Narrowband Emissive Thermally Activated Delayed Fluorescence Materials

Advanced Optical Materials, Journal Year: 2022, Volume and Issue: 10(22)

Published: Sept. 23, 2022

Abstract Organic thermally activated delayed fluorescence (TADF) materials have attracted significant research interest in the field of organic electronics because their inherent advantage 100% exciton utilization capability light‐emitting diodes (OLEDs) without use noble metals. However, despite high internal electroluminescence quantum efficiencies approaching unity, broad emission spectra with sizable full width at half maxima (FWHM; 60–100 nm) present a critical issue that must be solved for application ultrahigh‐definition OLED displays. Recently, new paradigm TADF featuring multiple resonance (MR) effect based on heteroatom‐doped polycyclic aromatic frameworks, referred to as MR‐TADF materials, has emerged and garnered considerable owing remarkable features efficient narrowband emissions extremely small FWHMs (≤30 nm). Currently, occupy prominent position cutting‐edge from both chemical physical perspectives. This review article focuses recent progress emissive systems perspective molecular design, photophysical properties, performance OLEDs. The current status future prospects this advanced material technology are discussed comprehensively.

Language: Английский

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Ultrapure green organic light-emitting diodes based on highly distorted fused π-conjugated molecular design

Nature Photonics, Journal Year: 2023, Volume and Issue: 17(3), P. 280 - 285

Published: Jan. 9, 2023

Language: Английский

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Sterically Wrapped Multiple Resonance Fluorophors for Suppression of Concentration Quenching and Spectrum Broadening

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 61(2)

Published: Oct. 12, 2021

Multiple resonance (MR) emitters are promising for highly efficient organic light-emitting diodes (OLEDs) with narrowband emission; however, they still face intractable challenges concentration-caused emission quenching, exciton annihilation, and spectral broadening. In this study, sterically wrapped MR dopants a fluorescent core sandwiched by bulk substituents were developed to address the reducing intermolecular interactions. Consequently, high photo-luminance quantum yields of ≥90 % small full width at half maximums (FWHMs) ≤25 nm over wide range dopant concentrations (1-20 wt %) recorded. addition, we demonstrated that emitter can effectively suppress Dexter interaction when doped in thermally activated delayed fluorescence sensitizer, eliminating loss through triplet. Within above concentration range, optimal realizes remarkably maximum external efficiencies 36.3-37.2 %, identical FWHMs 24 nm, alleviated efficiency roll-offs OLEDs.

Language: Английский

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Realizing Record‐High Electroluminescence Efficiency of 31.5 % for Red Thermally Activated Delayed Fluorescence Molecules

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(44), P. 23635 - 23640

Published: Aug. 30, 2021

Tailor-made red thermally activated delayed fluorescence (TADF) molecules comprised of an electron-withdrawing pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile core and various electron-donating triarylamines are developed. They can form intramolecular hydrogen-bonding, which is conducive to improving emission efficiency promoting horizontal orientation show near infrared (NIR) emissions (692-710 nm) in neat films (606-630 with high photoluminescence quantum yields (73-90%) doped films. prefer large dipole ratios films, rendering optical out-coupling factors (0.39-0.41). Their non-doped OLEDs exhibit NIR lights (716-748 maximum external efficiencies (ηext,max ) 1.0-1.9%. And their radiate (606-648 achieve record-beating ηext,max up 31.5%. These new TADF materials should have great potentials display lighting devices.

Language: Английский

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Fusion of Multi‐Resonance Fragment with Conventional Polycyclic Aromatic Hydrocarbon for Nearly BT.2020 Green Emission

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(24)

Published: April 1, 2022

Herein, we report a general strategy for achieving ultra-pure green emissions by suppressing the shoulder peaks in emission spectra of conventional polycyclic aromatic hydrocarbons (PAHs). Through precise synthetic fusion multi-resonance (MR) fragments with PAH, extended π-conjugation lengths, increased molecular rigidity, and reduced vibrational frequency could be simultaneously realized. The proof-of-concept emitters exhibited dominant at ca. 521 nm, photoluminescence quantum yields that are greater than 99 %, small full-width-at-half-maximum 23 CIE coordinates (0.16, 0.77). bottom-emitting organic light-emitting diode (OLED) record-high CIEy value 0.74 high maximum external efficiency 30.5 %. top-emitting OLED not only achieved BT.2020 color (CIE: 0.17, 0.78) first time but also showed superior performance among all devices, current 220 cd A- .

Language: Английский

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Highly Efficient Asymmetric Multiple Resonance Thermally Activated Delayed Fluorescence Emitter with EQE of 32.8 % and Extremely Low Efficiency Roll‐Off

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(14)

Published: Feb. 1, 2022

Multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters show great potentials for high color purity organic light-emitting diodes (OLEDs). However, the simultaneous realization of photoluminescence quantum yield (PLQY) and reverse intersystem crossing rate (kRISC ) is still a formidable challenge. Herein, novel asymmetric MR-TADF emitter (2Cz-PTZ-BN) designed that fully inherits PLQY large kRISC values properly selected parent molecules. The resonating extended π-skeleton with peripheral protection can achieve 96 % fast above 1.0×105 s-1 , boost performance corresponding pure green devices an outstanding external efficiency (EQE) up to 32.8 without utilizing any sensitizing hosts. Remarkably, device sufficiently maintains EQE exceeding 23 at luminance 1000 cd m-2 representing highest value reported materials same luminescence.

Language: Английский

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Purely Spin‐Vibronic Coupling Assisted Triplet to Singlet Up‐Conversion for Real Deep Blue Organic Light‐Emitting Diodes with Over 20% Efficiency and y Color Coordinate of 0.05

Advanced Science, Journal Year: 2021, Volume and Issue: 8(20)

Published: Aug. 13, 2021

Finding narrow-band, ultrapure blue thermally activated delayed fluorescence (TADF) materials is extremely important for developing highly efficient organic light-emitting diodes (OLEDs). Here, spin-vibronic coupling (SVC)-assisted emitters obtained by joining two carbazole-derived moieties at a para position of phenyl unit and performing substitutions using several blocking groups are presented. Despite relatively large singlet-triplet gap (∆EST ) >0.2 eV, triplet-to-singlet crossover can be realized, with assistance from resonant SVC. To enhance the spin crossover, electronic energy levels fine-tuned, thereby causing ∆EST to in resonance triplet-triplet (∆ETT ). A sizable population transfer between multiplicities (>103 s-1 achieved, this result agrees well theoretical predictions. An OLED fabricated multiple-resonance-type SVC-TADF emitter CIE color coordinates (0.15, 0.05) exhibits emissions, narrow full-width-at-half-maximum 21 nm high external quantum efficiency 23.1%.

Language: Английский

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Multiple‐Resonance‐Induced Thermally Activated Delayed Fluorescence Materials Based on Indolo[3,2,1‐jk]carbazole with an Efficient Narrowband Pure‐Green Electroluminescence

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(41)

Published: Aug. 19, 2022

Herein, we report two multiple-resonance thermally activated delayed fluorescence emitters (VTCzBN and TCz-VTCzBN) based on indolo[3,2,1-jk]carbazole unit boron-nitrogen skeletons, whose emissions peaking at 496 521 nm with full width half maximum of 34 29 nm, respectively. Meanwhile, fast rate constants reverse intersystem crossing above 106 s-1 are obtained due to small singlet-triplet energy gaps large spin-orbital coupling values. Notably, planar molecular structures along the transition dipole moment direction endow them high horizontal emitting ratios up 94 %. Consequently, corresponding organic light-emitting diodes (OLEDs) show external quantum efficiencies 31.7 % 32.2 %, Particularly, OLED TCz-VTCzBN display ultra-pure green emission Commission Internationale de l'Eclairage coordinates (0.22, 0.71), consistent standard National Television System Committee.

Language: Английский

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Realizing efficient blue and deep-blue delayed fluorescence materials with record-beating electroluminescence efficiencies of 43.4%

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: April 10, 2023

As promising luminescent materials for organic light-emitting diodes (OLEDs), thermally activated delayed fluorescence are booming vigorously in recent years, but robust blue ones still remain challenging. Herein, we report three highly efficient and deep-blue comprised of a weak electron acceptor chromeno[3,2-c]carbazol-8(5H)-one with rigid polycyclic structure donor spiro[acridine-9,9'-xanthene]. They hold distinguished merits excellent photoluminescence quantum yields (99%), ultrahigh horizontal transition dipole ratios (93.6%), fast radiative reverse intersystem crossing, which furnish superb electroluminescence Commission Internationale de I'Eclairage coordinates (CIEx,y) (0.14, 0.18) 0.15) record-beating external efficiencies (ηexts) 43.4% 41.3%, respectively. Their efficiency roll-offs successfully reduced by suppressing triplet-triplet singlet-singlet annihilations. Moreover, high-performance green hyperfluorescence OLEDs achieved utilizing these as sensitizers multi-resonance dopants, providing state-of-the-art ηexts 32.5% (CIEx,y = 0.14, 0.10) 37.6% 0.32, 0.64), respectively, well greatly advanced operational lifetimes. These splendid results can surely inspire the development devices.

Language: Английский

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Sequential Multiple Borylation Toward an Ultrapure Green Thermally Activated Delayed Fluorescence Material

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 145(3), P. 1505 - 1511

Published: Dec. 22, 2022

Multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters have emerged as an important component of organic light-emitting diodes (OLEDs) because their narrowband emission and high exciton utilization efficiency. However, the chemical space MR-TADF remains mostly unexplored lack suitable synthetic protocols. Herein, we demonstrate a sequential multiple borylation reaction that provides new synthetically accessible space. ω-DABNA, proof-of-concept material, exhibited green TADF with full width at half-maximum 22 nm small singlet-triplet energy gap 13 meV. The OLED employing it emitter electroluminescence 512 nm, Commission International de l'Éclairage coordinates (0.13, 0.73) external quantum efficiency (EQE) 31.1%. Moreover, device showed minimum roll-off, EQE 29.4% 1000 cd m-2.

Language: Английский

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