Synergetic Modulation of Steric Hindrance and Excited State for Anti‐Quenching and Fast Spin‐Flip Multi‐Resonance Thermally Activated Delayed Fluorophore

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(16)

Published: Feb. 8, 2024

Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials hold great promise for advanced high-resolution organic light-emitting diode (OLED) displays. However, persistent challenges, such as severe aggregation-caused quenching (ACQ) and slow spin-flip, hinder their optimal performance. We propose a synergetic steric-hindrance excited-state modulation strategy MR-TADF emitters, which is demonstrated by two blue IDAD-BNCz TIDAD-BNCz, bearing sterically demanding 8,8-diphenyl-8H-indolo[3,2,1-de]acridine (IDAD) 3,6-di-tert-butyl-8,8-diphenyl-8H-indolo[3,2,1-de]acridine (TIDAD), respectively. These rigid bulky IDAD/TIDAD moieties, with appropriate electron-donating capabilities, not only effectively mitigate ACQ, ensuring efficient luminescence across broad range of dopant concentrations, but also induce high-lying charge-transfer excited states that facilitate triplet-to-singlet spin-flip without causing undesired emission redshift or spectral broadening. Consequently, implementation high doping level resulted in highly narrowband electroluminescence, featuring remarkable full-width at half-maximum 34 nm record-setting external quantum efficiencies 34.3 % 31.8 maximum 100 cd m

Language: Английский

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Highly efficient pure-blue organic light-emitting diodes based on rationally designed heterocyclic phenophosphazinine-containing emitters

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: July 22, 2024

Abstract Multi-resonance thermally activated delayed fluorophores have been actively studied for high-resolution photonic applications due to their exceptional color purity. However, these compounds encounter challenges associated with the inefficient spin-flip process, compromising device performance. Herein, we report two pure-blue emitters based on an organoboron multi-resonance core, incorporating a conformationally flexible donor, 10-phenyl-5 H -phenophosphazinine 10-oxide (or sulfide). This design concept selectively modifies orbital type of high-lying excited states charge transfer configuration while simultaneously providing necessary conformational freedom enhance density without sacrificing We show that different embedded phosphorus motifs (phosphine oxide/sulfide) donor can finely tune electronic structure and freedom, resulting in accelerated process through intense spin-vibronic coupling, achieving over 20-fold increase reverse intersystem crossing rate compared parent emitter. Utilizing emitters, achieve high-performance organic light-emitting diodes, showcasing top-tier external quantum efficiency 37.6% reduced roll-offs. proposed strategy not only conventional notion electron-donors are undesirable constructing narrowband but also offer pathway designing efficient narrow-spectrum blue diodes.

Language: Английский

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Dynamic Reversible Full‐Color Piezochromic Fluorogens Featuring Through‐Space Charge‐Transfer Thermally Activated Delayed Fluorescence and their Application as X‐Ray Imaging Scintillators

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(20)

Published: Feb. 28, 2024

Abstract Thermally activated delayed fluorescence (TADF) emitters featuring through‐space charge transfer (TSCT) can be excellent candidates for piezochromic luminescent (PCL) materials due to their structural dynamics. Spatial donor‐acceptor (D−A) stacking arrangements enable the modulation of inter‐ and intramolecular D−A interactions, as well spatial states, under varying pressure conditions. Herein, we demonstrate an effective approach toward dynamic reversible full‐color PCL with TSCT‐TADF characteristics. Their single crystals exhibit a full‐color‐gamut process spanning range 170 nm. Moreover, TSCT‐TADF‐PCL display unity photoluminescence quantum yield, show promising application in X‐ray scintillator imaging.

Language: Английский

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

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: May 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.

Language: Английский

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Narrowband clusteroluminescence with 100% quantum yield enabled by through-space conjugation of asymmetric conformation

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: July 30, 2024

Different from traditional organic luminescent materials based on covalent delocalization, clusteroluminescence nonconjugated luminogens relies noncovalent through-space conjugation of electrons. However, such spatial electron delocalization is usually weak, resulting in low efficiency and board emission peak due to multiple vibrational energy levels. Herein, several are constructed by employing biphenyl as the building unit reveal structure-property relationship solve current challenges. The intramolecular can be gradually strengthened introducing units stabilized rigid molecular skeleton intermolecular interactions. Surprisingly, narrowband with full width at half-maximum 40 nm 100% successfully achieved via an asymmetric conformation, exhibiting comparable performance conjugated luminogens. This work realizes highly efficient highlights essential role structural conformation manipulating photophysical properties unconventional materials.

Language: Английский

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Ternary Wrapped Nitrogen/Carbonyl Multiresonance TADF Emitters with Quenching-Resistant Abilities

ACS Materials Letters, Journal Year: 2024, Volume and Issue: 6(4), P. 1380 - 1387

Published: March 11, 2024

Multiresonance thermally activated delayed fluorescence (MR-TADF) materials with rigid planar structures offer high photoluminescence quantum yields and narrowband emission for display applications. However, aggregation-caused quenching (ACQ) caused by chromophore interactions can detrimentally affect device performance. To address this, we modified MR-TADF chromophores bulky terphenyl groups, successfully synthesizing the blue emitter TTPQAO. Its distorted structure effectively suppresses ACQ. Remarkably, at doping concentrations from 2 to 20 wt %, external efficiency only decreased 4.3% a slight fwhm broadening of 1 nm. Our work provides practical approach mitigate ACQ in TADF materials.

Language: Английский

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Structurally Tunable Donor−Bridge−Fluorophore Architecture Enables Highly Efficient and Concentration‐Independent Narrowband Electroluminescence

Advanced Materials, Journal Year: 2024, Volume and Issue: 36(31)

Published: May 23, 2024

Luminescent materials with narrowband emission have extraordinary significance for developing ultrahigh-definition display. B-N-containing multiple resonance thermally activated delayed fluorescence (MR-TADF) are strong contenders. However, their device performances pervasively encounter detrimental aggregation-caused quenching effect that is highly vulnerable to doping concentration, complicating fabrication. Therefore, constructing efficient and concentration-independent MR-TADF emitters of pragmatic importance improving controllability reproducibility, simplifying manufacturing procedures, conserving production costs. Here, by systematic arrangement donor triphenylamine fluorophore BNCz on distinct bridges, a spatial confinement strategy has been developed donor-bridge-fluorophore architecture. Structurally fine modulation progressive evolution construct molecular entities congested steric hindrance can suppress intermolecular interactions without substantially affecting the luminescence tone BNCz, resulting in emitters; through isomer engineering, two isomers BN-PCz-TPA TPA-PCz-BN different crystal stacking patterns synthesized altering connection mode between BNCz. As result, BN-PCz-TPA-based showcases maximum external quantum efficiency (EQE) 36.3% narrow full-width at half-maximum 27 nm 10 wt% concentration. Even 20 EQE remains 32.5% spectrum almost unchanged.

Language: Английский

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Tetradentate Pt[O^N^C^N] complexes with peripheral diarylamino substituents for high-performance and stable green organic light-emitting diodes with LT₉₅ of 17 140 h at 1000 cd m⁻²

Journal of Materials Chemistry C, Journal Year: 2024, Volume and Issue: 12(17), P. 6035 - 6045

Published: Jan. 1, 2024

Pt-based green OLEDs exhibit a maximum EQE of up to 29.6% and an LT 95 17 140 hours at 1000 cd m −2 .

Language: Английский

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Deuterated Multiple‐Resonance Thermally Activated Delayed Fluorescence Emitter and Their Application in Vacuum‐Deposited Organic Light‐Emitting Diodes

Advanced Optical Materials, Journal Year: 2024, Volume and Issue: 12(30)

Published: July 17, 2024

Abstract Multiple‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters have garnered significant attention in recent years due to their remarkable properties, such as high luminescent quantum yield, robustness, and compliance with the Broadcast Television 2020 standard for new generation of ultrahigh‐definition. Despite these advancements, operational lifetimes organic light‐emitting diodes (OLEDs) relying on MR‐TADF still fall short practical application. It is believed that enhancement intrinsic molecular stability t Bu‐DABNA , a fundamental backbone emitters, holds great promise be universal strategy all improving OLEDs. Herein, design synthesis targeted deuteration are reported donor and/or where structure‐property relationship between upon isotopic effect device examined. The analogs show gradual increase achieve long‐lifetime LT 80 (80% initial luminance 1000 cd m −2 ) 24.3 h TADF‐sensitized OLED, representing sevenfold when compared undeuterated counterpart. This strategic approach underlines importance structural modification materials toward stability.

Language: Английский

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A Multiresonant Thermally Activated Delayed Fluorescent Dendrimer with Intramolecular Energy Transfer: Application for Efficient Host‐Free Green Solution‐Processed Organic Light‐emitting Diodes

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

Published: Jan. 9, 2025

Abstract The development of narrowband emissive, bright, and stable solution‐processed organic light‐emitting diodes (SP‐OLEDs) remains a challenge. Here, strategy is presented that merges within single emitter TADF sensitizer responsible for exciton harvesting an MR‐TADF motif provides bright emission. This design also shows strong resistance to aggregate formation aggregation‐cause quenching. It based on known DtBuCzB with donor‐acceptor moiety consisting either tert ‐butylcarbazole donors ( tBuCzCO 2 HDCzB ) or second‐generation carbazole‐based donor dendrons 2GtBuCzCO benzoate acceptor. acts as antenna transfers these excitons via Förster resonance energy transfer the emissive core. SP‐OLEDs thus show very high maximum external quantum efficiencies (EQE max 27.9 22.0%) minimal efficiency roll‐off out 5000 cd m −2 .

Language: Английский

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