scholarly journals Optimization of the Cryogenic Light-Emitting Diodes for High-Performance Broadband Terahertz Upconversion Imaging

2021 ◽  
Vol 9 ◽  
Author(s):  
Peng Bai ◽  
Yueheng Zhang ◽  
Wenzhong Shen ◽  
Ning Yang ◽  
Weidong Chu
Keyword(s):  
High Performance ◽  
Light Emitting Diode ◽  
Internal Quantum Efficiency ◽  
Operation Mode ◽  
Optimization Method ◽  
Light Extraction Efficiency ◽  
Recombination Mechanism ◽  
Imaging Device ◽  
Light Emitting ◽  
Micro Lens

High-performance terahertz (THz) imaging devices have drawn wide attention due to their significant application in a variety of application fields. Recently, the upconversion device based on the integrated homo-junction interfacial workfunction internal photoemission detector and light-emitting diode (HIWIP-LED) has emerged as a promising candidate for broadband THz upconversion pixelless imaging device. In this paper, systematical investigations on the cryogenic-temperature performances of the LED part in HIWIP-LED devices, including electroluminescence (EL) spectra and the EL efficiency, have been carried out by elaborating the radiative recombination mechanism in the quantum well, internal quantum efficiency, and the light extraction efficiency (LEE) both experimentally and theoretically. On this basis, we have further studied the operation mode of the HIWIP-LED and concluded that the LEE could directly determine the upconversion efficiency. A numerical simulation has been performed to optimize the LEE. Numerical results show that the device with a micro-lens geometry structure could significantly improve the LEE of the LED thereby increasing the upconversion efficiency. An optimal upconversion efficiency value of 0.12 W/W and a minimum noise equivalent power (NEP) of 14 pW/Hz1/2 are achieved using the micro-lens structure together with anti-reflection coating. This work gives a precise description of cryogenic LED performance in the HIWIP-LED device and provides an optimization method for the broadband HIWIP-LED THz upconversion pixelless imaging device.

scholarly journals Performance of InGaN/GaN Light Emitting Diodes with n-GaN Layer Embedded with SiO2 Nano-Particles

2018 ◽  
Vol 8 (9) ◽  
pp. 1574 ◽  
Author(s):  
Hong-Seo Yom ◽  
Jin-Kyu Yang ◽  
Alexander Polyakov ◽  
In-Hwan Lee
Keyword(s):  
High Performance ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Light Output ◽  
Front Surface ◽  
Nano Particles ◽  
Light Extraction Efficiency ◽  
Light Emitting ◽  
Dry Etch ◽  
Air Void

We demonstrate high-performance InGaN/GaN blue light emitting diodes (LEDs) embedded with an air-void layer produced by a dry-etch of nano-pillars in an n-GaN layer grown on patterned sapphire substrate (PSS), filling the space between nano-pillars with SiO2 nano-particles (NPs) and subsequent epitaxial overgrowth. The structure exhibits enhanced output power compared to similarly grown reference conventional LED without the air-void layer. This change in growth procedure contributes to the increase of internal quantum efficiency (IQE) and light extraction efficiency (LEE) resulting in a 13.5% increase of light output. LEE is 2 times more affected than IQE in the modified structure. Simulation demonstrates that the main effect causing the LEE changes is due to the emitted light being confined within the upper space above the air-void layer and thus enhancing the light scattering by the SiO2 NPs and preferential light via front surface.

Electrically driven single microribbon based near-infrared exciton-polariton light-emitting diode

CrystEngComm ◽  
2021 ◽  
Author(s):  
Mingming Jiang ◽  
Fupeng Zhang ◽  
Kai Tang ◽  
Peng Wan ◽  
Caixia Kan
Keyword(s):  
High Performance ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Coherent Light ◽  
Light Emitting ◽  
Exciton Polaritons ◽  
Laser Devices

Achieving electrically-driven exciton-polaritons has drawn substantial attention toward developing ultralow-threshold coherent light sources, containing polariton laser devices and high-performance light-emitting diodes (LEDs). In this work, we demonstrate an electrically driven...

Ultraviolet light-emitting diode-assisted highly sensitive room temperature NO2 gas sensor for low-temperature solution-processed ZnO/TiO2 nanorods decorated with plasmonic Au nanoparticles

Nanoscale ◽  
2021 ◽  
Author(s):  
Soon-Hwan Kwon ◽  
Tae-Hyeon Kim ◽  
Sang-Min Kim ◽  
Semi Oh ◽  
Kyoung-Kook Kim
Keyword(s):  
Gas Sensors ◽  
High Performance ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
No2 Gas Sensor ◽  
Highly Sensitive ◽  
Temperature Solution ◽  
Semiconducting Metal Oxides

Nanostructured semiconducting metal oxides such as SnO2, ZnO, TiO2, and CuO have been widely used to fabricate high performance gas sensors. To improve the sensitivity and stability of gas sensors,...

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.

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.

Reactivity of bilirubin photoisomers on the measurement of direct bilirubin using vanadic acid method

2017 ◽  
Vol 55 (2) ◽  
pp. 296-298
Author(s):  
Hitoshi Okada ◽  
Susumu Itoh ◽  
Shohei Kawamoto ◽  
Miyo Ozaki ◽  
Takashi Kusaka
Keyword(s):  
High Performance ◽  
Light Emitting Diode ◽  
Direct Bilirubin ◽  
Acid Oxidation ◽  
Albumin Solution ◽  
Light Emitting ◽  
Oxidation Method ◽  
Before And After ◽  
Vanadic Acid ◽  
Human Serum Albumin Solution

Objective Investigation of the reactivity of fractions of bilirubin photoisomers with the vanadic acid oxidation method. Methods Bilirubin photoisomers were prepared by irradiating a bilirubin/human serum albumin solution with blue light emitting diode. Direct bilirubin and bilirubin fractions were measured using the vanadic acid oxidation method and high-performance liquid chromatography in the sample before and after irradiation. Results Direct bilirubin was increased in the solution containing bilirubin photoisomers. ( EE)-/( EZ) -cyclobilirubin-IXα and ( ZE)-/( EZ)-bilirubin-IXα completely disappeared after the addition of vanadic acid. Conclusion Bilirubin photoisomers reacted as direct bilirubin in the vanadic acid oxidation method.

Sign in / Sign up

Export Citation Format

Share Document