Integrating Asymmetric O−B−N Unit in Multi‐Resonance Thermally Activated Delayed Fluorescence Emitters towards High‐Performance Deep‐Blue Organic Light‐Emitting Diodes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(18)

Published: March 3, 2023

Developing deep-blue thermally activated delayed fluorescence (TADF) emitters with both high efficiency and color purity remains a formidable challenge. Here, we proposed design strategy by integrating asymmetric oxygen-boron-nitrogen (O-B-N) multi-resonance (MR) unit into traditional N-B-N MR molecules to form rigid extended O-B-N-B-N π-skeleton. Three MR-TADF of OBN, NBN ODBN featuring O-B-N, symmetric units were synthesized through the regioselective one-shot electrophilic C-H borylation at different positions same precursor. The proof-of-concept emitter exhibited respectable emission Commission International de l'Eclairage coordinate (0.16, 0.03), photoluminescence quantum yield 93 % narrow full width half maximum 26 nm in toluene. Impressively, simple trilayer OLED employing as achieved external up 24.15 accompanied deep blue corresponding CIE y below 0.1.

Language: Английский

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One-Shot Construction of BN-Embedded Heptadecacene Framework Exhibiting Ultra-narrowband Green Thermally Activated Delayed Fluorescence

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(21), P. 11504 - 11511

Published: May 16, 2023

BN-embedded nonacene, tridecacene, and heptadecacene frameworks were constructed using one-shot quadruple, sextuple, octuple borylation reactions, respectively. The key to success is the judicious choice of borylating reagents long-chain alkyl-substituted carbazolyl groups as boron-trapping groups, which suppressed decrease in HOMO energy insolubilization associated with borylation. Based on product yields, each electrophilic C-H proceeded >99% yield, best efficiency reported so far for reactions. Owing multiple resonance effects boron nitrogen, prepared acenes exhibited ultra-narrowband green thermally activated delayed fluorescence full-width at half-maximum 12-16 nm; moreover, their kRISC values order 105 s-1. We fabricated an organic light-emitting diode by employing nonacene emitter, high external quantum (EQE) 28.7%. device also showed a minimum roll-off EQE 25.8% 1000 cd m-2.

Language: Английский

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RGB Thermally Activated Delayed Fluorescence Emitters for Organic Light‐Emitting Diodes toward Realizing the BT.2020 Standard

Advanced Science, Journal Year: 2023, Volume and Issue: 10(28)

Published: Aug. 16, 2023

Abstract With the surging demand for ultra‐high‐resolution displays, International Telecommunication Union (ITU) announce next‐generation color gamut standard, named ITU‐R Recommendation BT.2020, which not only sets a seductive but challenging milestone display technologies also urges researchers to recognize importance of coordinates. Organic light‐emitting diodes (OLEDs) are an important technology in current daily life, they face challenges approaching BT.2020 standard. Thermally activated delayed fluorescence (TADF) emitters have bright prospects OLEDs because possess 100% theoretical exciton utilization. Thus, development TADF emitting primary red (R), green and blue (B) emission is great significance. Here, comprehensive overview latest advancements that exhibit Commission Internationale de l'Éclairage (CIE) coordinates surpassing National Television System Committee (NTSC) standards presented. Rational strategies molecular designs, as well resulting photophysical properties OLED performances, discussed elucidate underlying mechanisms shifting CIE both donor‐acceptor multiple resonance (MR) typed toward Finally, realization wide‐color‐gamut standard this research area provided.

Language: Английский

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Deep‐Blue Narrowband Hetero[6]helicenes Showing Circularly Polarized Thermally Activated Delayed Fluorescence Toward High‐Performance OLEDs

Advanced Materials, Journal Year: 2023, Volume and Issue: 36(1)

Published: Nov. 14, 2023

Abstract Helicenes exhibit substantial potential as circularly polarized luminescence (CPL) active molecules. However, their application in organic light‐emitting diodes (CP‐OLEDs) is typically hindered by the challenge of integrating both high color purity and efficient triplet‐harvesting capability, particularly blue spectral region. Herein, a series hetero[6]helicene‐based emitters that strategically engineered through helical extension deep‐blue double‐boron‐based multiple resonance thermally activated delayed fluorescence (MR‐TADF) motif, introduced. Importantly, does not cause apparent structural deformation or perturb frontier molecular orbitals; thus, preserving emission MR‐TADF characteristics parent molecule. This approach also leads to reduced reorganization energy, resulting with narrower linewidth higher photoluminescence quantum yield. Further, motif enhances racemization barrier improved CPL performance dissymmetry factor values up 1.5 × 10 −3 . Exploiting these merits, devices incorporating chiral dopants demonstrate within Broadcast Service Television 2020 color‐gamut range, record external efficiencies (EQEs) 29.3%, have distinctive electroluminescence (CPEL) signals. Overall, authors’ findings underscore promising strategy for designing narrowband chiroptical materials advancing high‐definition displays.

Language: Английский

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Color‐Tunable Dual‐Mode Organic Afterglow for White‐Light Emission and Information Encryption Based on Carbazole Doping

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(45)

Published: Sept. 20, 2023

Dual-mode emission materials, combining phosphorescence and delayed fluorescence, offer promising opportunities for white-light afterglow. However, the fluorescence lifetime is usually significantly shorter than that of phosphorescence, limiting duration emission. In this study, a carbazole-based host-guest system can be activated by both ultraviolet (UV) visible light reported to achieve balanced resulting in long-lived Our study demonstrated critical role charge transfer state afterglow mechanism, where separation recombination process directly determined Simultaneously, an efficient reversed intersystem crossing was obtained between singlet triplet states, which facilitating properties system. As result, successfully prolonged approach phosphorescence. This work presents improvement strategy via doping method realize durable

Language: Английский

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A Simple Molecular Design Strategy for Pure‐Red Multiple Resonance Emitters

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(20)

Published: March 15, 2023

Though the flourishment of materials with multiple resonance (MR) in blue to green regions, red-emissive MR emitters are still rare literatures, which definitely should be resolved for further applications. Herein, we report a simple molecular design strategy construction pure-red by conjugate charge transfer, could greatly enhance π-conjugation degree and charge-transfer property target molecule while maintaining basic feature MR, leading significant redshift more than 128 nm compared selected parent core. The proof-of-concept emitter PPZ-BN exhibited emission dominant peak at 613 small full-width-at-half-maximum 0.16 eV (48 nm). optimized organic light-emitting diode showed high external quantum efficiency 26.9 %, roll-off, an excellent operation stability (LT99) 43 hours initial luminance 10 000 cd m-2 .

Language: Английский

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Improving the stability and color purity of a BT.2020 blue multiresonance emitter by alleviating hydrogen repulsion

Science Advances, Journal Year: 2023, Volume and Issue: 9(19)

Published: May 12, 2023

Stable deep blue multiresonance emitters with small full width at half maximum (FWHM) are attractive for wide color-gamut organic light-emitting diodes (OLEDs). However, the steric repulsion from spatially close hydrogens would twist skeletons, causing spectral broadening and molecular instability issues. Here, we strategically introduce a mesitylboron locking unit into carbazole-embedded model emitter, alleviating hydrogen repulsions also strengthening para-positioned weak carbon-nitrogen bond in anionic states. An emission peaking 452 nm an FWHM of merely 14 nearly BT.2020 chromaticity coordinates obtained toluene, affording high external quantum efficiency 33.9% sensitizing device. Moreover, impressive LT97 (time to decay 97% initial luminance) 178 hours constant current density 12 mA/cm2 was achieved stable device y coordinate 0.057, 20 times longer than emitter even substantially red-shifted emission.

Language: Английский

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Multi‐Resonance Building‐Block‐Based Electroluminescent Material: Lengthening Emission Maximum and Shortening Delayed Fluorescence Lifetime

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(27)

Published: April 29, 2023

Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials are considered a class of organic with exceptional electronic and optical properties, which make them promising for the applications in light-emitting diodes (OLEDs). In this study, we improved, synthesized, characterized multiple-resonance type emitter based on assembly MR-building blocks (MR-BBs). By optimizing geometric arrangement MR-BBs, were able to generate narrowband emission longer wavelength region shorten excited-state lifetime, resulting improved efficiency compared parent molecule. Our proof-of-concept molecule, m-DBCz, exhibited yellowish-green TADF full width at half-maximum 32 nm small singlet-triplet energy gap 0.04 eV. The OLED developed using m-DBCz as demonstrated electroluminescence 548 achieved high external quantum (EQE) 34.9 %. Further optimization device resulted 36.3 % extremely low roll-off, EQE values 30.1 27.7 obtained even luminance levels 50 000 100 cd m-2 . These results demonstrate potential MR-TADF ultrahigh-luminance OLEDs.

Language: Английский

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A figure of merit for efficiency roll-off in TADF-based organic LEDs

Nature, Journal Year: 2024, Volume and Issue: 627(8005), P. 747 - 753

Published: March 27, 2024

Abstract Organic light-emitting diodes (OLEDs) are a revolutionary display technology that has been successfully commercialized in mobile phones and televisions 1,2 . The injected charges form both singlet triplet excitons, for high efficiency it is important to enable triplets as well singlets emit light. At present, materials harvest by thermally activated delayed fluorescence (TADF) very active field of research an alternative phosphorescent emitters usually use heavy metal atoms 3,4 Although excellent progress made, most TADF OLEDs there severe decrease the drive current increased, known roll-off. So far, much literature suggests roll-off should be reduced minimizing energy difference between excited states (Δ E ST ) maximize rate conversion means reverse intersystem crossing ( k RISC 5–20 We analyse wide range find neither these parameters fully accounts reported By considering dynamic equilibrium materials, we propose figure merit design reduce discuss its correlation with data OLEDs. Our new will guide development can It help improve at realistic operating conditions expand applications require brightness, such lighting, augmented reality lasing.

Language: Английский

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Deep-blue organic light-emitting diodes for ultrahigh-definition displays

Nature Photonics, Journal Year: 2024, Volume and Issue: 18(11), P. 1161 - 1169

Published: Aug. 19, 2024

Language: Английский

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