We propose making light emitting diodes out of inverse spin valves. The proposed diodes rely on the spin-dependent electron transport of inverse spin valves that are layered structures of a ferromagnetic half-metal sandwiched between two non-magnetic metals. Under a bias, a giant spin-dependent chemical potential difference between spin-up and spin-down electrons is created. Thus, the inverse spin valves are possible to emit light when electrons in higher chemical potential go to the lower chemical potential. The advantages of this type of light emitting diodes include tunableness and less demand on materials.
Devices which exploit the quantum properties of materials are widespread, with quantum information processors and quantum sensors showing significant progress. Organic devices offer interesting opportunities for quantum technologies owing to their engineerable spin properties, with spintronic operation and spin resonance magnetic-field sensing demonstrated in research grade devices, as well as proven compatibility with large scale fabrication techniques. Yet several important challenges remain as we move toward scaling these proof-of-principle quantum devices to larger integrated logic systems…
Light-Emitting Diodes with Micrometer-Thick Perovskite Charge Transport Layers
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University（成均馆大学 SKKU 纳米技术高级研究所 (SAINT)）；Department of Physics, Yonsei University（延世大学物理系）
Direct measurement of the magnetic field effects on carrier mobilities and recombination in tri-(8-hydroxyquinoline)-aluminum based light-emitting diodes
Surface plasmonic effects of metallic particles have been known to be an effective method to improve the performance light emitting didoes. In this work, we reported the sputtered Au nanoparticles enhanced electroluminescence in inverted quantum dot light emitting diodes (ITO/Au NPs/ZnMgO/QDs/TFB/PEDOT:PSS/Al). By combining the time-resolved photoluminescence, transient electroluminescence and ultraviolet photoelectron spectrometer measurements, the enhancement can be explained to the internal field enhanced exciton coupling to surface plasmons and the increased electron injection rate with Au…
Direct Measurement of Auger Electrons Emitted from a Semiconductor Light-Emitting Diode under Electrical Injection: Identification of the Dominant Mechanism for Efficiency Droop
Origin of Operating Voltage Increase in InGaN-based Light-emitting Diodes under High Injection: Phase Space Filling Effect on Forward Voltage Characteristics
In this work, performance and characteristics of AlGaN/AlGaN deep-ultraviolet light-emitting diodes (DUV LEDs) with varied number of quantum-well (QW) are investigated numerically. From our simulation, 1-QW structure give the best performance at low injection current. However, at higher injection current, 2-QWs structure give the largest power output due to its higher total radiative recombination rate and internal quantum efficiency (IQE) compared to other structures. The 2-QWs structure also has less serious efficiency droop at high current than 1-QW, which makes it an optimum structure for …
Enhanced high-temperature performance of GaN light-emitting diodes grown on silicon substrates
我们比较了在硅和蓝宝石衬底上生长的市售GAN发光二极管（LED）的光学和电气特性对温度的依赖性。与传统预期相反，生长在硅衬底上的LED（通常称为GaN-on-Si LED）在较高温度下显示出较小的效率下降，即使具有更多的穿透位错。结温的分析表明，尽管与生长在蓝宝石衬底上的LED相比共享相同的外延结构和封装，但GaN on Si LED具有较冷的结。我们还观察到理想因子随着环境温度的增加而降低，这表明理想二极管电流随着温度的增加而增加。应变和温度系数测量的分析表明，与生长在蓝宝石上的LED相比，Si上GaN LED的有源区内的空穴传输效率增加，这导致了较少的温度依赖性效率下降。
Short wavelength ultraviolet (UV-C) light deactivates DNA of any germs, including multiresistive bacteria and viruses like COVID-19. Two-dimensional (2D) material-based UV-C light emitting diodes can potentially be integrated into arbitrary surfaces to allow for shadow-free surface disinfection. In this work, we perform a series of first-principles calculations to identify the core components of ultrathin LEDs based on hexagonal boron nitride (hBN). The electrons and holes are predicted to be confined in multiple quantum wells (MQWs) by combining hBN layers with different stacking orders. Vari…
In this article, we show that the variation of the wavelength of a non-pumped light-emitting diode (LED) is practically linear with temperature, a novel consequence of Varshni's widely accepted empirical expression. This formula models the bandgap variation for most semiconductors from 0K to their high-temperature limits, subject to fitting parameters. Therefore, we suggest an external thermal mechanism that can be used to tune the wavelength of a constant-current biased LED and also to stabilize its wavelength. Furthermore, we demonstrate the approach on published AlN data and show that the f…
Perovskite nanocrystal light-emitting diodes (LEDs) employing architecture comprising a ZnO nanoparticles electron-transport layer and a conjugated polymer hole-transport layer have been fabricated. The obtained LEDs demonstrate a maximum external-quantum-efficiency of 6.04%, luminance of 12998 Cd/m2 and stable electroluminescence at 519 nm. Importantly, such high efficiency and brightness have been achieved by employing solution processed transport layers, formamidinium lead bromide nanocrystals (CH(NH2)2PbBr3 NCs) synthesized at room-temperature and in air without the use of a Schlenk line, …
White organic light-emitting diodes with an ultra-thin premixed emitting layer
提出了一种基于超薄预混合发光层（UPL）实现荧光白光有机电致发光器件（OLED）色彩精细控制的方法。UPL由两种染料的混合物组成（发红光的4-二（4 '-叔丁基联苯-4-基）氨基-4'-二氰基乙烯基苯或FVIN和发绿光的4-二（4 '-叔丁基联苯-4-基）氨基-4'-二氰基乙烯基苯或FVIN）（4 ′-叔丁基联苯-4-基）氨基苯甲醛或FCHO）在单个蒸发池中预混合：由于这两种分子具有相当的结构和相似的熔融温度，因此可以蒸发共混物，产生与预混合物的组成相比具有相同和可再现组成的薄膜。通过在标准荧光OLED结构的空穴传输层（4，4 '-双[N-（1-萘基）-N-苯基氨基]联苯（α-NPB））内蒸发1 nm厚的该共混物层来证明精细颜色调节的原理。当在空穴传输层内部的UPL的位置上以及在预混物组合物上起作用时，两个独立的参数可用于精细地控制发射的颜色。与异质结的蓝光发射相结合，获得了具有Commission Internationale de l 'Eclairage 1931色坐标（0.34，0.34）的白光，具有优异的注入电流的颜色稳定性。光谱显示，fcho材料由于有效的能量转移到红色发光的fvin化合物而不发光，但起到了fvin基质的作用，允许非常精确地调节器件中红色掺杂剂的量。
