High Efficiency Bulk Crystalline Silicon Light Emitting Diodes

2002 ◽  
Vol 744 ◽  
Author(s):  
Jianhua Zhao ◽  
Aihua Wang ◽  
Thorsten Trupke ◽  
Martin A. Green
Keyword(s):  
Power Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
Light Emission ◽  
Crystalline Silicon ◽  
Collection Efficiency ◽  
Light Emitting Diode ◽  
Coupled System ◽  
High Power Conversion Efficiency ◽  
Light Emitting

ABSTRACTA high power conversion efficiency above 1% from a bulk crystalline silicon (c-Si) light-emitting diode (LED) has been demonstrated at near room temperature. These devices are based on normally weak one- and two-phonon assisted sub-bandgap light emission processes. Their improved performance results from device designs that take advantage of enhanced light absorption by a light trapping scheme which was developed for high efficiency silicon solar cells, and from reducing scope for parasitic non-radiative recombination within the diode. Each feature individually is shown to improve efficiency by a factor of ten, accounting for an improvement by factor of one hundred compared to baseline devices.Also demonstrated is a greatly improved band-edge light emission and detection using bulk c-Si diodes. A bulk c-Si LED is combined with a similar diode used as a detector that collects the light emitted with a high quantum collection efficiency of 33%, to produce a silicon to silicon optically coupled system that demonstrates 0.18% coupling quantum efficiency. The crystalline silicon LED demonstrates similarly high performance at very low power levels, where it has even higher power efficiency than a high efficiency GaAlAs LED.

High-Performance Red Phosphorescent Organic Light-Emitting Diodes Based on a Gradient-Doped Emitting Layer

2020 ◽  
Vol 976 ◽  
pp. 110-115
Author(s):  
Fei Yang Liu ◽  
Bin Wei ◽  
Guo Chen
Keyword(s):  
Power Efficiency ◽  
High Performance ◽  
Doping Concentration ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Control Device ◽  
Organic Light Emitting Diodes ◽  
Electron Recombination ◽  
Light Emitting ◽  
Organic Light

Recently the phosphorescent organic light-emitting diodes (PhOLEDs) have attracted tremendous attention owing to their extremely high performance. However, PhOLEDs always suffer from the annihilation and quenching of excitons due to higher guest doping concentration. In this work, to obtain a high efficiency red PhOLED, a gradient-doped emitting layer (EML) was employed in the device to improve the device efficiency and suppress the annihilation of excitons. A significant enhancement in terms of current efficiency (CE) and power efficiency (PE) of PhOLEDs with optimized gradient-doped EML was realized with the maximum CE of 13.84 cd A-1 and PE of 18.11 lm W−1, which are 33.9% and 60.7% higher than that of the control device, respectively. The enhanced performance of the PhOLEDs is attributed to the lower guest doping concentration in gradient-doped EML and balanced hole/electron recombination, leading to the reduced triplet-triplet annihilation and triplet-polaron quenching. The simple strategy opens a new avenue for fabricating high-performance PhOLEDs.

Eu3+/Eu2+/Tb3+ co-activated single-phase Gd2O2S: A high-performance white light emitting phosphor for light emitting diode

2021 ◽  
Vol 11 (1) ◽  
pp. 54-62
Author(s):  
Jinpeng Xie ◽  
Bonan Liu ◽  
Qingtao Qong ◽  
Zhicheng Xu ◽  
Zhiqiang Jin ◽  
...  
Keyword(s):  
White Light ◽  
High Performance ◽  
Single Phase ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Energy Transfer Mechanism ◽  
Excitation Spectra ◽  
Phosphor Material ◽  
Light Emitting ◽  
Co Doped

In this work, we report Eu3+/Tb3+/Eu2+ co-activated Gd2O2 S as novel phosphor materials that can be effectively applied in the white-light emitting diode based on a near-UV chip with sensational performances. The luminescent properties and energy transfer mechanism have been thoroughly investigated. The as-prepared europium/terbium co-doped Gd2O2 S phosphors exhibit strong fluorescence with tunable color output under UV-vis light excitation. Furthermore, a high response to ultraviolet illumination of 398 nm wavelength was observed in the excitation spectra, indicating an excellent match with a light-emitting-diode chip in the dominant emissions. It is found that a tricolor (blue, green and red) emission band which results in a white light emission can be acquired when Eu3+, Eu2+ and Tb3+ ions are all co-doped into the single phase Gd2O2S, and an optimum ion doping level (10 at.% Eu and 0.7 at.% Tb) can effectively emit nearly pure white color photoluminescence with lifetime effectively tuned from 0.55 ms to 1.10 ms. The CIE (Commission International de I'Eclairage 1931 chromaticity) is X = 0.3507, Y = 0.3029. It is therefore expected that the newly found phosphor material with high-performance properties possess great potentials for the future advanced white LED applications.

scholarly journals High Efficiency Driver for AMOLED with Compensation

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Said Saad ◽  
Lotfi Hassine
Keyword(s):  
High Efficiency ◽  
Crystalline Silicon ◽  
Light Emitting Diode ◽  
Flat Panel Display ◽  
Silicon Thin Film ◽  
Active Matrix ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
Driver Circuit

A new proposed compensation driver circuit of flat-panel display (FPD) based on organic light emitting diodes (OLEDs) and on poly-crystalline silicon thin-film transistors (poly-Si TFTs) is presented. This driver circuit is developed for an active-matrix organic light-emitting-diode (AMOLED) display and its efficiency is verified compared with the conventional configuration with 2 TFTs. According to results, this circuit is suitable to achieve acceptable level for power consumption, high contrast, maximum gray levels, and better brightness. And, to show this, a stable driving scheme is developed for circuit with much compensation such as against the data degradation, the threshold voltage dispersions of TFT drive, and suppression of TFT leakage current effect.

scholarly journals Modeling and Simulations of 4H-SiC/6H-SiC/4H-SiC Single Quantum-Well Light Emitting Diode Using Diffusion Bonding Technique

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1499
Author(s):  
Muhammad Haroon Rashid ◽  
Ants Koel ◽  
Toomas Rang ◽  
Nadeem Nasir ◽  
Haris Mehmood ◽  
...  
Keyword(s):  
Quantum Well ◽  
Power Efficiency ◽  
Semiconductor Device ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Design Parameters ◽  
Diffusion Welding ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Light Emitting

In the last decade, Silicon carbide (SiC) has emerged as a potential material for high-frequency electronics and optoelectronics applications that may require elevated temperature processing. SiC exists in more than 200 different crystallographic forms, referred to as polytypes. Based on their remarkable physical and electrical characteristics, such as better thermal and electrical conductivities, 3C-SiC, 4H-SiC, and 6H-SiC are considered as the most distinguished polytypes of SiC. In this article, physical device simulation of a light-emitting diode (LED) based on the unique structural configuration of 4H-SiC and 6H-SiC layers has been performed which corresponds to a novel material joining technique, called diffusion welding/bonding. The proposed single quantum well (SQW) edge-emitting SiC-based LED has been simulated using a commercially available semiconductor device simulator, SILVACO TCAD. Moreover, by varying different design parameters, the current-voltage characteristics, luminous power, and power spectral density have been calculated. Our proposed LED device exhibited promising results in terms of luminous power efficiency and external quantum efficiency (EQE). The device numerically achieved a luminous efficiency of 25% and EQE of 16.43%, which is at par performance for a SQW LED. The resultant LED structure can be customized by choosing appropriate materials of varying bandgaps to extract the light emission spectrum in the desired wavelength range. It is anticipated that the physical fabrication of our proposed LED by direct bonding of SiC-SiC wafers will pave the way for the future development of efficient and cost-effective SiC-based LEDs.

scholarly journals Phosphorescent Molecularly Doped Light-Emitting Diodes with Blended Polymer Host and Wide Emission Spectra

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jun Wang ◽  
Jun Gou ◽  
Weizhi Li
Keyword(s):  
Power Efficiency ◽  
High Efficiency ◽  
Light Emission ◽  
Green Light ◽  
Emission Spectra ◽  
Iridium Complex ◽  
Light Emitting ◽  
Host Materials ◽  
Green Light Emission ◽  
Organic Devices

Stable green light emission and high efficiency organic devices with three polymer layers were fabricated using bis[2-(4′-tert-butylphenyl)-1-phenyl-1H-benzoimidazole-N,C2′] iridium(III) (acetylacetonate) doped in blended host materials. The 1 wt% doping concentration showed maximum luminance of 7841 cd/cm2at 25.6 V and maximum current efficiency of 9.95 cd/A at 17.2 V. The electroluminescence spectra of devices indicated two main peaks at 522 nm and 554 nm coming from phosphor dye and a full width at half maximum (FWHM) of 116 nm. The characteristics of using blended host, doping iridium complex, emission spectrum, and power efficiency of organic devices were investigated.

n-Type Diamond Growth by Phosphorus Doping

2007 ◽  
Vol 1039 ◽  
Author(s):  
Hiromitsu Kato ◽  
Toshiharu Makino ◽  
Satoshi Yamasaki ◽  
Hideyo Okushi
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Light Emission ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Diamond Growth ◽  
Phosphorus Doping ◽  
Light Emitting ◽  
Compensation Ratio ◽  
Phosphorus Doped

AbstractPhosphorus doping on (001)-oriented diamond is introduced and compared with results achieved on (111) diamond. Detailed procedures, conditions, doping characteristics, and recent electrical properties of (001) phosphorus-doped diamond films are described. Now the highest mobility is reached to be ∼780 cm2/Vs at room temperature. The carrier compensation ratio, which is still high around 50-80 %, is the most important issues for (001) phosphorus-doped diamond to improve its electrical property. The origin of compensators in phosphorus-doped diamond is investigated, while yet to be identified.Ultraviolet light emitting diode with p-i-n junction structure is also introduced using (001) n-type diamond. A strong UV light emission at around ∼240 nm is observed even at room temperature. High performance of diamond UV-LED is demonstrated.

Integrated Heterostructure Devices (IHDS): A New Approach for the Fabrication of High-Efficiency Blue/Green Light Emitters Based on II-VI Materials

1992 ◽  
Vol 281 ◽  
Author(s):  
Y. Lansari ◽  
Z. Yu ◽  
J. Ren ◽  
C. Boney ◽  
J. W. Cook ◽  
...  
Keyword(s):  
Band Gap ◽  
High Efficiency ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Green Light ◽  
Wide Band ◽  
Light Emitters ◽  
Light Emitting ◽  
Type Layer ◽  
Heterostructure Devices

ABSTRACTIntegrated heterostructure devices (IHDs) comprised of II-VI materials in multi-layered structures for light emitting diode (LED) and laser diode (LD) applications are described. These IHDs combine a light emission multilayer structure (wide band gap II-VI layers) with an abrupt or graded heterostructure (comprised of narrow band gap II-VI layers) for improved ohmic contact to the upper p-type layer of the light emitting structure.

scholarly journals Thermally Activated Delayed Fluorescence in Commercially Available Materials for Solution-Process Exciplex OLEDs

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1668
Author(s):  
Zong-Liang Tseng ◽  
Wei-Lun Huang ◽  
Tzu-Hung Yeh ◽  
You-Xun Xu ◽  
Chih-Hsun Chiang
Keyword(s):  
High Performance ◽  
Lower Cost ◽  
High Efficiency ◽  
Collection Efficiency ◽  
Solution Process ◽  
Delayed Fluorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Simple Combination

Organic light-emitting diodes (OLEDs) have developed rapidly in recent years. Thermally activated delayed fluorescent (TADF) molecules open a path to increase exciton collection efficiency from 25% to 100%, and the solution process provides an alternative technology to achieve lower cost OLEDs more easily. To develop commercial materials as exciplex hosts for high-performance and solution-processed OLEDs, we attempted to use 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine (TAPC), poly(9-vinylcarbazole) (PVK), N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), and poly(N,N'-bis-4-butylphenyl-N,N'-bisphenyl)benzidine (Poly-TPD) as the donors and 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (POT2T) as the acceptor to obtain the TADF effect. All donors and the acceptor were purchased from chemical suppliers. Our work shows that excellent TADF properties and high-efficiency exciplex OLEDs with low turn-on voltage and high luminance can be achieved with a simple combination of commercial materials.

scholarly journals Adjusting White OLEDs with Yellow Light Emission Phosphor Dye and Ultrathin NPB Layer Structure

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jun Wang ◽  
Weizhi Li
Keyword(s):  
Thin Layer ◽  
White Light ◽  
Power Efficiency ◽  
High Efficiency ◽  
Light Emission ◽  
Layer Structure ◽  
Emission Spectra ◽  
Device Structure ◽  
Phosphor Material ◽  
Light Emitting

High efficiency white organic light emission devices were demonstrated with phosphor material dye bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2′]iridium (acetylacetonate) and ultrathin layer structure. The ultra thin layer be composed of 4,4′-bis[N-1-naphthyl-N-phenyl-amino]biphenyl (NPB) or 4,4′-N,N′-dicarbazole-biphenyl : NPB mixed layer with blue light emission. The emission spectra of devices could be adjusted by different phosphor doping concentrations and ultra thin layer structure. Warm white light emitting device could be obtained with 5 wt% doping concentration and power efficiency of 9.93 lm/W at 5 V. Pure white light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.30) and external quantum efficiency of 4.49% could be achieved with ultra thin layer device structure and 3 wt% phosphor doped device.

A High Efficiency, Purcell-enhanced Microcavity Single Photon Emitting Diode

2009 ◽  
Vol 1208 ◽  
Author(s):  
David J.P. Ellis ◽  
Anthony J. Bennett ◽  
Samuel J. Dewhurst ◽  
Christine A. Nicoll ◽  
David A. Ritchie ◽  
...  
Keyword(s):  
Radiative Decay ◽  
High Efficiency ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Collection Efficiency ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Light Emitting ◽  
Single Quantum Dot ◽  
Low Refractive Index

AbstractEfficient, high-frequency quantum light sources are a prerequisite for advanced quantum information processing. Here, we report the observation of a Purcell enhancement in the radiative decay rate of a single quantum dot, embedded in a microcavity light-emitting diode structure. An annulus of low-refractive-index aluminium oxide, formed by wet oxidation, is used to simultaneously achieve lateral confinement of both the optical mode and the current through the device. This technique reduces the active area of the device without impeding the electrical properties of the p-i-n diode. We measure a photon collection efficiency of 14 ± 1% and demonstrate single photon electroluminescence at repetition rates up to 0.5 GHz.

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