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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Charge Transfer Excited State Promoted Multiple Resonance Delayed Fluorescence Emitter for High-Performance Narrowband Electroluminescence

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(23), P. 12550 - 12560

Published: June 5, 2023

Multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters are promising candidates for narrowband organic light-emitting diodes, but their electroluminescent performance is typically hindered by the slow reverse intersystem crossing rate (kRISC). Herein, we present an effective strategy to introduce a multichannel (RISC) pathway with large spin-orbit coupling orthogonally linking electron-donating unit MR framework. Through delicate manipulation of excited-state energy levels, additional intersegmental charge transfer triplet state could be "silently" induced without perturbing character lowest excited singlet state. The proof-of-concept emitter CzBN3 not only affords 23-fold increase kRISC compared its prototypical skeleton also realizes close-to-unity photoluminescence quantum yield, radiative constant, and very narrow emission spectrum. These merits enable high maximum external efficiency (EQEmax) up 37.1% alleviated roll-off in sensitizer-free device (EQE1000 = 30.4%), further boost (EQEmax/1000 42.3/34.1%) realized hyperfluorescent device. state-of-the-art validates superiority our molecular design strategy.

Language: Английский

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Organoboron-based multiple-resonance emitters: synthesis, structure–property correlations, and prospects

Chemical Society Reviews, Journal Year: 2024, Volume and Issue: 53(3), P. 1624 - 1692

Published: Jan. 1, 2024

This review highlights organoboron-based multiple-resonance compounds’ synthetic strategies classified as one-pot borylation, one-shot and late-stage functionalisation, explores material structure–photophysical property correlations.

Language: Английский

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Solution‐Processable Pure‐Red Multiple Resonance‐induced Thermally Activated Delayed Fluorescence Emitter for Organic Light‐Emitting Diode with External Quantum Efficiency over 20 %

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 62(7)

Published: Dec. 13, 2022

Abstract Developing solution‐processable red organic light‐emitting diodes (OLEDs) with high color purity and efficiency based on multiple resonance thermally activated delayed fluorescence (MR‐TADF) is a formidable challenge. Herein, by introducing auxiliary electron donor acceptor moieties into the highest occupied molecular orbital (HOMO) lowest unoccupied (LUMO) distributed positions of skeleton simultaneously, an effective strategy to obtain MR‐TADF emitters was represented. The proof‐of‐the‐concept molecule BN‐R exhibits narrowband pure‐red emission at 624 nm, luminous 94 % narrow bandwidth 46 nm. Notably, fabricated OLED state‐of‐the‐art external quantum over 20 Commission Internationale de I’Éclairage coordinates (0.663, 0.337) long operational lifetime (LT 50 ) 1088 hours initial luminance 1000 cd m −2 .

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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Triphenylamine‐Functionalized Multiple‐Resonance TADF Emitters with Accelerated Reverse Intersystem Crossing and Aggregation‐Induced Emission Enhancement for Narrowband OLEDs

Advanced Functional Materials, Journal Year: 2023, Volume and Issue: 33(12)

Published: Jan. 8, 2023

Abstract Multiple‐resonance (MR) thermal activated delayed fluorescence (TADF) emitters have attracted increasing attention in organic electroluminescence devices, owing to their superior quantum efficiency and narrowband emission for high color purity. However, MR‐TADF materials often suffer from severe aggregation‐caused quenching (ACQ) roll‐off problems due rigid planar structures the lack of sufficient charge‐transfer (CT) characters with inefficient reverse intersystem crossing (RISC). Herein, by attaching electron‐rich triphenylamine (TPA) twisted spatial conformation MR framework, two efficient emitters, namely BNCz‐pTPA BNCz‐mTPA , are developed. The TPA substituent endows new aggregation‐induced enhancement (AIEE) ACQ suppression. unprecedented AIEE‐MR‐TADF exhibit CT character high‐lying triplet excited states faster RISC, while locally‐excited (LE) first singlet state is retained efficiency. An light‐emitting diode (OLED) based on exhibits a maximum external 27.3% slow roll‐off, demonstrating much higher performances than those BNCz ‐based OLED. This study may provide simple but effective approach constructing high‐performance wide‐color‐gamut OLED displays.

Language: Английский

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High‐Efficiency Narrowband Multi‐Resonance Emitter Fusing Indolocarbazole Donors for BT. 2020 Red Electroluminescence and Ultralong Operation Lifetime

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(30)

Published: April 19, 2023

Polycyclic heteroaromatics with multi-resonance (MR) characteristics are attractive materials for narrowband emitters in wide-color-gamut organic light-emitting diodes. However, MR pure-red colors still rare and usually exhibit problematic spectral broadening when redshifting emission. Here, a emitter is reported by fusing indolocarbazole segments into boron/oxygen-embedded skeleton, realizing BT.2020 red electroluminescence the first time together high efficiency an ultralong lifetime. The rigid segment possesses strong electron-donating ability due to its para-positioned nitrogen-π-nitrogen backbone also enlarges π-extension of skeleton suppress structural displacement during radiation, achieving concurrently redshifted narrowed emission spectrum. An maximum at 637 nm full width half-maxima merely 32 (0.097 eV) recorded toluene. corresponding device simultaneously exhibits CIE coordinates (0.708, 0.292) precisely matching point, external quantum 34.4% low roll-off LT95 (time 95% initial luminance) >10 000 h 1000 cd m-2 . These performance superior even those state-of-the-art perovskite quantum-dot-based devices this specific color, paving way toward practical applications.

Language: Английский

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Double boron-embedded multiresonant thermally activated delayed fluorescent materials for organic light-emitting diodes

Communications Chemistry, Journal Year: 2022, Volume and Issue: 5(1)

Published: Nov. 10, 2022

The subclass of multi resonant thermally activated delayed fluorescent emitters (MR-TADF) containing boron atoms has garnered significant attention in the field organic light emitting diode (OLED) research. Among boron-based MR-TADF emitters, double boron-embedded (DB-MR-TADF) show excellent electroluminescence performances with high photoluminescence quantum yields, narrow band emission, and beneficially small singlet-triplet energy levels all full-color gamut regions. This article reviews recent progress DB-MR-TADF particular to molecular design concepts, synthetic routes, optoelectronic properties, OLED performance, giving future prospects for real-world applications.

Language: Английский

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Manipulating Exciton Dynamics toward Simultaneous High-Efficiency Narrowband Electroluminescence and Photon Upconversion by a Selenium-Incorporated Multiresonance Delayed Fluorescence Emitter

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(50), P. 22976 - 22984

Published: Dec. 7, 2022

Multiresonance thermal activated delayed fluorescence (MR-TADF) materials with an efficient spin-flip transition between singlet and triplet excited states remain demanding. Herein, we report MR-TADF compound (BN-Se) simultaneously possessing (reverse) intersystem crossing (ISC/RISC), fast radiative decay, close-to-unity quantum yield, narrowband emission by embedding a single selenium atom into common 4,4'-diazaborin framework. Benefitting from the high RISC efficiency accelerated heavy-atom effect, organic light-emitting diodes (OLEDs) based on BN-Se manifest excellent performance external of up to 32.6% ultralow roll-off 1.3% at 1000 cd m-2. Furthermore, ISC small inherent energy loss also render superior photosensitizer realize first example visible (λex > 450 nm)-to-UV (λem < 350 nm) triplet-triplet annihilation upconversion, (21.4%) extremely low threshold intensity (1.3 mW cm-2). This work not only aids in designing advanced pure molecules exciton dynamics but highlights value compounds beyond OLED applications.

Language: Английский

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Boron‐Based Narrowband Multiresonance Delayed Fluorescent Emitters for Organic Light‐Emitting Diodes

Advanced Photonics Research, Journal Year: 2022, Volume and Issue: 3(11)

Published: Sept. 4, 2022

Recently, the exploration of boron (B)/heteroatom‐embedded polycyclic nanographites featuring multiresonance thermally activated delayed fluorescence (MR‐TADF) garners astonishing attention to promote advancement organic light‐emitting diodes (OLEDs). Contrary traditional donor–acceptor (D–A)‐type TADF emitters, MR‐TADF emitters manifest narrowband emission with full width at half maximum (FWHM ≤ 40 nm) and superior photoluminescence quantum yield (PLQY) coupled small singlet–triplet energy splitting, which appeal their potential as promising candidates in fabricating efficient OLEDs. Growingly, deliver benchmark device performance comparable conventional TADF/phosphorescent emitters. However, they are suffering from major drawbacks such difficult realize full‐color slow exciton upconversion dynamics, aggregation‐caused quenching, severe efficiency roll‐off, poor operational lifetime, jeopardizes practical applicability. Herein, a comprehensive review on B‐based reported till date is presented, focusing different design strategies documented for circumventing aforementioned shortcomings. This divided into several subgroups based color materials draw electronics community toward constructing MR‐OLEDs. Finally, challenges opportunities discussed.

Language: Английский

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