scholarly journals Band-Engineered Structural Design of High-Performance Deep-Ultraviolet Light-Emitting Diodes

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 271
Author(s):  
Jih-Yuan Chang ◽  
Man-Fang Huang ◽  
Chih-Yung Huang ◽  
Shih-Chin Lin ◽  
Ching-Chiun Wang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Structural Design ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Fine Tuning ◽  
Algan Layer ◽  
Electron Blocking Layer ◽  
Light Emitting ◽  
Peak Emission Wavelength ◽  
Deep Ultraviolet

In this study, systematic structural design was investigated numerically to probe into the cross-relating influences of n-AlGaN layer, quantum barrier (QB), and electron-blocking layer (EBL) on the output performance of AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs) with various Al compositions in quantum wells. Simulation results show that high-Al-composition QB and high-Al-composition EBL utilized separately are beneficial for the enhancement of carrier confinement, while the wall-plug efficiency (WPE) degrades dramatically if both high-Al-composition QB and EBL are existing in a DUV LED structure simultaneously. DUV LEDs may be of great optical performance with appropriate structural design by fine-tuning the material parameters in n-AlGaN layer, QB, and EBL. The design curves provided in this paper can be very useful for the researchers in developing the DUV LEDs with a peak emission wavelength ranging from 255 nm to 285 nm.

Control of Barrier Width in Perovskite Multiple Quantum Wells for High Performance Green Light–Emitting Diodes

2018 ◽  
Vol 7 (3) ◽  
pp. 1801575 ◽  
Author(s):  
Maotao Yu ◽  
Chang Yi ◽  
Nana Wang ◽  
Liangdong Zhang ◽  
Renmeng Zou ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Barrier Width ◽  
Light Emitting

Enhanced electrical performance by modulation-doping in AlGaN-based deep ultraviolet light-emitting diodes

2019 ◽  
Vol 33 (08) ◽  
pp. 1950088
Author(s):  
Sipan Yang ◽  
Miao He ◽  
Jianchang Yan ◽  
Kunhua Wen ◽  
Junxi Wang ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Light Emission ◽  
Electrical Performance ◽  
Algan Layer ◽  
Modulation Doping ◽  
Light Emitting ◽  
Growth Method ◽  
Deep Ultraviolet ◽  
Ultraviolet Light Emitting Diodes

Through the silicon modulation-doping (MD) growth method, the electrical performance of AlGaN-based deep ultraviolet light-emitting diodes (DUV-LEDs) is improved by replacing the commonly uniform-doped (UD) method of n-AlGaN layer. The electroluminescence characterisic measurements demonstrate the MD growth method could effectively enhance the light emission intensity. Both the forward voltage and reverse leakage current of the MD samples are obviously reduced compared to those of the UD sample. Due to the existence of periodic Si-MD superlattices in n-AlGaN layers, which may behave like a series of capacitors, the built-in electric fields are formed. Both the measured capacitance–voltage (C–V) characteristics, and related photoluminescence (PL) intensity with the Si-MD growth method are enhanced. In detail, the effects of these capacitors can enhance the peak internal capacitance up to 370 pF in the MD sample, whereas the UD sample is only 180 pF. The results also mean that with better current spreading ability in the MD sample, the MD processes can effectively enhance the efficiency and reliability of DUV-LEDs. Thus, the investigations of the Si-MD growth methods may be useful for improving the electrical performance of DUV-LEDs in future works. Meanwhile, this investigation may partly suggest the minor crystalline quality improvements in the epi-layers succeeding the MD n-AlGaN layer.

scholarly journals Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth

2019 ◽  
Author(s):  
Baiquan Liu ◽  
Yemliha Altintas ◽  
Lin Wang ◽  
Sushant Shendre ◽  
Manoj Sharma ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Shell Growth ◽  
Light Emitting ◽  
Hot Injection ◽  
Key Factor

<p> Colloidal quantum wells (CQWs) are regarded as a new, highly promising class of optoelectronic materials thanks to their unique excitonic characteristics of high extinction coefficient and ultranarrow emission bandwidth. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind compared with other types of LEDs (e.g., organic LEDs, colloidal quantum-dot LEDs, and perovskite LEDs). Herein, for the first time, the authors show high-efficiency CQW-LEDs reaching close to the theoretical limit. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition- and device- engineering, the CQW-LEDs using CdSe/Cd<sub>0.25</sub>Zn<sub>0.75</sub>S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23,490 cd m<sup>-2</sup>, extremely saturated red color with the Commission Internationale de L’Eclairage coordinates of (0.715, 0.283) and stable emission are obtained. The findings indicate that HIS grown CQWs enable high-performance solution-processed LEDs, which may pave the path for CQW-based display and lighting technologies.</p>

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