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Article
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Stable pure-green organic light-emitting diodes toward Rec.2020 standard
It is essential to manipulate the dynamic behaviour of charge carriers and excitons in organic light-emitting diodes. Here, authors report the trapping of injected electrons by a thermally activated delayed fluorescence assistant molecule in a bipolar host matrix and achieve long device stability.
- Xun Tang
- , Tuul Tsagaantsooj
- & Chihaya Adachi
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Article
| Open Access
Inverted device architecture for high efficiency single-layer organic light-emitting diodes with imbalanced charge transport
Efficient organic light-emitting diodes require a multilayer architecture to confine charge recombination to the emissive layer. Here, authors demonstrate efficient single-layer devices for emitters with imbalanced charge transport without the need of additional charge transport or blocking layers.
- Xiao Tan
- , Dehai Dou
- & Gert-Jan A. H. Wetzelaer
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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
| Open Access
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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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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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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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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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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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
| Open Access
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
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
| Open Access
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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| 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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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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| 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
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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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| 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
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
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Article
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Mesitylated trityl radicals, a platform for doublet emission: symmetry breaking, charge-transfer states and conjugated polymers
Neutral π-radicals are potential emitters for optoelectronic devices due to the absence of energetically low-lying non-emissive states. Here, the authors report mesityl-substituted tris(2,4,6-trichlorophenyl)methyl radicals and achieve maximum device efficiency of 28% at a wavelength of 689 nm.
- Petri Murto
- , Rituparno Chowdhury
- & Hugo Bronstein
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Article
| Open Access
Carbene-stabilized enantiopure heterometallic clusters featuring EQE of 20.8% in circularly-polarized OLED
Chiral coinage metal clusters show promise for use in emerging circularly polarized light-emitting materials and diodes but research on efficient circularly polarized organic light-emitting diodes (CP-OLEDs) with enantiopure metal clusters remains elusive. Herein, the authors design a multidentate chiral N-heterocyclic carbene (NHC) ligand which is used in the synthesis of enantiopure Au(I)-Cu(I) clusters with exceptional stability and demonstrate application of these clusters in the fabrication of CP-OLEDs
- Xiao-Hong Ma
- , Jing Li
- & Shuang-Quan Zang
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| Open Access
Longevity gene responsible for robust blue organic materials employing thermally activated delayed fluorescence
High throughput virtual screening of robust blue thermally activated delayed fluorescent emitters has yet been implemented. Here, authors reveal a linear relationship of the difference between bond dissociate energy and first triplet state energy with the logarithm of device operational lifetime.
- Qing-Yu Meng
- , Rui Wang
- & Juan Qiao
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Article
| Open Access
Intramolecular charge transfer enables highly-efficient X-ray luminescence in cluster scintillators
X-ray luminescence efficiency of copper halide clusters is limited by nonradiative charge transfer. Here, Zhang et al. report highly emissive radioluminescence of Cu4I4 cubes by functionalizing biphosphine ligands with acridine, unlocking the potential use as low-cost and eco-friendly scintillators.
- Nan Zhang
- , Lei Qu
- & Hui Xu
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Article
| Open Access
Confining donor conformation distributions for efficient thermally activated delayed fluorescence with fast spin-flipping
The distribution of dihedral angles in film state has significant influence on excited state lifetimes of thermally activated delayed fluorescence emitters. Here authors report conformation distribution confinement strategy to achieve fast spin-flipping for efficient organic light-emitting diodes.
- Weidong Qiu
- , Denghui Liu
- & Shi-Jian Su
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Article
| Open Access
High-efficiency and stable short-delayed fluorescence emitters with hybrid long- and short-range charge-transfer excitations
To possess a small singlet-triplet energy gap and a large oscillator strength simultaneously is critical for efficient thermally activated delayed fluorescent emitters. Here, the authors attach an multiresonance-acceptor onto a sterically-uncrowded donor for realizing a device efficiency of 40.4%.
- Guoyun Meng
- , Hengyi Dai
- & Lian Duan
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Article
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Realizing efficient blue and deep-blue delayed fluorescence materials with record-beating electroluminescence efficiencies of 43.4%
Thermally activated delayed fluorescence materials are important for the development of OLED materials but the development of robust blue emitting materials remains challenging. Here, the authors report three highly efficient blue and deepblue delayed fluorescence materials demonstrating excellent electroluminescence performance.
- Yan Fu
- , Hao Liu
- & Zujin Zhao
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Article
| Open Access
Visualizing electroluminescence process in light-emitting electrochemical cells
The recombination between electrons and holes in electroluminescence processes has never been directly evaluated. Here, Yasuji et al. directly visualize, with spectroscopic techniques, operation dynamics in light-emitting electrochemical cells during device operation, leading to a rapid device evaluation.
- Kosuke Yasuji
- , Tomo Sakanoue
- & Katsuichi Kanemoto
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Article
| Open Access
Constructing high-efficiency orange-red thermally activated delayed fluorescence emitters by three-dimension molecular engineering
The design of high-efficiency solution-processable orange-red thermally activated delayed fluorescence (TADF) emitters remains to be a challenge. Here, the authors synthesize a series of emitters consisting of a trinaphtho[3,3,3]propellane core with highly efficient emission in the orange-red region of the spectrum.
- Lei Hua
- , Yuchao Liu
- & Zhongjie Ren
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Article
| Open Access
Synergistic passivation and stepped-dimensional perovskite analogs enable high-efficiency near-infrared light-emitting diodes
Defect-assisted nonradiative recombination and carrier aggregation at the interface hinder the potential of perovskites as emitter for light-emitting diodes. Here, Fang et al. achieve an external quantum efficiency of 24.1% by combining multidimensional perovskite with cascade conduction bands.
- Yongjie Liu
- , Chen Tao
- & Guojia Fang
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Article
| Open Access
A platform for blue-luminescent carbon-centered radicals
Organic radicals, which have unique doublet spin-configuration, provide an alternative method to overcome the efficiency limitation of organic light-emitting diodes (OLEDs) but extending their fluorescence into a short-wavelength region remains challenging. Here, the authors significantly expand the scope of luminescent radicals by showing a new platform of carbon-centered radicals that produce blue to green emission.
- Xin Li
- , Yi-Lin Wang
- & Ying-Feng Han
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Article
| Open Access
Fluorescence-based monitoring of the pressure-induced aggregation microenvironment evolution for an AIEgen under multiple excitation channels
The develop of organic functional materials requires the exploration of the pressure dependent emissive mechanisms of molecular structures, conformations and stacking modes. Here, Tong et al propose a strategy for monitoring the pressure-induced fluorescence under multiple excitation channels.
- Shuang Tong
- , Jianhong Dai
- & Xinggui Gu
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Article
| Open Access
All-fluorescence white organic light-emitting diodes with record-beating power efficiencies over 130 lm W‒1 and small roll-offs
High power efficiency and low roll-off values are essential to the commercialization of white organic light-emitting diodes. Here, the authors construct all-fluorescence devices with an orange emitting layer sandwiched between two sky-blue emitting layers, achieving figure-of-merit of 130.7 lm/W.
- Hao Liu
- , Yan Fu
- & Zujin Zhao
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Article
| Open Access
Toward a BT.2020 green emitter through a combined multiple resonance effect and multi-lock strategy
The authors combine multiple resonance effect and multi-lock strategy to dope green-emitting thermally activated delayed fluorescent molecules into green-emitting phosphorescence OLEDs by endowing the device with a Broadcast Service Television 2020 color-gamut, 50% improved EQE, and a high luminescence of half a million nits.
- Junyuan Liu
- , Yunhui Zhu
- & Qisheng Zhang
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| Open Access
Singlet and triplet to doublet energy transfer: improving organic light-emitting diodes with radicals
Organic light-emitting diodes must be engineered to circumvent efficiency limits imposed by the ratio of triplet to singlet exciton formation, following electron-hole capture. Here, authors unlock energy transfer channels between singlet, triplet and doublet excitons using thermally activated delayed fluorescence and radical emitters towards more efficient light-emitting devices.
- Feng Li
- , Alexander J. Gillett
- & Emrys W. Evans
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| Open Access
Probing polaron-induced exciton quenching in TADF based organic light-emitting diodes
Efficiency roll-off in organic light-emitting diodes under elevated current densities not only results in high power consumption but also device degradation. Here, the impact of polaroninduced quenching in efficiency roll-off was investigated and strategies to reduce efficiency roll-off were proposed.
- Monirul Hasan
- , Siddhartha Saggar
- & Ebinazar B. Namdas
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Article
| Open Access
Spontaneous exciton dissociation enables spin state interconversion in delayed fluorescence organic semiconductors
A low singlet-triplet energy gap, necessary for delayed fluorescence organic semiconductors, results in a small radiative rate that limits performance in OLEDs. Here, the authors show that it is possible to reconcile these conflicting requirements in materials that can access both high oscillator strength intramolecular excitations and intermolecular charge transfer states.
- Alexander J. Gillett
- , Claire Tonnelé
- & Richard H. Friend
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| Open Access
Hot exciplexes in U-shaped TADF molecules with emission from locally excited states
Molecular designs improving the performance of thermally activated delayed fluorescence (TADF) emitters are greatly desired for optoelectronic applications. The authors propose a molecular geometry with donor and acceptor moieties facing each other separated by an anthracene bridge, giving rise to hot exciplex states producing color pure and fast TADF emission.
- A. Lennart Schleper
- , Kenichi Goushi
- & Alexander J. C. Kuehne
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Article
| Open Access
Emergence and control of photonic band structure in stacked OLED microcavities
Understanding and manipulating the photonic band structure formed in stacked Fabry-Pérot microcavity organic light-emitting diodes (OLEDs) is key to optimizing their performance. Here, through intelligent device design, the authors tune the photonic band gap in vertically-stacked OLED microcavities.
- David Allemeier
- , Benjamin Isenhart
- & Matthew S. White
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Article
| Open Access
High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence
Thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) rely on high triplet energy interlayers to confine excitons, which results in reduced performance. Here, the authors report high-performance blue TADF-OLEDs with below bandgap electroluminescence.
- Maria Vasilopoulou
- , Abd. Rashid bin Mohd Yusoff
- & Nicola Gasparini
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Article
| Open Access
Electron spin resonance resolves intermediate triplet states in delayed fluorescence
Despite advances in the design of thermally activated delayed fluorescence (TADF) emitters for devices, the effect of spin interactions is not well understood. Here, the authors report the role of spin-vibronic coupling in TADF organic emitters using transient electron spin resonance spectroscopy.
- Bluebell H. Drummond
- , Naoya Aizawa
- & Emrys W. Evans
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Article
| Open Access
Ladder-like energy-relaying exciplex enables 100% internal quantum efficiency of white TADF-based diodes in a single emissive layer
Realizing efficient white organic light-emitting diodes (WOLEDs) with a single thermally-activated delayed fluorescence (TADF) emissive layer remains a challenge. Here, the authors design energy-relaying exciplex hosts with multi-triplet excited states for efficient single-emissive-layer TADF WOLEDs.
- Chunmiao Han
- , Ruiming Du
- & Wei Huang
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Article
| Open Access
Highly efficient, heat dissipating, stretchable organic light-emitting diodes based on a MoO3/Au/MoO3 electrode with encapsulation
A transparent twistable and stretchable MoO3/Au/MoO3 electrode is demonstrated by Choi et al. for organic light-emitting diodes. The device fabricated on thin elastomer shows enhanced EQE with minimum efficiency roll-off owing to the improved charge injection and heat dissipation from the substrate.
- Dae Keun Choi
- , Dong Hyun Kim
- & Seung Yoon Ryu
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Article
| Open Access
Unravelling the electron injection/transport mechanism in organic light-emitting diodes
Understanding the role electron injection and transport in organic light-emitting diodes (OLED) is critical for optimizing device performance. Here, the authors elucidate the electron injection/transport mechanism in OLEDs and identify the cathode/emissive layer energy barrier as the key factor.
- Tsubasa Sasaki
- , Munehiro Hasegawa
- & Hirohiko Fukagawa
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Article
| Open Access
Phenylalkylammonium passivation enables perovskite light emitting diodes with record high-radiance operational lifetime: the chain length matters
Perovskite light emitting diodes suffer from operational stability, showing rapid decay of performance within minutes to hours after turn-on. Here, the authors investigate how the steric and Coulomb interaction of ammonium passivation molecules with varying alkyl chain length can improve device stability by suppressing iodide ion migration.
- Yuwei Guo
- , Sofia Apergi
- & Ni Zhao
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Article
| Open Access
A substrateless, flexible, and water-resistant organic light-emitting diode
Though organic light-emitting diodes (OLEDs) with impressive flexibility have been reported, achieving stable operation in air and moist environments remains difficult. Here, the authors report ultrathin OLEDs with hybrid thin-film encapsulation barriers for stable operation in harsh environments.
- Changmin Keum
- , Caroline Murawski
- & Malte C. Gather
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Article
| Open Access
Segment-specific optogenetic stimulation in Drosophila melanogaster with linear arrays of organic light-emitting diodes
Organic light-emitting diodes (OLEDs) can offer an attractive approach for providing light stimulation in high-throughput optogenetics. Here, the authors report a microstructured OLED array that provides local photo-stimulation in Drosophila melanogaster larvae for controlled motor responses.
- Caroline Murawski
- , Stefan R. Pulver
- & Malte C. Gather
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Article
| Open Access
Suppression of external quantum efficiency rolloff in organic light emitting diodes by scavenging triplet excitons
Though organic light-emitting diodes are highly desirable for display and lighting applications, efficiency roll-off at high current densities limits its applicability. Here, the authors report a triplet scavenging strategy for improved triplet exciton management and reduced efficiency roll-off.
- Buddhika S. B. Karunathilaka
- , Umamahesh Balijapalli
- & Chihaya Adachi
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Article
| Open Access
Large cation ethylammonium incorporated perovskite for efficient and spectra stable blue light-emitting diodes
Blue light-emitting diodes (LEDs) are critical for displays. Employing a large organic cation into a quasi-two dimensional perovskite with green emission, Chu et al. achieve LEDs exhibiting a high external quantum efficiency of 12.1% and stable spectra in the sky-blue region.
- Zema Chu
- , Yang Zhao
- & Jingbi You
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Article
| Open Access
Kinetic prediction of reverse intersystem crossing in organic donor–acceptor molecules
Understanding and predicting the kinetics of reverse intersystem crossing (RISC) facilitates the design of materials. Here, the authors demonstrate a theoretical expression that reproduces experimental RISC rate constants ranging over five orders of magnitude in selected molecules.
- Naoya Aizawa
- , Yu Harabuchi
- & Yong-Jin Pu
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Article
| Open Access
Understanding coordination reaction for producing stable electrode with various low work functions
Despite recent studies aimed at realizing efficient charge injection and collection in organic electronics, developing stable organic injection materials remains a challenge. Here, the authors report phenanthroline derivative-based materials for improved charge injection in organic devices.
- Hirohiko Fukagawa
- , Kazuma Suzuki
- & Takahisa Shimizu
High-performance near-infrared OLEDs maximized at 925 nm and 1022 nm through interfacial energy transfer