Achieving Efficient Narrow-Spectrum Violet Organic Light-Emitting Diodes Based on Through-Space Charge Transfer Molecules

ACS Materials Letters, Journal Year: 2025, Volume and Issue: unknown, P. 457 - 464

Published: Jan. 3, 2025

Violet organic light-emitting diodes (OLEDs) hold promise for advanced applications, yet achieving simultaneously high efficiency and color purity remains challenging. This study presents a rational design of violet emitters by establishing through-space charge transfer (TSCT) framework that enhances high-level reverse intersystem crossing (hRISC) the effective utilization triplet excitons. Two TSCT emitters, BO-MX-ICz tBO-MX-ICz, are tailored with weak donor acceptor bridged 9,9-dimethylxanthene in face-to-face stacking arrangement. These show narrow photoluminescence (PL) efficiency. Their OLEDs exhibit high-color-purity electroluminescence (EL) peaks at 406 408 nm, full width half-maximum (fwhm) 25 maximum external quantum efficiencies (ηext,maxs) 4.61% 5.03%. Additionally, as hosts green multiresonance (MR) they deliver EL spectra excellent ηext,maxs up to 34.36%. molecular strategy could advance high-performance short-wavelength optoelectronic devices.

Language: Английский

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Multi‐π‐Stacked Through‐Space Charge‐Transfer Emitters with Accelerated Radiative Decay for High‐Efficiency Organic Light‐Emitting Diodes with Suppressed Efficiency Roll‐Offs

Advanced Functional Materials, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 7, 2025

Abstract Through‐space charge‐transfer (TSCT) thermally‐activated delayed fluorescence (TADF) emitters have been extensively explored for organic light‐emitting diodes (OLEDs), but their low radiative decay rates ( k r,s ) remained a formidable obstacle to enhancement of luminescent efficiency (Ф PL and suppression roll‐off the OLED. Here, multi‐π‐stacked TSCT‐TADF with accelerated are developed 3D [fixed acceptor]/donor/[fixed acceptor] structure formed on two individual fluorene bridges. Single‐crystal structures theoretical calculations reveal cis or trans ‐configurations acceptors around central donor double TSCT channels in emitter. In doped films, show green‐blue TADF high up 1.1 × 10 7 s −1 near‐unity Ф , which notably improved compared single‐π‐stacked analog = 2.1 6 0.89). OLEDs based external quantum efficiencies (EQEs) 26.2% EQEs at 1000 cd m −2 (EQE remain 23.4%, superior over device max /EQE 20%/15.6%). A narrowband blue‐green OLED one emitter as sensitizer shows EQE 37.6%/27.7%. The work demonstrates great potential enhancing high‐efficiency roll‐offs.

Language: Английский

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Phosphonium Iodide Featuring Blue Thermally Activated Delayed Fluorescence for Highly Efficient X‐Ray Scintillator

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(46)

Published: July 5, 2024

Organic scintillators are praised for their abundant element reserves, facile preparation procedures, and rich structures. However, the weak X-ray attenuation ability low exciton utilization efficiency result in unsatisfactory scintillation performance. Herein, a new family of highly efficient organic phosphonium halide salts with thermally activated delayed fluorescence (TADF) designed by innovatively adopting quaternary as electron acceptor, while dimethylamine group anions (I

Language: Английский

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Temperature-Adaptive Organic Scintillators for X-ray Radiography

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 16, 2024

Organic phosphorescence or thermally activated delayed fluorescence (TADF) scintillators, while effective in utilizing triplet excitons, are sensitive to temperature changes, which can impact radioluminescence performance. In this study, we have developed a type of temperature-adaptive organic scintillator with and TADF dual emission. These scintillators automatically switch modes enabling efficient from 77 400 K. The highest photoluminescence quantum yield light 83.2% 78,229 ± 562 photons MeV

Language: Английский

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Simultaneously Improving Radiative Decay and Reverse Intersystem Crossing in Space‐Confined Through‐Space Charge‐Transfer (TSCT) Emitter by Strong Intermolecular TSCT Enabled by a Planar Donor

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 35(1)

Published: Sept. 20, 2024

Abstract Simultaneously improving radiative decay and reverse intersystem crossing (RISC) of through‐space charge‐transfer (TSCT) thermally‐activated delayed fluorescence (TADF) emitters has remained a challenge. Here, space‐confined TSCT‐TADF are developed with planar indolo[3,2,1‐ kl ]phenoxazine donor, spiro‐carbon‐fixed benzophenone acceptor, fluorene (for 1 ) or xanthene 2 bridge. Close, cofacial donor/acceptor alignments efficient intramolecular TSCT have been observed for both emitters. Intriguingly, emitter exhibits an intermolecular interaction as strong the one, which opens TSCT, rate ( k r,s to same level featuring much stronger interaction. The also largely enhances RISC ). In 20 wt.% doped films, show green TADF high / at 1.1 × 10 7 s −1 /1.3 6 1.2 /7.7 5 , respectively. Organic light–emitting diodes (OLEDs) using external quantum efficiencies (EQEs) up 27.5% low‐efficiency roll‐offs. Hyperfluorescent OLEDs sensitizers afford narrowband blue‐green emission EQEs 30.6% suppressed efficiency work reveals that strengthening is promising avenue simultaneously improve r,s, high‐performance OLEDs.

Language: Английский

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Near-infrared organic scintillators for efficient X-ray imaging via singlet and triplet to doublet energy transfer

Science China Materials, Journal Year: 2025, Volume and Issue: unknown

Published: March 10, 2025

Language: Английский

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Through-Space Charge Transfer Polybenzonorbornenes with Thermally Activated Delayed Fluorescence and Full-Color Piezochromism Property

Chemical Communications, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Through-space charge-transfer polybenzonorbornenes, consisting of a carbazole donor and dimesitylboron acceptor in the ortho-positions phenyl units on benzonorbornene repeating unit, have been developed, revealing efficient thermally activated delayed fluorescence emission full-colorpiezochromism.

Language: Английский

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Controlling Noncovalent π–π Interactions in Dimers Toward Thermally Reversible Switching Between Monomer and Excimer Fluorescence

Advanced Functional Materials, Journal Year: 2025, Volume and Issue: unknown

Published: March 18, 2025

Abstract Thermochromic fluorescent materials (TFMs) have garnered great attention due to their unique fluorescence transition responsive temperature. However, the application of TFMs is limited defects such as low thermosensitivity and a high temperature‐responsive threshold value. In this case, work explores feasible strategy for designing TFMs. On one hand, sterically hindered unilateral tetraphenylethylene (TPE) substituent introduced into pyrene chromophore in meta‐ linkage mode. This type molecular architecture aimed at integration both aggregation‐induced emission (AIE) character isolated π–π dimer stacking, facilitating achievement contrast intensity (i.e., strongly emissive aggregation state versus weakly dispersion state) color ( i.e , excimer monomer). other an effective matrix platform featured with alky chain length‐dependent temperature‐induced phase constructed assist fabrication desired patterns through temperature‐controlled reversible between crystalline non‐dispersion liquated states. The findings demonstrate that these studied can be potentially applied temperature indicators switchable dynamic interior decoration, which provides new avenue design

Language: Английский

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Two-coordinate copper(I) complexes enable efficient X-ray scintillation and imaging

Science China Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 20, 2025

Language: Английский

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Scintillators with aggregation-induced emission

Chem, Journal Year: 2025, Volume and Issue: unknown, P. 102534 - 102534

Published: April 1, 2025

Language: Английский

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