scholarly journals Study on the Effect of Size on InGaN Red Micro-LEDs

2021 ◽  
Author(s):  
Ray-Hua Horng ◽  
Chun-Xin Ye ◽  
Po-Wei Chen ◽  
Daisuke Iida ◽  
Kazuhiro Ohkawa ◽  
...  
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Light Emitting Diode ◽  
Blue Shift ◽  
Injection Current ◽  
Emission Wavelength ◽  
Direct Writing ◽  
Light Emitting ◽  
Full Color ◽  
Injection Current Density

Abstract In this research, five sizes (100⊆100, 75⊆75, 50⊆50, 25⊆25, 10⊆10 µm2) of InGaN red micro-light emitting diode (LED) dies are produced using laser-based direct writing and maskless technology. It is observed that with increasing injection current, the smaller the size of the micro-LED, the more obvious the blue shift of the emission wavelength. When the injection current is increased from 0.1 to 1 mA, the emission wavelength of the 10×10 µm2 micro-LED is shifted from 617.15 to 576.87 nm. The obvious blue shift is attributed to the stress release and high current density injection. Moreover, the output power density is very similar for smaller chip micro-LEDs at the same injection current density. This behavior is different from AlGaInP micro-LEDs. The sidewall defect is more easily repaired by passivation, which is similar to the behavior of blue micro-LEDs. The results indicate that the red InGaN epilayer structure provides an opportunity to realize the full color LEDs fabricated by GaN-based LEDs.

High efficiency Green Organic Light-emitting Diode Without Roll-off Under High Current Density

2015 ◽  
Vol 36 (11) ◽  
pp. 1307-1310
Author(s):  
田苗苗 TIAN Miao-miao ◽  
贺小光 HE Xiao-guang ◽  
祁金刚 QI Jin-gang ◽  
王 宁 Wang Ning
Keyword(s):  
Current Density ◽  
High Efficiency ◽  
High Current Density ◽  
Light Emitting Diode ◽  
High Current ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light

scholarly journals Highly flexible, full-color, top-emitting quantum dot light-emitting diode tapes

2013 ◽  
Author(s):  
Xuyong Yang ◽  
Evren Mutlugun ◽  
Yuan Gao ◽  
Yongbiao Zhao ◽  
Swee Tiam Tan ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Full Color

Organic Light Emitting Material Direct Writing by Nanomaterial Enabled Laser Transfer

2009 ◽  
Vol 1179 ◽  
Author(s):  
Seung Hwan Ko ◽  
Heng Pan ◽  
Nipun Misra ◽  
Costas Grigoropoulos
Keyword(s):  
Mass Production ◽  
Laser Energy ◽  
Light Emitting Diode ◽  
Nanoparticle Size ◽  
Temperature Sensitive ◽  
Conductive Heat ◽  
Direct Writing ◽  
Light Emitting ◽  
Laser Transfer ◽  
Organic Light

AbstractOrganic light emitting material direct writing is demonstrated based on nanomaterial enabled laser transfer. Through utilization of proper nanoparticle size and type, and the laser wavelength choice, a single laser pulse could transfer well defined and arbitrarily shaped tris-(8-hydroxyquinoline)Al patterns ranging from several microns to millimeter size. The unique properties of nanomaterials allow laser induced forward transfer at low laser energy (0.05 J/cm2) while maintaining good fluorescence. The technique may be well suited for the mass production of temperature sensitive organic light emitting devices.The combined effects of melting temperature depression, lower conductive heat transfer loss, strong absorption of the incident laser beam, and relatively weak bonding between nanoparticles during laser irradiation result in the transfer of patterns with very sharp edges at relatively lower laser energy than commonly used, thus inducing minimal damage to the target organic light emitting diode material with no evidence of cracks. This technique can be applied to a broad range of laser wavelengths with proper selection of nanoparticle size and size distribution, as well as the material type. Additionally, nanomaterial enabled laser transfer may be particularly advantageous for the mass production of temperature sensitive devices.

scholarly journals The Optical Properties of InGaN/GaN Nanorods Fabricated on (-201) β-Ga2O3 Substrate for Vertical Light Emitting Diodes

Photonics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 42
Author(s):  
Jie Zhao ◽  
Weijiang Li ◽  
Lulu Wang ◽  
Xuecheng Wei ◽  
Junxi Wang ◽  
...  
Keyword(s):  
Stark Effect ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Strain Relaxation ◽  
Blue Shift ◽  
Peak Position ◽  
Excitation Power ◽  
Light Extraction Efficiency ◽  
Excitation Power Density ◽  
Light Emitting

We fabricated InGaN/GaN nanorod light emitting diode (LED) on (-201) β-Ga2O3 substrate via the SiO2 nanosphere lithography and dry-etching techniques. The InGaN/GaN nanorod LED grown on β-Ga2O3 can effectively suppress quantum confined Stark effect (QCSE) compared to planar LED on account of the strain relaxation. With the enhancement of excitation power density, the photoluminescence (PL) peak shows a large blue-shift for the planar LED, while for the nanorod LED, the peak position shift is small. Furthermore, the simulations also show that the light extraction efficiency (LEE) of the nanorod LED is approximately seven times as high as that of the planar LED. Obviously, the InGaN/GaN/β-Ga2O3 nanorod LED is conducive to improving the optical performance relative to planar LED, and the present work may lay the groundwork for future development of the GaN-based vertical light emitting diodes (VLEDs) on β-Ga2O3 substrate.

25.1: Invited Paper: Quantum dots based full-color display on micro-light-emitting-diode technology

2018 ◽  
Vol 49 ◽  
pp. 267-270 ◽  
Author(s):  
CHIH-HAO LIN ◽  
CHUN-FU LEE ◽  
CHIEN-CHUNG LIN ◽  
CHEN-HSIEN CHU ◽  
CHIN-WEI SHER ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Color Display ◽  
Full Color

Optimization for white organic light-emitting diode based on DCJTB as color conversion layer

2018 ◽  
Vol 32 (27) ◽  
pp. 1850299
Author(s):  
Pei Wang ◽  
Zhen Wang ◽  
Ai Chen ◽  
Jia-Feng Xie ◽  
Xin Zheng
Keyword(s):  
Current Efficiency ◽  
Current Density ◽  
White Light ◽  
Power Efficiency ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
High Efficient ◽  
Color Conversion

In this paper, combining phosphorescence and fluorescence to form white light was realized based on DCJTB:PMMA/ITO/NPB/TCTA/FIrpic:TCTA/TPBi/Ir(ppy)3:TPBi/TPBi/Cs2CO3/Al. The effects of red fluorescence on this white light device was studied by adjusting the concentration of DCJTB. The study shows that the device with a DCJTB concentration of 0.7% in the color conversion layer (CCL) generates a peak current efficiency and power efficiency of 23.4 cd ⋅ A[Formula: see text] and 7.5 lm ⋅ W[Formula: see text], respectively. And it is closest to the equal-energy white point of (0.33, 0.33) which shows a CIE (Commission Internationale de L’Eclairage) coordinate of (0.35, 0.43) and a color rendering index (CRI) of 70 at current density of 10 mA ⋅ cm[Formula: see text]. In order to improve the efficiency, we design and fabricate both high efficient and pure white organic light-emitting diode (WOLED) by replacing the single blue emission layer (EML) with double EMLs of FIrpic:TCTA and FIrpic:TPBi. The further study shows that, when the layers of EML is three and the concentration of DCJTB at 0.7%, the device exhibits good performance specifically, at current density of 10 mA ⋅ cm[Formula: see text], the current efficiency of 28.2 cd ⋅ A[Formula: see text] (power efficiency of 10.3 lm ⋅ W[Formula: see text]), and the CIE coordinate of (0.33, 0.31) (CRI of 80.38).

scholarly journals Operando direct observation of spin-states and charge-trappings of blue light-emitting-diode materials in thin-film devices

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fumiya Osawa ◽  
Kazuhiro Marumoto
Keyword(s):  
Blue Light ◽  
High Performance ◽  
Density Functional ◽  
Light Emitting Diode ◽  
Green Light ◽  
Spin States ◽  
Light Emitting ◽  
Full Color ◽  
Color Displays ◽  
Materials Used

Abstract Spin-states and charge-trappings in blue organic light-emitting diodes (OLEDs) are important issues for developing high-device-performance application such as full-color displays and white illumination. However, they have not yet been completely clarified because of the lack of a study from a microscopic viewpoint. Here, we report operando electron spin resonance (ESR) spectroscopy to investigate the spin-states and charge-trappings in organic semiconductor materials used for blue OLEDs such as a blue light-emitting material 1-bis(2-naphthyl)anthracene (ADN) using metal–insulator–semiconductor (MIS) diodes, hole or electron only devices, and blue OLEDs from the microscopic viewpoint. We have clarified spin-states of electrically accumulated holes and electrons and their charge-trappings in the MIS diodes at the molecular level by directly observing their electrically-induced ESR signals; the spin-states are well reproduced by density functional theory. In contrast to a green light-emitting material, the ADN radical anions largely accumulate in the film, which will cause the large degradation of the molecule and devices. The result will give deeper understanding of blue OLEDs and be useful for developing high-performance and durable devices.

Tunable, full-color nanowire light emitting diode arrays monolithically integrated on Si and sapphire

2016 ◽  
Author(s):  
Renjie Wang ◽  
Yong-Ho Ra ◽  
Yuanpeng Wu ◽  
Songrui Zhao ◽  
Hieu P. T. Nguyen ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Light Emitting ◽  
Monolithically Integrated ◽  
Full Color
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