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Article
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Plasma electron acceleration driven by a long-wave-infrared laser
The laser pulses that drive most laser wakefield accelerators have wavelengths near 1 micrometer and peak power > 100 terawatts. Here, the authors drive plasma wakes with 10 micrometer, 2-terawatt pulses, yielding relativistic electron beams with a collimated, narrow-energy-bandwidth component.
- R. Zgadzaj
- , J. Welch
- & M. C. Downer
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Article
| Open Access
Photonic time-crystalline behaviour mediated by phonon squeezing in Ta2NiSe5
Photonic time crystal refers to a material whose dielectric properties oscillate in time. Here the authors theoretically show such behaviour in the excitonic insulator candidate Ta2NiSe5 under optical excitation and use it to explain the enhanced THz reflectivity recently observed in pump-probe experiments
- Marios H. Michael
- , Sheikh Rubaiat Ul Haque
- & Eugene Demler
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Article
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Household alternating current electricity plug-and-play quantum-dot light-emitting diodes
Conventional lighting requires an AC-DC converter for LEDs. Here, the authors report a tandem structure by connecting two QLEDs with opposite polarity in parallel, enabling AC driven operation. A household AC electricity plug-and-play QLEDs panel with tuneable colour and brightness is achieved.
- Jiming Wang
- , Cuixia Yuan
- & Shuming Chen
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Bright, efficient, and stable pure-green hyperfluorescent organic light-emitting diodes by judicious molecular design
The device performance of pure-green hyperfluorescent organic light-emitting diodes remains unsatisfactory. Here, the authors report multi-resonance emitters with extended π−conjugation or increased donor strength, resulting in bright, efficient and stable pure-green hyperfluorescent devices.
- Yi-Ting Lee
- , Chin-Yiu Chan
- & Chihaya Adachi
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Article
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Onion-like multicolor thermally activated delayed fluorescent carbon quantum dots for efficient electroluminescent light-emitting diodes
Shi et al. report the synthesis of multicolour thermally activated delayed fluorescent carbon dots with 3D onion-like configuration to stabilise the triplet state and reduce the singlet-triplet energy gap. LEDs with EQE of 6.0–9.9% are achieved, a step further for efficient and stable displays.
- Yuxin Shi
- , Yang Zhang
- & Louzhen Fan
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Article
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Modified t-butyl in tetradentate platinum (II) complexes enables exceptional lifetime for blue-phosphorescent organic light-emitting diodes
It has been challenging to realize efficient and stable blue phosphorescent organic light-emitting diodes. Here, authors explore the effect of substitution position in platinum(II) dopants with suppressed metal-metal-to-ligand charge transfer features, resulting in prolonged lifetime in the devices.
- Young Hun Jung
- , Gyeong Seok Lee
- & Jang Hyuk Kwon
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Article
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Highly efficient multi-resonance thermally activated delayed fluorescence material toward a BT.2020 deep-blue emitter
The realization of a BT.2020 blue emitter is challenging due to the spectral redshift associated with π-extension. Here, the authors report a multi-resonance thermally activated delayed fluorescence emitter, exhibiting ultrapure deep-blue narrow emission and CIEy ≤ 0.05 exceeding 20% efficiency.
- Junki Ochi
- , Yuki Yamasaki
- & Takuji Hatakeyama
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Article
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Quantifying the interfacial triboelectricity in inorganic-organic composite mechanoluminescent materials
Mechanoluminescence enables sensing applications of mechanical stimuli. Here, the authors reveal the importance of interfacial triboelectricity to this phenomenon in inorganic-organic composite materials.
- Xin Pan
- , Yixi Zhuang
- & Rong-Jun Xie
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Article
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Direct space–time manipulation mechanism for spatio-temporal coupling of ultrafast light field
Here the authors propose a mechanism for direct space-time manipulation of ultrafast light field and experimentally demonstrate the generation of a spatiotemporally coupling light spring with a broad topological charge bandwidth.
- Qinggang Lin
- , Fu Feng
- & Xiaocong Yuan
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Article
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Compact terahertz harmonic generation in the Reststrahlenband using a graphene-embedded metallic split ring resonator array
Compact sources in the frequency range of 6-12 THz are difficult to obtain due to optical phonon absorption in conventional III-V semiconductors. Here, the authors demonstrate third harmonic generation at 9.63 THz by optically pumping monolayer graphene coupled to a circular split ring resonator by using a semiconductor laser.
- Alessandra Di Gaspare
- , Chao Song
- & Miriam S. Vitiello
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Comment
| Open Access
BerkSEL: A scale-invariant laser beyond the Schawlow-Townes two-mirror strategy
I argue that a surface emitting laser that remains single mode irrespective of its size, a scale-invariant laser, should of necessity also waste light at the edge. This is a fundamental departure from the Schawlow-Townes two-mirror strategy that keeps light away from mirrors and edges to preserve gain and minimize loss. The strategy was implemented in the recent discovery of the Berkeley Surface Emitting Laser (BerkSEL).
- Boubacar Kanté
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Article
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Modulation-free laser stabilization technique using integrated cavity-coupled Mach-Zehnder interferometer
Stable lasers are crucial in many applications like sensing. Here, the authors demonstrate a laser frequency locking method that maintains performance, eliminates modulation, simplifies architecture, and enables miniaturization on a photonic chip.
- Mohamad Hossein Idjadi
- , Kwangwoong Kim
- & Nicolas K. Fontaine
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Article
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Dual-color emissive OLED with orthogonal polarization modes
The authors present a switchable dual colour orthogonal linear polarized OLED by internally integrating a nanograting for selective diffraction of optical modes, which is appealing for applications including polarisation-encrypted colourful optical images and autostereoscopic naked-eye 3D displays.
- Ruixiang Chen
- , Ningning Liang
- & Tianrui Zhai
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Antireflective vertical-cavity surface-emitting laser for LiDAR
The authors showcase an innovative anti-reflective vertical-cavity surface-emitting laser (AR-VCSEL) that achieves low divergence and maintains a single-mode lasing. The 6-junction AR-VCSEL array demonstrates low divergence from 8° to 16° (D86) and tripled brightness compared to conventional counterparts. The AR-VCSEL offers an excellent avenue for long-distance LiDARs.
- Cheng Zhang
- , Huijie Li
- & Dong Liang
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Article
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Spatio-spectral 4D coherent ranging using a flutter-wavelength-swept laser
Solid-state spatio-spectral coherent light detection and ranging system is proposed based on flutter-wavelength-swept laser for real-time four-dimensional coherent imaging over extended measurable distance even in challenging environments.
- Dawoon Jeong
- , Hansol Jang
- & Chang-Seok Kim
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Article
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Manipulating solvent fluidic dynamics for large-area perovskite film-formation and white light-emitting diodes
Achieving large-area uniform film is the primary challenge to commercialise perovskite LEDs. The authors here employ green binary solvents to regulate the fluidic dynamics in perovskite quantum dot inks during blade-coating to achieve efficient 28 cm2-sized red and white perovskite LEDs.
- Guangyi Shi
- , Zongming Huang
- & Zhengguo Xiao
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Article
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Rapid synthesis of phosphor-glass composites in seconds based on particle self-stabilization
Phosphor-glass composites can serve as efficient and stable photonic converters, but their synthesis generally requires harsh and time-consuming procedures. Here, the authors report an alternative synthesis route that requires only a few seconds and is based on particle self-stabilization.
- Yongsheng Sun
- , Yuzhen Wang
- & Zhiguo Xia
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Article
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Stable 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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Article
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Efficient, narrow-band, and stable electroluminescence from organoboron-nitrogen-carbonyl emitter
Multi-resonance thermally activated delayed fluorescent emitters composed of only period-2 elements are important for achieving comprehensive performances. Here, authors report hybridization of organoboron-nitrogen and carbonyl groups in the emitter to achieve a long device operational stability.
- Ying-Chun Cheng
- , Xun Tang
- & Xiao-Hong Zhang
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Article
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Active mid-infrared ring resonators
Multifunctional active mid-infrared ring resonators and directional couplers with quantum cascade laser cores allow electrical control of resonant frequency and quality factors, tunable filtering and frequency comb generation.
- Dmitry Kazakov
- , Theodore P. Letsou
- & Federico Capasso
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Article
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A mode-locked random laser generating transform-limited optical pulses
Pulses of adjustable duration are generated by a mode-locked random fibre laser that can drive advances in sensing. Rayleigh backscattering from cm-long sections of telecom fibre provides laser feedback and spectral selectivity to the Fourier limit.
- Jean Pierre von der Weid
- , Marlon M. Correia
- & Walter Margulis
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Article
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Turnkey photonic flywheel in a microresonator-filtered laser
Here the authors demonstrate a universal approach to achieve turnkey dissipative Kerr soliton (DKS) frequency comb. Phase insensitivity, self-healing capability, deterministic selection of DKS state, and access to ultralow noise are all successfully accomplished.
- Mingming Nie
- , Jonathan Musgrave
- & Shu-Wei Huang
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Article
| Open Access
Tracking exceptional points above the lasing threshold
The authors report on the experimental observation and characterization of exceptional points above the lasing threshold in photonic crystal nanocavities.
- Kaiwen Ji
- , Qi Zhong
- & Alejandro M. Yacomotti
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Article
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Photon-phonon collaboratively pumped laser
Ultrahigh-efficiency and low-threshold yet tunable and compact laser devices are at the base of new functional devices. Here the authors harness a new temperature degree of freedom to realize a tunable photon-phonon collaboratively pumped laser.
- Yu Fu
- , Fei Liang
- & Yan-Feng Chen
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Article
| Open Access
Direct identification of interfacial degradation in blue OLEDs using nanoscale chemical depth profiling
Understanding the degradation mechanism of organic light-emitting diodes is essential to improve device performance and stability. Here, authors present a high-resolution diagnostic method to obtain molecular information with 7-nm depth resolution and analyse devices at different degradation levels.
- Gustavo F. Trindade
- , Soohwan Sul
- & Ian S. Gilmore
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Article
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Anomalous 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
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3.5 × 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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Article
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Bidirectional 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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Critical role of electrons in the short lifetime of blue OLEDs
Designing robust blue organic light-emitting diodes is a long-standing challenge in the display industry. Here, the authors show that electron-induced degradation reactions play a more critical role in the short lifetime of devices with iridium-based emitters under real operational conditions.
- Jaewook Kim
- , Joonghyuk Kim
- & Woo Youn Kim
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Article
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Large area inkjet-printed OLED fabrication with solution-processed TADF ink
Low-cost manufacturing of large-scale thermally activated delayed fluorescence organic light-emitting diodes has been restricted due to their incompatibility with solution processing techniques. Here, authors develop inkjet printing ink formulation to fabricate patterns without use of lithography.
- Chandra Kant
- , Atul Shukla
- & Monica Katiyar
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Article
| Open Access
Prediction on X-ray output of free electron laser based on artificial neural networks
Methods to characterize the free-electron laser pulses are evolving and their performances are also improving. Here the authors demonstrate a method based on the artificial neural networks to predict the output pulses of the X-ray free-electron laser by considering the electron beam parameters as input.
- Kenan Li
- , Guanqun Zhou
- & Anne Sakdinawat
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Article
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Highly efficient octave-spanning long-wavelength infrared generation with a 74% quantum efficiency in a χ(2) waveguide
A χ(2) nonlinear micro-waveguide platform is demonstrated based on the birefringence phase matching for simple and efficient long-wavelength infrared generation, which could trigger new frontiers of MIR integrated nonlinear photonics.
- Bo Hu
- , Xuemei Yang
- & Houkun Liang
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Article
| Open Access
Double boron–oxygen-fused polycyclic aromatic hydrocarbons: skeletal editing and applications as organic optoelectronic materials
The development of chemically diverse boron-oxygen-fused polycyclic aromatic hydrocarbons has been limited by their synthetic complexity. Here, authors report a one-pot strategy for their facile synthesis and demonstrate their potential as ultralong afterglow and host materials for deep-blue OLEDs.
- Guijie Li
- , Kewei Xu
- & Yuan-Bin She
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Article
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Wafer-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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Nanoscale reshaping of resonant dielectric microstructures by light-driven explosions
Laser machining can modify and reshape materials on the scale comparable to light’s wavelength. Here, authors use tailored microstructures to push the limit of laser machining to a scale that is almost 100 times smaller than a wavelength of light.
- Maxim R. Shcherbakov
- , Giovanni Sartorello
- & Gennady Shvets
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Article
| Open Access
A random optical parametric oscillator
In this work the authors develop a Random optical parametric oscillator - the parametric analogous of random lasers. This system shows improved key metrics like tuneable repetition rates, tuneable pulse duration, inter-pulse coherence as well as simpler configuration compared with standard systems.
- Pedro Tovar
- , Jean Pierre von der Weid
- & Xiaoyi Bao
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Article
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Enhancing operational stability of OLEDs based on subatomic modified thermally activated delayed fluorescence compounds
Structural engineering at the subatomic level remains little for boosting operational stability of organic light-emitting diodes. Here, authors show that deuteration of acceptor is critical to enhance device stability, which is commonly neglected due to limited availability and synthetic complexity.
- Sinyeong Jung
- , Wai-Lung Cheung
- & Man-Chung Tang
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Article
| Open Access
Charge injection engineering at organic/inorganic heterointerfaces for high-efficiency and fast-response perovskite light-emitting diodes
The hole injection and device stability rely heavily on the inorganic/organic interface in perovskite light-emitting diodes. The authors enhanced the NiOx/PVK interface with a self-assembled monolayer, resulting in blue and green devices with maximum efficiencies of 14.5% and 26.0%, respectively.
- Zhenchao Li
- , Ziming Chen
- & Hin-Lap Yip
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Article
| Open Access
Electroluminescence and hyperphosphorescence from stable blue Ir(III) carbene complexes with suppressed efficiency roll-off
Deep-blue emitters and corresponding light-emitting devices are still in the progress to meet industrial standards. Here, the authors report catalytic interconversion of isomeric iridium(III) complexes and achieve true-blue emission and operational half-lifetime of over 10,000 h for tandem devices.
- Jie Yan
- , Dong-Ying Zhou
- & Yun Chi
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Article
| Open Access
Orientation distributions of vacuum-deposited organic emitters revealed by single-molecule microscopy
The understanding of the orientation of luminescent molecules is currently limited by the ensemble-averaging nature of state-of-the-art measurements. Here, the authors apply single-molecule imaging to obtain complete orientation distributions of the transition dipole of individual emitter molecules.
- Francisco Tenopala-Carmona
- , Dirk Hertel
- & Malte C. Gather
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Article
| Open Access
Blue organic light-emitting diode with a turn-on voltage of 1.47 V
The requirement of a high applied voltage remains a critical issue for blue organic-light emitting diodes. Here, the authors determine the appropriate donor-acceptor combination for triplet-triplet annihilation upconversion emission, achieving a low turn-on voltage of 1.47 V in blue devices.
- Seiichiro Izawa
- , Masahiro Morimoto
- & Masahiro Hiramoto
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Article
| Open Access
Interlayer donor-acceptor pair excitons in MoSe2/WSe2 moiré heterobilayer
The nature of localized interlayer excitons (LIXs) in moiré superlattices is still elusive Here, the authors propose a donor-acceptor pair mechanism for LIXs in MoSe2/WSe2 heterobilayers.
- Hongbing Cai
- , Abdullah Rasmita
- & Weibo Gao
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Article
| Open Access
Multiple-core-hole resonance spectroscopy with ultraintense X-ray pulses
Intense light pulses can create nonlinear ionization processes in atoms and molecules. Here the authors study the photoionization of xenon atoms using intense free-electron laser pulses that can create extremely high charge states and produce hollow atoms, featuring up to six simultaneous core-holes.
- Aljoscha Rörig
- , Sang-Kil Son
- & Rebecca Boll
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Article
| Open Access
Laser-induced nitrogen fixation
Emerged sustainable techniques for nitrogen fixation still lack ammonia yield rate to be practically relevant. Here, the authors demonstrate a laser–induced method to deliver a yield rate of 30.9 µmol s-1 cm−2 at ambient conditions, which is two orders of magnitude higher than other methods.
- Huize Wang
- , Ranga Rohit Seemakurthi
- & Markus Antonietti
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Article
| Open Access
High-performance blue OLED using multiresonance thermally activated delayed fluorescence host materials containing silicon atoms
Effective energy transfer and suppressed dopant aggregation is critical for realizing efficient organic light-emitting diodes. Here, the authors report six host materials capable of exhibiting enhanced thermal stability and film-formation behavior, demonstrating efficiency of over 30% at 1000 cd/m2.
- Dongmin Park
- , Seokwoo Kang
- & Soo Young Park
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Article
| Open Access
An X-ray free-electron laser with a highly configurable undulator and integrated chicanes for tailored pulse properties
Since their initial operation, free-electron lasers are regularly upgraded in their performance and parameter control. Here the authors present the first lasing results of the soft X-ray free-electron laser beamline of the Paul Scherrer Institute, demonstrating different modes of operation and polarisation control of the tailored soft X-ray pulses.
- Eduard Prat
- , Andre Al Haddad
- & Tobias Weilbach
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Article
| Open Access
Minimizing non-radiative decay in molecular aggregates through control of excitonic coupling
Exciton delocalization in molecular aggregates is suggested to counteract the Energy Gap Law. Here, authors reveal the underlying physical picture and find the optimal excitonic coupling that minimizes nonradiative decay by nearly exact simulations.
- Yuanheng Wang
- , Jiajun Ren
- & Zhigang Shuai
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Article
| Open Access
Long operating lifetime mid-infrared LEDs based on black phosphorus
Mid-infrared light emitting diodes (LEDs) based on black phosphorus (BP) have shown promising performance, but they are usually limited by the environmental instability of the material. Here, the authors extrapolate a room-temperature operational lifetime of BP LEDs up to ~ 15,000 h via Al2O3 passivation and nitrogen seal packaging.
- Naoki Higashitarumizu
- , Shogo Tajima
- & Ali Javey
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Article
| Open Access
Hybridization of short-range and long-range charge transfer excited states in multiple resonance emitter
Multi resonance thermally activated delayed fluorescence emitters are the next-generation blue dopants for organic light-emitting diodes. Here, the authors develop two isomeric emitters with hybridized long-range and short-range charge transfer excited states and realize device efficiency of 30.8%.
- Ha Lim Lee
- , Jihoon Kang
- & Jun Yeob Lee
Inverted device architecture for high efficiency single-layer organic light-emitting diodes with imbalanced charge transport