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The recent introduction of organic light-emitting diode (OLED) monitors with refresh rates of 240 Hz or more opens new possibilities for their use as precise stimulation devices in vision research, experimental psychology, and electrophysiology. These affordable high-speed monitors, targeted at video gamers, promise several advantages over cathode ray tube (CRT) and liquid crystal display (LCD) monitors. Unlike LCDs, OLEDs have self-emitting pixels that can show true black, resulting in superior contrast, a broad color spectrum, and wide viewing angles. More importantly, the latest OLEDs offer excellent timing properties with minimal input lag and rapid transition times. However, OLED technology also has potential drawbacks, such as auto-brightness limiting (ABL), where luminance changes with the number of illuminated pixels. This study characterized a 240 Hz OLED monitor (ASUS PG27AQDM) in terms of its timing, temporal independence, spatial uniformity, viewing angles, warm-up time, and ABL behavior, and compared it with CRTs and LCDs. Results confirm excellent temporal performance, with CRT-like transition times, wide viewing angles, and good spatial uniformity. We show that ABL can be prevented with appropriate settings. However, we also report a novel type of luminance artifact on OLEDs, where high-contrast stimuli, shown for long durations, can create image persistence via localized warming or cooling of the panel. Finally, we demonstrate the monitor's benefits in two time-critical paradigms: rapid invisible flicker tagging (RIFT) and saccade-contingent display changes. The latest consumer OLEDs provide precise and cost-effective stimulation devices for time-critical experiments, although some caution is warranted in experiments involving long exposures to high-contrast stimuli.

Simultaneously realizing high internal quantum efficiency (IQE) and light outcoupling efficiency (LOE) in OLEDs solely depending on molecular engineering has never been achieved. Here, we design three OLED emitters (DCzPDO, DPhCzPDO, and DPAPDO), all comprising 3-hydroxypropenone and β-diketone tautomers. One prominent feature of them is hot-exciton emission enabled by high-lying reverse intersystem crossing (hRISC), hence significantly improving material electroluminescence. Interestingly, in DPAPDO, both isomers exhibit hot-exciton fluorescence, while in the other two materials, only the β-diketone tautomer demonstrates this feature. On the other hand, these materials possess different degrees of preferential transition-dipole-moment alignment, promoting light extraction in OLEDs. Furthermore, their molecules tend to self-assemble along 1D directions, inducing a quasi-parallel V-shaped nanogroove, significantly enhancing light outcoupling in devices. Among them, DPAPDO achieves the highest device performance, reaching a maximum external quantum efficiency (EQE) of 23.7%. DPAPDO comprises the highest concentration of β-diketone isomer, with both isomers facilitating effective hRISC transitions, leading to a near unity IQE of luminescence. Additionally, DPAPDO displays the highest-quality film nanostructure and moderate horizontal dipole ratio, thereby achieving a high LOE of 57%. All these factors account for its high OLED performance. The synergistic interplay between electroluminescence and molecular/supramolecular structures paves the way for cost-effective, scalable, high-efficiency OLEDs.

Organometallic phosphorescent materials have been developed as critical luminescent materials for organic light-emitting diodes (OLEDs). However, most purely organic room-temperature phosphorescence (RTP) materials without any heavy metals still lack competitiveness for use in OLEDs. Recently, significant progress has been made regarding purely organic RTP materials, and their electroluminescence (EL) performances have become comparable to those of traditional phosphorescent complexes. In this perspective, advancements and proposed design strategies relating to efficient purely organic RTP materials are summarized. Furthermore, the promising application of these RTP materials as sensitizers for narrow-spectrum multi-resonance emitters is also discussed and an outlook is provided, which is conducive to the development of high-resolution OLEDs. It is expected that this perspective will provide valuable guidelines for advancing robust purely organic RTP sensitizers and further promoting the OLED industry.

Color purity, device lifetime, and external quantum efficiency (EQE) serve as critical performance metrics for high-quality organic light-emitting diodes (OLEDs), yet these remain the primary bottlenecks in the development of exciplex-based OLEDs. Here, we developed a construction strategy for efficient thermally activated delayed fluorescence (TADF) exciplexes with narrowband emission by introducing a multiresonance TADF (MR-TADF) donor. The highly planar MR-TADF molecule SYBN and derivatives of 2,4,6-triphenyl-1,3,5-triazine (3N) are employed, resulting in driving forces of the exciplex formation (ΔGCS) up to 1.2 eV and strong intermolecular charge-transfer characteristics. These features enable the resulting exciplexes to exhibit high photoluminescence quantum yield (PLQY) up to 89% with narrow full-width at half-maximum (FWHM) down to 60 nm and fast reverse intersystem crossing rate (kRISC). Device performance characterization reveals that OLED devices based on this system demonstrate excellent comprehensive performance: the optimal device achieves a high EQE of 27.28%, a narrow FWHM of only 60 nm, and an extrapolated LT50 operational lifetime exceeding 6,000 h at an initial luminance of 1,000 cd m-2. This research not only breaks the performance records of exciplex-based OLEDs but also provides a new paradigm for the design and development of ideal exciplex luminescent materials.

To advance wearable medical technology beyond its current limits, stretchable organic light-emitting diode (SOLED) displays must become practical. Achieving this requires both mechanical softness and durable environmental protection, yet conventional SOLED platforms are limited by a resolution-stretchability trade-off and the fracture-prone nature of inorganic encapsulation layers. Here we report a multilayer SOLED architecture that separates light emission and mechanical deformation into vertically stacked planes. By decoupling emissive pixel islands from deformable interconnects, the design enables high-fill-factor pixel patterning while improving mechanical compliance and structural reliability. Finite-element analysis and experimental measurements show that the multilayer stack redistributes tensile strain into compliant elastomeric layers, delivering approximately 54% system-level stretchability. Stable electroluminescence is maintained under repeated loading and 50% uniaxial tensile strain. For outdoor and long-term operation, we further develop a hybrid encapsulation combining atomic-layer-deposited nanolaminate distributed Bragg reflector layers with parylene-C. The resulting barrier exhibits a barrier performance of 1.26 × 10- 6 g m- 2 day- 1, achieves 99.87% ultraviolet blocking, and preserves device operation under cyclic deformation and hygrothermal stress. In a murine wound-healing model, the SOLED patch conformally covered skin and accelerated healing by over 50% compared with controls, demonstrating its strong potential for wearable therapeutic applications.

Achieving efficient and stable blue solution-processed OLEDs remains an outstanding challenge in the field. We introduce a rational donor decoration strategy and apply it to the TADF emitter DOBNA-SpAc (aka. TDBA-SAF), exemplified in the emitter DOBNA-SpAc-DCz. By introducing ter(tert-butylcarbazole) units at the 2 and 7 positions of the acridine moiety, solubility and hole-transport properties are improved without compromising the blue emission endemic to DOBNA-SpAc. This emitter has a high photoluminescence quantum yield, ΦPL, of 93% in 20 wt.% doped films in PPF (2,8-bis(diphenyl-phosphoryl)-dibenzo[b,d]furan), a very small singlet-triplet energy gap (ΔEST = 0.01 eV), and thus fast reverse intersystem crossing (kRISC > 1 × 106 s-1), resulting in a short delayed lifetime of 2 µs. Solution-processed OLEDs with DOBNA-SpAc-DCz reached a maximum external quantum efficiency, EQEmax, of 29.4 ± 0.1% at CIE coordinates of (0.145, 0.211). By probing different electron transport materials and comparing to devices using DOBNA-SpAc, we found that the introduction of carbazole substituents promotes improved hole transport and a more spatially distributed recombination zone, while the faster kRISC suppresses triplet-related annihilation processes. These results demonstrate that the targeted peripheral donor dendron decoration of spiroacridine-based TADF emitters is an effective strategy to achieve highly efficient emitters suitable for solution-processed OLED applications.

The realization of ultrahigh definition displays necessitates pure-green organic light-emitting diodes (OLEDs) with simultaneously exceptional efficiency, high color purity, and long-term operational stability. Herein, we develop a series of pure-green multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters based on the boron/nitrogen-embedded polycyclic aromatic hydrocarbon (BN-PAH), designed through a rational moderate π-extension and peripheral phenyl blocking strategy. The molecular designs afford narrowband pure-green emission with a full-width at half-maximum (FWHM) of nearly 20 nm and high photoluminescence quantum yields (ΦPLs, up to 95%). By systematically blocking the redox-active positions with phenyl groups, the emitters exhibit significantly enhanced electrochemical and photochemical stability. In bottom-emitting OLEDs, the optimized emitter BN-Tpl-Ph achieves a maximum external quantum efficiency (EQEmax) of 33.8% and long operational lifetime (LT80 = 4012 h at 1000 cd m-2). Notably, in a top-emitting OLED configuration, BN-Tpl-Ph delivers a pure-green emission with a Commission Internationale de l'Eclairage (CIE) y-coordinate of 0.78, a high EQEmax up to 59.2%, and an LT80 of 409 h at 5000 cd m-2. This work reveals the effectiveness of molecular design strategies that combine moderate π-extension with peripheral phenyl blocking for developing high-performance pure-green MR-TADF emitters.

Highly stable and efficient organic light-emitting diodes (OLEDs) with high color purity are critical for ultrahigh-definition display applications. However, achieving these characteristics is hindered by the emitter bandwidth and device stability. Herein, we present the design of tetradentate green Pt(II) emitters with a rigid three-dimensional structure via extended π-conjugation and bulky substituents. This molecular engineering approach effectively suppresses excited-state geometric distortion, resulting in a small full width at half-maximum (FWHM) of 16.4 nanometers in toluene. When the emitters were used in a microcavity-enhanced top-emitting device, the FWHM was further reduced to 14.8 nanometers by controlling constructive and destructive interferences. The top-emitting device showed a Broadcast Service Television 2020 (BT.2020) green color [Commission Internationale de l'Éclairage (CIE): 0.22, 0.75] and a high current efficiency of up to 174 candelas per ampere. Most notably, the device exhibited a record-breaking operational stability, exceeding that of the commercial LED/OLED/MicroLED (micro-light-emitting diode) standard, achieving an unprecedented lifetime to 90% of the initial luminance of 540,100 hours at 1000 candelas per square meter.

While trap states are traditionally considered as performance-limiting defects in organic light-emitting diodes (OLEDs), this work presents a dual-trap exciplex heterojunction system that strategically engineers trap states to enhance device performance. The tailored electron (4CzTPNBu in p-type host) and hole (PO-01 in n-type host) traps are employed for interfacial bidirectional carrier capture synergistically without compromising carrier transport in the exciplex heterojunction system. This innovative design converts interfacial traps into immediate radiative trap-assisted recombination (TAR) centers with significant expansion of exciton recombination zone, simultaneously preventing carrier transport imbalance and charge accumulation. The yellow OLEDs demonstrate cutting-edge 33.9% external quantum efficiency (EQE), and 453.6 h operational lifetime (LT90 at 1000 cd m-2) representing a ninefold enhancement over conventional architectures. Through ideality factor analysis complemented by single-carrier device and transient electroluminescence studies, the fundamental charge transport physics and trap-mediated dynamics are unraveled. Implementation of dual-trap in narrow-band hyperfluorescent systems also enables EQEs surpassing 36% and mitigated efficiency roll-off, along with prolonged LT90 of 178.7 h. The dual-trap methodology successfully merges the advantages for twin emitters and achieves a win-win scenario for efficiency and lifetime, providing a promising paradigm for future high-performance OLED development.

Quantum dot (QD)-based color conversion layers are key components in QD-OLED displays because they can provide high color purity and simplified pixel architectures by converting blue emission from OLEDs into red or green light. The performance of the color conversion layer strongly depends on the blue light absorption, blue leakage, and overall emission efficiency of the display. We fabricated the color conversion layers using a thermally curable polydimethylsiloxane (PDMS) matrix, and their color conversion characteristics were systematically compared with those of QD-only layers. In the QD-only layers, the intensity of the converted green emission increased with increasing QD concentration due to enhanced absorption of blue light emitted from the OLED. However, a large fraction of blue light was transmitted through the layer without being absorbed by the QDs, resulting in a significant blue leakage and a relatively low output/input efficiency below 10%. In contrast, PDMS-based QD color conversion layers exhibited substantially improved color conversion characteristics. By varying the QD concentration and controlling the layer thickness, blue leakage was significantly suppressed and the green emission intensity increased. The maximum color conversion efficiency of 30.0% was obtained at a QD concentration of 8.3 wt% with a layer thickness of 35.9 µm.

Inkjet printing offers a mask-free route to large-area electronics, yet achieving uniformity in micron-scale organic light-emitting diode (µ-OLED) arrays remains challenging. Presented here is a photolithography-free, solvent-programmed, single-step inkjet micro-inlay process in which lateral phase separation self-confines each emissive pixel. Guided by solubility parameters, a trichloromethane (TCM)/1,2-dichloroethane (DCE) binary solvent is designed to optimize interactions among the solvents, emissive solutes, and the poly(4-vinylpyridine) (P4VP) underlayer. Micro-Raman mapping, cross-sectional SEM, and AFM phase analysis support lateral phase separation between the emissive region and the displaced P4VP phase, selective restructuring of P4VP while preserving the underlying transport layer, and no detectable nanoscale phase segregation within the emissive interior, yielding self-confined pixels of approximately 100 µm. High-speed imaging shows that the blend yields reproducible 180 dpi arrays without jetting instability or nonuniform deposition. Green µ-OLED arrays printed with the blend achieve a peak luminance of 2400 cd m-2, a peak current efficiency of 3.5 cd A-1, and a peak external quantum efficiency of 1.0%. The figure of merit and luminance uniformity improve by 2.6- and 6.9-fold, and by 3.9- and 2.9-fold, respectively, relative to neat TCM and neat DCE. This strategy enables scalable fabrication of flexible and three-dimensional conformal OLED platforms.

Due to the difficulty in achieving a suitable match between blue emitters and orange-red thermally activated delayed fluorescence (TADF) polymers, the development of solution-processable white organic light-emitting diodes (OLEDs) based on TADF polymers remains a significant challenge. Herein, a series of orange-red TADF polymers are developed using a strategy involving embedding the acceptor of quinoxaline-6,7-dicarbonitrile (QC) into the backbone and attaching the donor triphenylamine (T) with long alkyl chains as pendants. The synthesized polymers PCzTQCx exhibit orange-red emissions with emission peaks ranging from 571 to 621 nm. Non-doped, solution-processable organic light-emitting diode (OLED) devices based on these polymers exhibit pure white emission with a high color rendering index (CRI) of 80, achieved by using a TADF polymer with a low content of the TQC unit. In addition, warm white emission with a maximum external quantum efficiency (EQEmax) of 14.3%, CRI of 54 and red emission with an EQEmax of 9.3% and an emission peak at 609 nm can also be achieved. Through combination with a blue TADF small-molecule emitter, the single-emissive layer doped devices achieve warm white emission with EQEmax of 15.7%, luminance of 4325 cd m-2, and CRI of 64.

With the rapid development of the next-generation of flexible display technology, high-performance flexible transparent electrodes are urgently required to substitute conventional indium tin oxide (ITO). Herein, we report the fabrication of highly conductive and transparent flexible OLED anodes by embedding Ag NWs into an n-type poly(benzodifurandione):poly(2-ethyl-2-oxazoline) (PBFDO:PEOx) conductive polymer. The optimized Ag NWs/PBFDO:PEOx composite electrode exhibits a low sheet resistance of 15 Ω sq-1 and a high optical transmittance of 90% at 550 nm. Crucially, the n-type PBFDO:PEOx in the composite electrode anchors the silver nanowire network to ensure high conductivity and mechanical stability. Meanwhile, it forms an n-p heterojunction with the p-type hole injection layer (HIL) to enhance carrier injection via tunnelling effects. This structure effectively overcomes the substantial injection barrier caused by work function mismatch. Consequently, the OLED device adopting the Ag NWs/PBFDO:PEOx composite anode delivers a maximum current efficiency of 61.5 cd A-1, which is comparable to that of ITO-based counterparts. Moreover, the composite electrode has significantly better mechanical properties than ITO electrodes, maintaining its electrical conductivity even after 10 000 bending cycles. Therefore, this composite electrode offers an effective alternative to conventional ITO and paves the way for the future development of flexible display technologies.

In this study, we report a scalable and green solid-state synthesis of nitrogen-doped carbon quantum dots (CQDs) from hazelnut shell biomass, using citric acid and urea as carbon and nitrogen sources. Controlled BaCl2 and ZnCl2 doping was applied to tailor nucleation, crystallinity, and surface chemistry. Structural analyses (FTIR, XRD, STEM, XPS, and DLS) revealed that BaCl2-assisted CQDs exhibited higher graphitization, narrower size distribution (7-13 nm), and fewer defects, while ZnCl2-assisted CQDs showed more amorphous and heteroatom-rich surfaces. Optical measurements indicated strong π-π* absorption (≈280 nm), bright blue emission (λem 405-412 nm), and quantum yields of 63.4% (BaCl2) and 50.1% (ZnCl2), with > 95% stability after 30 days. When used as OLED emissive layers, BaCl2-CQDs achieved a luminous efficiency of 0.75 cd A-1, nearly four times that of ZnCl2-CQDs (0.20 cd A-1), despite lower maximum luminance (48.9 vs. 308.1 cd m-2). These results highlight metal ion-assisted nucleation as an effective strategy to engineer CQD properties and enhance device performance, paving the way for sustainable, scalable OLED technologies.

Thermally activated delayed fluorescence (TADF) materials enable nearly 100% internal quantum efficiency in OLEDs, yet the substituent-dependent regulation of excited states in boron-based acceptors remains insufficiently clarified. In this study, we theoretically investigate the blue boron-based TADF emitter BOBT and five of its derivatives (B1-B5) bearing electron-withdrawing groups (-F, -Cl, -CN, -COOH, -COOCH3), to clarify how acceptor engineering influences charge transfer, singlet-triplet separation, and exciton-conversion dynamics. The analysis shows that systematic substitution effectively tunes donor-acceptor decoupling, frontier orbital gaps, ΔE ST, and oscillator strengths. Among the substituted derivatives, B5 presents the most balanced excited-state profile, combining a reduced bandgap, a relatively small ΔE ST of 0.106 eV, and appreciable S1-T1/T2 spin-orbit coupling. These results indicate that targeted acceptor engineering can effectively regulate excited-state energetics and spin mixing in blue TADF materials, although the present calculations do not allow a definitive conclusion that the RISC rate is enhanced relative to the parent molecule B.

The self-assembly of π-conjugated molecules into supramolecular columnar structures has become an effective strategy for the creation of soft, durable, and adaptable materials with immense potential for application in organic optoelectronic devices. In this regard, the columnar organization of discotic liquid crystals (DLCs) is well-studied in terms of a quasi-1D charge transport medium, which can be exploited across a range of organic electronic device applications. There are relatively few examples of room temperature columnar DLCs emitting thermally activated delayed fluorescent (TADF). Herein, we demonstrate a molecular design strategy to deliver a material that simultaneously shows bright and efficient TADF and self-organizes into columnar DLCs at room temperature. The compound TCzTRZ-DLC contains three dendrimeric carbazole-based donors with mesogenic units decorating a central 1,3,5-triphenyltriazine acceptor. Notably, the system exhibited a desired homeotropic alignment resulting in preferential aromatic π-stacking among disc-like molecules, which is beneficial to boost the light out-coupling efficiency in solution-processed organic light-emitting diodes (OLEDs). The resulting green-emitting SP-OLEDs emitted at λ EL of 488 nm and showed a maximum external quantum efficiency, EQEmax of 15.5%. This represents a significant improvement in OLED efficiency compared to other solution-processed devices using TADF emitters bearing mesogenic groups.

We report an ortho-B-π-B strategy enabling a long-wavelength MR-TADF material with suppressed molecular vibrations. The emitter QuBN shows yellow emission at 552 nm with 20 nm FWHM and 91% quantum yield. Its OLED achieves an external quantum efficiency of 27.9%, which is boosted to 31.3% with reduced roll-off via phosphorescence sensitization.

Organic semiconductors are attractive for the development of flexible, wavelength-tunable lasers. However, most reported organic micro/nanolasers rely on femtosecond-pulsed optical pumping, which is impractical for real-world applications. This limitation has urged the pursuit of electrically pumped organic lasers; yet their realization remains a long-standing challenge primarily due to a fundamental materials dilemma, in which high-gain organic semiconductors often suffer from poor, unbalanced charge transport. Here, we demonstrate that this intrinsic trade-off can be effectively alleviated through a molecular doping strategy. Employing a high-gain spirofluorene derivative as the emissive layer, we introduce an n-type doped layer to construct an organic light-emitting diode (OLED), achieving more balanced charge transport while preserving outstanding optical gain. Consequently, singlet-polaron annihilation is significantly suppressed, as evidenced by reduced efficiency roll-off and electrically pumped transient absorption measurements. When integrated with a distributed feedback (DFB) resonator, the resulting device exhibits ultra-narrow (∼2 nm) electroluminescence under pulsed current injections and delivers low-threshold nanosecond lasing under an optical-electrical co-pumping configuration, thereby demonstrating a practical architecture for implementing organic laser diodes. Our work provides a general strategy to overcome the intrinsic paradox where high-gain organic semiconductors struggle to maintain balanced charge transport, illuminating a pathway toward light amplification under electrical excitation.