Efficient Deep‐Blue Multiple‐Resonance Emitters Based on Azepine‐Decorated ν‐DABNA for CIE_y below 0.06

Advanced Materials, Год журнала: 2024, Номер 36(30)

Опубликована: Май 2, 2024

Abstract Ultrapure deep‐blue emitters are in high demand for organic light‐emitting diodes (OLEDs). Although color coordinates serve as straightforward parameters assessing purity, precise control over the maximum wavelength and full‐width at half‐maximum is necessary to optimize OLED performance, including luminance efficiency luminous efficacy. Multiple‐resonance (MR) promising candidates achieving ideal luminescence properties; consequently, a wide variety of MR frameworks have been developed. However, most these experience displacement from color, which limits their practical applicability. Therefore, molecular design that compatible with modulating energy levels output particularly valuable. Here, it demonstrated azepine donor unit induces an appropriate blue‐shift emission while maintaining efficient characteristics, photoluminescence quantum yield, narrow emission, fast reverse intersystem crossing rate. OLEDs using newly developed based on ν ‐DABNA framework simultaneously exhibit ≈30%, efficacy ≈20 lm W −1 , exceptional purity Commission Internationale de l’Éclairage low (0.14, 0.06), notably operational stability. These results demonstrate unprecedentedly compared those observed previously reported emitters.

Язык: Английский

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Stepwise Toward Pure Blue Organic Light‐Emitting Diodes by Synergetically Locking and Shielding Carbonyl/Nitrogen‐Based MR‐TADF Emitters

Advanced Science, Год журнала: 2024, Номер 11(28)

Опубликована: Май 5, 2024

Deep-blue multi-resonance (MR) emitters with stable and narrow full-width-at-half-maximum (FWHM) are of great importance for widening the color gamut organic light-emitting diodes (OLEDs). However, most planar MR vulnerable to intermolecular interactions from both host guest, causing spectral broadening exciton quenching in thin films. Their emission solid state is environmentally sensitive, purity often inferior that solutions. Herein, a molecular design strategy presented simultaneously narrows FWHM suppresses by combining intramolecular locking peripheral shielding within carbonyl/nitrogen-based core. Intramolecularly bears narrower 2,10-dimethyl-12,12-diphenyl-4H-benzo[9,1]quinolizino[3,4,5,6,7-defg]acridine-4,8(12H)-dione solution further peripheral-shielding groups, deep-blue emitter (12,12-diphenyl-2,10-bis(9-phenyl-9H-fluoren-9-yl)-4H-benzo[9,1]quinolizino[3,4,5,6,7-defg]acridine-4,8(12H)-dione, DPQAO-F) exhibits ultra-pure (c.a., 24 nm) minimal variations (∆FWHM ≤ 3 films over wide doping range. An OLED based on DPQAO-F presents maximum external quantum efficiency (EQE

Язык: Английский

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Stable pure-green organic light-emitting diodes toward Rec.2020 standard

Nature Communications, Год журнала: 2024, Номер 15(1)

Опубликована: Май 23, 2024

Abstract Manipulating dynamic behaviours of charge carriers and excitons in organic light-emitting diodes (OLEDs) is essential to simultaneously achieve high colour purity superior operational lifetime. In this work, a comprehensive transient electroluminescence investigation reveals that incorporating thermally activated delayed fluorescence assistant molecule with deep lowest unoccupied molecular orbital into bipolar host matrix effectively traps the injected electrons. Meanwhile, hole injection transport are still dominantly governed by molecules. Thus, recombination zone notably shifts toward interface between emissive layer (EML) electron-transporting (ETL). To mitigate interfacial carrier accumulation exciton quenching, could serve as non-barrier functional spacer EML/ETL, enabling distribution away from interface. Consequently, optimized OLED exhibits low driving voltage, promising device stability (95% initial luminance 1000 cd m −2 , LT 95 > 430 h), Commission Internationale de L’Éclairage y coordinate 0.69. This indicates managing through rational energy level alignment holds potential for satisfying Rec.2020 standard achieving commercial-level stability.

Язык: Английский

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Narrow Band Organic Emitter for Pure Green Solution‐Processed Electroluminescent Devices with CIE Coordinate y of 0.77

Advanced Optical Materials, Год журнала: 2024, Номер 12(21)

Опубликована: Апрель 9, 2024

Abstract While the development of solution‐processed organic light‐emitting diodes (sOLEDs) utilizing multiple resonance‐induced thermally activated delayed fluorescence (MR‐TADF) is highly significant, it restricted by limited solubility and film‐forming property resulting from rigid conjugate planarity MR‐TADF materials. Herein, an effective strategy presented to obtain narrowband emitters introducing inert steric bulky hindrance group into resonance skeleton, thereby mitigating issues arising intermolecular packing‐induced poor solution processing ability quenching effects. The target emitter, designed as 3CzSF‐BN, exhibits pure‐green emission with a peak at 520 nm small full width half maximum (FWHM) 30 (0.14) eV. Remarkably, achieves exceptional photoluminescence quantum yield (PLQY) 100% notable advancements in attributes. optimized bottom‐emitting sOLED (BE‐sOLED) device external efficiency (EQE) over 20% Commission Internationale de I’Éclairage (CIE) coordinates (0.214, 0.716). Notably, top‐emitting (TE‐sOLED) ultra‐pure green color FWHM 22 CIE (0.138, 0.771), highlighting effectiveness this designing high‐performance

Язык: Английский

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Hyperconjugation Engineering of π-Extended Azaphosphinines for Designing Tunable Thermally Activated Delayed Fluorescence Emitters

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Янв. 20, 2025

Implanting heteroatoms into organic π-conjugated molecules (OCMS) offered a great opportunity to fine-tune the chemical structures and optoelectronic properties. This work describes new family of 1,4-azaphosphinines with extended σ–π hyperconjugations. The photophysical studies revealed that azaphosphinines exhibited narrow-band thermally activated delayed fluorescence (TADF) ( full width at half-maximum: 26–40 nm). According orbital localization analysis natural bond analysis, effective σ*−π* hyperconjugation is believed induce multiple-resonance (MR) TADF, which distinct from p−π conjugation-induced MR-TADF in BN systems. Although having large ΔES1–T1s (>3.0 ev), study suggested σ*−π endowed system structural vibration favorable for spin-vibronic-assisted RISC. Having tunable p-centers (lp, O, S, Se, Me+), showed fine-tuned TADF. Generally, strong hyperconjugations small ΔES1–T1s, efficient RISCs, high PLQYs. Leveraging on hyperconjugations, TADF emission spanned UV-blue green. Particularly, photoluminescence quantum yields (74% toluene 92% 10% doped PMMA). As proof concept, two PO center were applied as light-emitting materials lighting-emitting diodes. devices UV- deep-blue EQE 10.3%. current us strategy, namely, hyperconjugation-induced MR-TADF, designing OCMs

Язык: Английский

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Bifunctional Group Modulation Strategy Enables MR‐TADF Electroluminescence Toward BT.2020 Green Light Standard

Advanced Materials, Год журнала: 2025, Номер unknown

Опубликована: Янв. 23, 2025

Abstract Herein, a parallel “bifunctional group” modulation method is proposed to achieve controlled of the emission wavelength and full‐width at half‐maximum (FWHM) values. As result, three proof‐of‐concept emitters, namely DBNDS‐TPh, DBNDS‐DFPh, DBNDS‐CNPh, are designed synthesized, with first functional dibenzo[ b,d ]thiophene unit concurrently reducing bandgap elevate their triplet state energy. A second group 1 , ′: 3 ′, ″‐ triphenyl electron acceptors 1,3‐difluorobenzene benzonitrile respectively, deepen HOMO LUMO levels. Accordingly, CIE coordinates DBNDS‐CNPh (0.13, 0.77), (0.14, 0.76) in dilute toluene solution. This marks instance achieving y value 0.77 solutions. Significantly, non‐sensitized pure‐green OLEDs based on DBNDS‐TPh DBNDS‐DFPh demonstrate peak EQE 35.0% 34.5%, corresponding (0.18, 0.75), (0.17, doping concentration wt.%, representing green OLED reaching 0.76 bottom‐emitting device structure as reported literature.

Язык: Английский

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Isomeric Pentagonal Fusion and π‐Expanding of Nitrogen/Carbonyl‐Containing Multi‐Resonant Emitters for High‐Performance and Narrowband Organic Electroluminescence

Advanced Functional Materials, Год журнала: 2025, Номер unknown

Опубликована: Фев. 26, 2025

Abstract Embedding nitrogen/carbonyl (N/C═O) units into rigid heterocyclic aromatic hydrocarbons creates novel multi‐resonant thermally activated delayed fluorescence (MR‐TADF) molecules. Nevertheless, the intrinsic short‐range charge transfer (SRCT) characteristics of N/C═O derivatives, as exemplified by quinolino[3,2,1‐ de ]acridine‐5,9‐dione (QAO), result in broad spectral bandwidths, posing challenging for achieving deep blue emission. Herein, a pentagonal cyclization and isomeric expansion strategy aimed is proposed at modulating SRCT characters molecular symmetry to further narrow bandwidths regulate excited‐state energy levels. By fusing two 8 H ‐indolo[3,2,1‐ ]acridin‐8‐one (IAO) skeletons via central phenyl segment that cyclizes nitrogen atoms, proof‐of‐concept emitters with reduced widths are developed. These achieved wide color tuning range from (439 nm) pure green (520 exhibited 17–24 nm (≈0.11 eV). The corresponding electroluminescence devices demonstrated bright deep‐blue, blue, emissions linewidths. Notably, sensitized deep‐blue/blue incorporating mTIAO pTIAO exceptional external quantum efficiencies 29.6% 34.4%, respectively, representing most efficient blue‐light derivatives reported date. Furthermore, index mTIAO, measured (0.147, 0.063), aligns perfectly National Television System Committee standard (0.15, 0.06).

Язык: Английский

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Luminescent Organosilane and Organogermane MR‐TADF Emitters for Operationally Stable Blue Organic Light‐Emitting Diodes

Advanced Optical Materials, Год журнала: 2025, Номер unknown

Опубликована: Янв. 10, 2025

Abstract Improving operational stability for organic light‐emitting diode (OLED) is a hotspot in scientific research. It proposed that silicon (Si) and germanium (Ge) can exhibit hyperconjugation effects participate conjugated systems, thereby stabilizing molecules’ excited polarized states. Herein, the importance of incorporating Si Ge multi‐resonance thermally activated delayed fluorescence emitters revealed to improve their luminescence efficiency intrinsic stability. Computational studies show introducing atoms strengthen C−Si C−Ge bonds due effect, resulting higher bond dissociation energies molecular photostability. With efficient spin‐vibronic coupling spin‐orbital coupling, flexible conformations facilitate spin‐flip processes by enriching characters density A maximum external quantum 30.0% BN ‐Ge ‐based blue‐emitting OLEDs, with (Commission Internationale de l'Eclairage) CIE y ≤ 0.18 realized. In particular, LT 90 at 1000 cd m −2 48.3 7.1 h achieved BN‐Si BN‐Ge respectively, using developed deuterated SiCzCz‐d 15 SiTriCz2‐d 16 as hole‐transporting host materials. anticipated study will provide insights into design group IV element‐containing multiple‐resonance fluorescent optoelectronics applications.

Язык: Английский

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Pressure‐Induced Emission Enhancement of Multi‐Resonance o‐Carborane Derivatives via Exciton‒Vibration Coupling Suppression

Advanced Science, Год журнала: 2025, Номер unknown

Опубликована: Янв. 27, 2025

Abstract Polycyclic multiple resonance (MR) molecules reveal narrowband emission, making them very promising emitters for high color purity display. Nevertheless, they still have challenges such as aggregation‐induced emission quenching and spectral broadening. Overcoming these obstacles requires an in‐depth understanding of the correlations among alterations in their geometries, packing structures, molecular vibrations corresponding changes photoluminescence (PL) properties. Herein, it is demonstrated that high‐pressure infrared, UV−visible absorption, fluorescence spectroscopies can be combined with computational results to elucidate influence subtle structural variations on exciton‒vibration couplings PL An ortho‐carborane‐decorated MR emitter (BNC) a piezochromic molecule exhibits enhancement under pressure. A thorough analysis situ experimental measurements calculated reveals pressure‐induced exciton binding energy are responsible unusual piezochromism. This research provides insights into structure‒fluorescence relationship potential techniques optimize materials advanced organic light‐emitting diodes (OLEDs) applications.

Язык: Английский

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Carbonyl‐ and Nitrogen‐Embedded Multi‐Resonance Emitter with Ultra‐Pure Green Emission and High Electroluminescence Efficiencies

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(4)

Опубликована: Дек. 8, 2023

Abstract Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters with narrow emission spectra have garnered significant attention in future organic light‐emitting diode (OLED) displays. However, current C=O/N‐embedded MR‐TADF systems still lack satisfactory performance terms of electroluminescence bandwidths and external quantum efficiencies (EQEs). In this study, a green emitter, featuring two acridone units incorporated sterically protected 11‐ring fused core skeleton, is successfully synthesized through finely controlling the reaction selectivity. The superior combination multiple intramolecular fusion steric wrapping strategies design emitter not only imparts an extremely spectrum high yield to but also mitigates aggregation‐induced spectral broadening quenching. Therefore, exhibits leading OLED among C=O/N‐based systems, achieving EQE up 37.2 %, full width at half maximum merely 0.11 eV (24 nm), Commission Internationale de l′Éclairage coordinate (0.20, 0.73). This study marks advance realization ideal holds profound implications for synthesis other systems.

Язык: Английский

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