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| Open AccessStable and efficient pure blue quantum-dot LEDs enabled by inserting an anti-oxidation layer
Blue QD-LEDs suffer from poor operational stability due to the carrier accumulation at transport layers. Here, the authors propose a strategy to mitigate the hole accumulation driven oxidation in hole transport layer, effectively elongating the operational lifetime of blue QD-LEDs.
- Wenjing Zhang
- , Bo Li
- & Huaibin Shen
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| Open AccessAnomalous efficiency elevation of quantum-dot light-emitting diodes induced by operational degradation
Quantum-dot light-emitting diodes may exhibit anomalous efficiency enhancement upon electrical stress, as revealed by the authors, resulting from the continuous deterioration of cathode contacts.
- Siyu He
- , Xiaoqi Tang
- & Yizheng Jin
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Article
| Open Access3.5 × 3.5 μm2 GaN blue micro-light-emitting diodes with negligible sidewall surface nonradiative recombination
Here Wang et al. demonstrate the fabrication of GaN micro-light emitting diodes with a low rate of efficiency decrease in low current density regions, these features are strongly desired for augmented-reality glass applications.
- Xuelun Wang
- , Xixi Zhao
- & Seiji Samukawa
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| Open AccessBidirectional light-emitting diode as a visible light source driven by alternating current
The bidirectional light-emitting diode emits visible light regardless of the direction of current flow, leading to AC applications. This is made possible by the use of two oppositely oriented tunnel junctions that surround the active region.
- Mikołaj Żak
- , Grzegorz Muziol
- & Czesław Skierbiszewski
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| Open AccessWafer-scale organic-on-III-V monolithic heterogeneous integration for active-matrix micro-LED displays
The electrical properties of solution deposited organic semiconductor channels are sensitive to substrate surface and processing conditions. Here, authors develop organic-last-integration technology to fabricate multilayer organic thin film transistor material stack onto micro light-emitting diode.
- Lei Han
- , Simon Ogier
- & Xiaojun Guo
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| Open AccessHigh-efficiency, flexible and large-area red/green/blue all-inorganic metal halide perovskite quantum wires-based light-emitting diodes
Cao et al. reports highly efficient, flexible, and larger-area Red/Green/Blue perovskite light-emitting diodes based on all-inorganic metal halide perovskite quantum wires arrays fabricated by porous alumina membranes assisted solution method.
- Yang Bryan Cao
- , Daquan Zhang
- & Zhiyong Fan
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| Open AccessUltra-low-current driven InGaN blue micro light-emitting diodes for electrically efficient and self-heating relaxed microdisplay
The size-dependent efficiency degradation issues of micro-light-emitting diodes are obstacles for efficient microdisplays development. Here, Baek et al. demonstrate an epitaxial engineering strategy to alleviate the efficiency degradations and achieve low operating temperature of pixels.
- Woo Jin Baek
- , Juhyuk Park
- & Sang Hyeon Kim
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Article
| Open AccessA sub-wavelength Si LED integrated in a CMOS platform
Integrated photonic systems require nanoscale on-chip light sources. Here Li et al., fabricate a silicon chip with LEDs smaller than the wavelength of light. This characteristic implies a partially coherent light emission, which allows the realization of an all-silicon holographic microscope.
- Zheng Li
- , Jin Xue
- & Rajeev J. Ram
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Article
| Open AccessBlue light-emitting diodes based on colloidal quantum dots with reduced surface-bulk coupling
The surface localized charges in colloidal quantum dots induce a degradation that limits the electroluminescence performance. Here, Chen et al. propose quantum dots with monmonotonically-graded core/shell/shell structures to boost the device’s performance by reducing the surface-bulk coupling.
- Xingtong Chen
- , Xiongfeng Lin
- & Song Chen
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| Open AccessLight sources with bias tunable spectrum based on van der Waals interface transistors
Here, the authors report the realization of light-emitting field-effect transistors based on van der Waals heterostructures with conduction and valence band edges at the Γ-point of the Brillouin zone, showing electrically tunable and material-dependent electroluminescence spectra at room temperature.
- Hugo Henck
- , Diego Mauro
- & Alberto F. Morpurgo
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Article
| Open AccessTowards n-type conductivity in hexagonal boron nitride
Asymmetric n/p conductivity is a fundamental difficulty in wide bandgap semiconductors. Here the authors demonstrate a concept of orbital level engineering through sacrificial impurity coupling to achieve n-type conductivity (ne ~1016 cm-3) in hexagonal BN.
- Shiqiang Lu
- , Peng Shen
- & Junyong Kang
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Article
| Open AccessMn2+-activated dual-wavelength emitting materials toward wearable optical fibre temperature sensor
Dual-wavelength emission materials can provide fluorescence intensity ratio technology with self-calibration features; their fabrication however, remains a challenge. Here, authors design a dual-wavelength emitting material Li2ZnSiO4:Mn2+ and present a wearable optical fibre temperature sensor, functioning in both contact and noncontact modes.
- Enhai Song
- , Meihua Chen
- & Qinyuan Zhang
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| Open AccessAnisotropic nanocrystal superlattices overcoming intrinsic light outcoupling efficiency limit in perovskite quantum dot light-emitting diodes
Controlling the transition-dipole-moment orientation in quantum dot solids at device level has not been achieved before. Here, the authors demonstrated intrinsic light out-coupling enhancement approach to boost the external quantum efficiency up to 25% by using the colloidal lead halide perovskite anisotropic nanocrystals.
- Sudhir Kumar
- , Tommaso Marcato
- & Chih-Jen Shih
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| Open AccessQuantum dot-integrated GaN light-emitting diodes with resolution beyond the retinal limit
Augmented reality technologies typically rely on near-eye displays, which requires displays with very high resolutions. Here, Bae et al demonstrate a quantum-dot integrated GaN light emitting diode arrays with a pixels per inch resolution of 1270, well beyond the retinal limit.
- Junho Bae
- , Yuseop Shin
- & Seunghyun Lee
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| Open AccessThermal assisted up-conversion electroluminescence in quantum dot light emitting diodes
How holes are injected into quantum dots at sub-bandgap bias has puzzled researchers for years. Here, authors show, using temperature-dependent electroluminescence (EL) and theoretical analysis, such injection occurs via thermal-assisted thermionic-emission, consequently enabling the sub-bandgap turn-on and up-conversion EL.
- Qiang Su
- & Shuming Chen
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| Open AccessDeep-ultraviolet electroluminescence and photocurrent generation in graphene/hBN/graphene heterostructures
Here, the authors report the observation of deep-ultraviolet (DUV) electroluminescence and photocurrent generation in van der Waals heterostructures based on hBN crystals, showing potential for DUV light emitting and detection devices.
- Su-Beom Song
- , Sangho Yoon
- & Jonghwan Kim
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Article
| Open AccessIntermediate-phase-assisted low-temperature formation of γ-CsPbI3 films for high-efficiency deep-red light-emitting devices
Exploiting low-temperature formed black phase CsPbI3 for light-emitting applications remains a challenge. Here, the authors propose a method to enable the deposition of γ-CsPbI3 films at 100C and demonstrate a light-emitting diode with an external quantum efficiency of 10.4% with suppressed efficiency roll-off.
- Chang Yi
- , Chao Liu
- & Jianpu Wang
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Article
| Open AccessBroadband infrared LEDs based on europium-to-terbium charge transfer luminescence
Broadband near-infrared (IR) light-emitting diodes (LEDs) are desirable for smart devices and bio-imaging applications, but the efficiency is limited by the phosphor materials. The authors report broadband emission in Eu-Tb co-doped CaS due to metal-to-metal charge transfer between dopants, and build a broadband near-IR LED with output surpassing the state of the art.
- Jonas J. Joos
- , David Van der Heggen
- & Luis Seijo
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| Open AccessThermodynamic-driven polychromatic quantum dot patterning for light-emitting diodes beyond eye-limiting resolution
Designing quantum dot light emitting diodes with full-colour pixel arrays with sub-micron feature size remains a challenge. Here, the authors demonstrate red-green-blue quantum dots arrays with resolutions up to 368 pixels per degree by leveraging thermodynamic-driven immersion transfer-printing.
- Tae Won Nam
- , Moohyun Kim
- & Yeon Sik Jung
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| Open AccessQuantum-dot and organic hybrid tandem light-emitting diodes with multi-functionality of full-color-tunability and white-light-emission
Designing efficient light-emitting diodes with full-color-tunability and white-light-emission remains a challenge. Here, the authors demonstrate a multifunctional hybrid tandem LED by stacking a yellow quantum-dot LED with a blue organic LED using an indium–zinc oxide intermediate connecting electrode.
- Heng Zhang
- , Qiang Su
- & Shuming Chen
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| Open AccessHighly efficient phosphor-glass composites by pressureless sintering
Phosphor-glass/ceramic composites are attractive for high-power white light-emitting diodes, but interfacial reaction leads to loss of quantum efficiency. Here the authors report a reduction sintering method for embedment of phosphors into silica glass with limited interfacial reaction.
- Dao Zhang
- , Wenge Xiao
- & Jianrong Qiu
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Article
| Open AccessExtrinsic nature of the broad photoluminescence in lead iodide-based Ruddlesden–Popper perovskites
The Ruddlesden–Popper type of halide perovskites are gaining interest but the origin of their broad band emission remains elusive. Here Kahmann et al. suggest that in-gap states, instead of the commonly believed self-trapped excitons, are responsible for the broad band emission in crystalline samples.
- Simon Kahmann
- , Eelco K. Tekelenburg
- & Maria A. Loi
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| Open AccessExciton diffusion in two-dimensional metal-halide perovskites
The so-called two-dimensional (2D) layered perovskites possess distinct optoelectronic properties from their 3D counterparts due to their reduced dimensionality. Here Seitz et al. investigate the exciton transport dynamics in 2D perovskites and highlight the impact of the stiffness of the lattice.
- Michael Seitz
- , Alvaro J. Magdaleno
- & Ferry Prins
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| Open AccessElectrochemically-stable ligands bridge the photoluminescence-electroluminescence gap of quantum dots
New design principles for bridging the photoluminescence and electroluminescence of colloidal quantum dots are needed. In this work, the authors report electrochemically-inert ligands as a general material-design strategy for realizing high-performance LEDs based on quantum dots.
- Chaodan Pu
- , Xingliang Dai
- & Xiaogang Peng
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| Open AccessSr[Li2Al2O2N2]:Eu2+—A high performance red phosphor to brighten the future
Developing innovative materials for reduced energy consumption in phosphor converted white light-emitting diodes remains a challenge. Here, the authors report a narrow band red-emitting oxonitride material with a highly symmetrical Sr2 + coordination for energy efficient white light-emitting diodes.
- Gregor J. Hoerder
- , Markus Seibald
- & Hubert Huppertz
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| Open AccessModulation of recombination zone position for quasi-two-dimensional blue perovskite light-emitting diodes with efficiency exceeding 5%
Halide perovskite based light-emitting diodes attracted intensive research interest recently but the efficiency of blue diodes is much lower than the green and red ones. Here Li et al. push up the efficiency of blue diodes through composition engineering and vertical morphology control.
- Zhenchao Li
- , Ziming Chen
- & Yong Cao
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Article
| Open AccessOn the degradation mechanisms of quantum-dot light-emitting diodes
Wide application of quantum dot light emitting diodes (QLED) in display technology is hindered by the poor lifetime of the blue QLEDs. Here, the degradation mechanism is shown to originate from space charge accumulation in the electron-transporting layer enabling improvements in blue QLED lifetimes.
- Song Chen
- , Weiran Cao
- & Lei Qian
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Article
| Open AccessHybrid perovskite light emitting diodes under intense electrical excitation
Hybrid perovskite semiconductors are promising for wavelength-tunable laser diodes but their behavior under intense electrical excitation remains unexplored. Kim et al. investigate perovskite light emitting diodes at current densities nearing 1 kA cm−2 and suggest that a laser diode is within reach.
- Hoyeon Kim
- , Lianfeng Zhao
- & Noel C. Giebink
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| Open AccessIdentifying an efficient, thermally robust inorganic phosphor host via machine learning
Identifying phosphors with good thermal stability and quantum efficiency is a prerequisite to improve the performance of white LED light sources. Here, a combined machine learning and density functional theory method is introduced to identify next generation inorganic phosphors.
- Ya Zhuo
- , Aria Mansouri Tehrani
- & Jakoah Brgoch
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| Open AccessColor-stable highly luminescent sky-blue perovskite light-emitting diodes
Perovskite light-emitting diodes show promising color tunability and device performance but suffer from emission color shift at higher driving voltages. Here Xing et al. report color stable blue light-emitting diodes by drastically increasing the phase purity of the quasi-2D perovskite thin films.
- Jun Xing
- , Yongbiao Zhao
- & Edward H. Sargent
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| Open AccessWaveguide-coupled nanopillar metal-cavity light-emitting diodes on silicon
Despite much progress, nanoscale light sources suitable for photonic integration are lacking. Here, the authors present a metal-cavity nanopillar LED on a silicon substrate working at telecommunications wavelengths, which demonstrates compatibility with membrane-on-Si photonic integration platforms.
- V. Dolores-Calzadilla
- , B. Romeira
- & D. Heiss
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Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices
Light-emitting diodes in the form of nanocrystals offer promise for environmental and biomedical diagnostics. Brovelliet al. present a method for realizing mechanically robust and chemically stable nanocrystals emitting light in the ultraviolet range.
- Sergio Brovelli
- , Norberto Chiodini
- & Alberto Paleari