mixture of photo-curable acrylic and nano-organic color-conversion materials through the conventional lithography technique. This study attempts to provide a solution to fabricate full-color micro-LED displays.

scholarly journals Mini-LED and Micro-LED: Promising Candidates for the Next Generation Display Technology

2018 ◽  
Vol 8 (9) ◽  
pp. 1557 ◽  
Author(s):  
Tingzhu Wu ◽  
Chin-Wei Sher ◽  
Yue Lin ◽  
Chun-Fu Lee ◽  
Shijie Liang ◽  
...  
Keyword(s):  
High Efficiency ◽  
Contrast Ratio ◽  
Consumer Electronics ◽  
Next Generation ◽  
Light Emitting ◽  
Full Color ◽  
Chip Size ◽  
Display Technology ◽  
Main Components ◽  
Color Conversion

Displays based on inorganic light-emitting diodes (LED) are considered as the most promising one among the display technologies for the next-generation. The chip for LED display bears similar features to those currently in use for general lighting, but it size is shrunk to below 200 microns. Thus, the advantages of high efficiency and long life span of conventional LED chips are inherited by miniaturized ones. As the size gets smaller, the resolution enhances, but at the expense of elevating the complexity of fabrication. In this review, we introduce two sorts of inorganic LED displays, namely relatively large and small varieties. The mini-LEDs with chip sizes ranging from 100 to 200 μm have already been commercialized for backlight sources in consumer electronics applications. The realized local diming can greatly improve the contrast ratio at relatively low energy consumptions. The micro-LEDs with chip size less than 100 μm, still remain in the laboratory. The full-color solution, one of the key technologies along with its three main components, red, green, and blue chips, as well color conversion, and optical lens synthesis, are introduced in detail. Moreover, this review provides an account for contemporary technologies as well as a clear view of inorganic and miniaturized LED displays for the display community.

scholarly journals Tripling the Optical Efficiency of Color-Converted Micro-LED Displays with Funnel-Tube Array

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
Fangwang Gou ◽  
En-Lin Hsiang ◽  
Guanjun Tan ◽  
Yi-Fen Lan ◽  
Cheng-Yeh Tsai ◽  
...  
Keyword(s):  
Light Intensity ◽  
Epitaxial Growth ◽  
Optical Density ◽  
Contrast Ratio ◽  
Optical Efficiency ◽  
Full Color ◽  
Led Array ◽  
Conversion Materials ◽  
Low Efficiency ◽  
Color Conversion

Color-converted micro-LED displays consist of a mono-color micro-LED array and color conversion materials to achieve full color, while relieving the burden of epitaxial growth of three-color micro-LEDs. However, it usually suffers from low efficiency and color crosstalk due to the limited optical density of color conversion materials. With funnel-tube array, the optical efficiency of the color-converted micro-LED display can be improved by ~3X, while the crosstalk is eliminated. After optimization of the tapper angle, the ambient contrast ratio is also improved due to higher light intensity.

scholarly journals 39.1: Invited Paper: Organic Color‐Conversion Materials for Full‐Color MicroLED Displays

2021 ◽  
Vol 52 (S1) ◽  
pp. 269-269
Author(s):  
Shou-Cheng Dong ◽  
Yibin Jiang ◽  
Ching W. Tang
Keyword(s):  
Full Color ◽  
Conversion Materials ◽  
Color Conversion

scholarly journals High-Efficiency Responsive Smart Windows Fabricated by Carbon Nanotubes Modified by Liquid Crystalline Polymers

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 440
Author(s):  
Yuan Deng ◽  
Shi-Qin Li ◽  
Qian Yang ◽  
Zhi-Wang Luo ◽  
He-Lou Xie
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Crystalline ◽  
Near Infrared ◽  
High Efficiency ◽  
Polymer Brush ◽  
Light Transmittance ◽  
Smart Window ◽  
Vertical Orientation ◽  
Smart Windows ◽  
Conversion Materials

Smart windows can dynamically and adaptively adjust the light transmittance in non-energy or low-energy ways to maintain a comfortable ambient temperature, which are conducive to efficient use of energy. This work proposes a liquid crystal (LC) smart window with highly efficient near-infrared (NIR) response using carbon nanotubes grafted by biphenyl LC polymer brush (CNT-PDB) as the orientation layer. The resultant CNT-PDB polymer brush can provide the vertical orientation of LC molecules to maintain the initial transparency. At the same time, the smart window shows a rapid response to NIR light, which can quickly adjust the light transmittance to prevent sunlight from entering the room. Different from common doping systems, this method avoids the problem of poor compatibility between the LC host and photothermal conversion materials, which is beneficial for improving the durability of the device.

scholarly journals High-Efficiency, Dual-Band Beam Splitter Based on an All-Dielectric Quasi-Continuous Metasurface

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3184
Author(s):  
Jing Li ◽  
Yonggang He ◽  
Han Ye ◽  
Tiesheng Wu ◽  
Yumin Liu ◽  
...  
Keyword(s):  
Wavelength Range ◽  
Conversion Efficiency ◽  
Antenna Arrays ◽  
Beam Splitter ◽  
High Efficiency ◽  
Visible Region ◽  
Polarized Light ◽  
Dual Band ◽  
Phase Gradient ◽  
Total Transmission

Metasurface-based beam splitters attracted huge interest for their superior properties compared with conventional ones made of bulk materials. The previously reported designs adopted discrete metasurfaces with the limitation of a discontinuous phase profile. In this paper, we propose a dual-band beam splitter, based on an anisotropic quasi-continuous metasurface, by exploring the optical responses under x-polarized (with an electric field parallel to the direction of the phase gradient) and y-polarized incidences. The adopted metasurface consists of two identical trapezoidal silicon antenna arrays with opposite spatial variations that lead to opposite phase gradients. The operational window of the proposed beam splitter falls in the infrared and visible region, respectively, for x- and y-polarized light, resulting from the different mechanisms. When x-polarized light is incident, the conversion efficiency and total transmission of the beam splitter remains higher than 90% and 0.74 within the wavelength range from 969 nm to 1054 nm, respectively. In this condition, each array can act as a beam splitter of unequal power. For y-polarized incidence, the maximum conversion efficiency and transmission reach approximately 100% and 0.85, while the values remain higher than 90% and 0.65 in the wavelength range from 687 nm to 710 nm, respectively. In this case, each array can be viewed as an effective beam deflector. We anticipate that it can play a key role in future integrated optical devices.

scholarly journals The effect of nanoparticulate PdO co-catalysts on the faradaic and light conversion efficiency of WO3 photoanodes for water oxidation

2021 ◽  
Author(s):  
Anna A. Wilson ◽  
Sacha Corby ◽  
Laia Francàs ◽  
James R. Durrant ◽  
Andreas Kafizas
Keyword(s):  
Conversion Efficiency ◽  
Water Oxidation ◽  
Faradaic Efficiency ◽  
Co Catalysts ◽  
Photocurrent Generation ◽  
Light Conversion Efficiency ◽  
Electron Extraction

PdO nanoparticles grown on the surface of nanostructured WO3 photoanodes dramatically increase the faradaic efficiency of water oxidation from 52% to 92%, whilst also enhancing photocurrent generation and electron extraction rates.

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