Fused‐Nonacyclic Multi‐Resonance Delayed Fluorescence Emitter Based on Ladder‐Thiaborin Exhibiting Narrowband Sky‐Blue Emission with Accelerated Reverse Intersystem Crossing

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(37), P. 20280 - 20285

Published: July 16, 2021

Abstract Developing organic luminophores with unique capability of strong narrowband emission is both crucial and challenging for the further advancement light‐emitting diodes (OLEDs). Herein, a nanographitic fused‐nonacyclic π‐system ( BSBS‐N1 ), which was strategically embedded multiple boron, nitrogen, sulfur atoms, developed as new multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitter. Narrowband sky‐blue peak at 478 nm, full width half maximum 24 photoluminescence quantum yield 89 % obtained . Additionally, spin‐orbit coupling enhanced by incorporating two thereby facilitating spin‐flipping process between excited triplet singlet states. OLEDs based on MR‐TADF emitter achieved high external electroluminescence efficiency 21.0 %, improved roll‐off.

Language: Английский

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Extending the π‐Skeleton of Multi‐Resonance TADF Materials towards High‐Efficiency Narrowband Deep‐Blue Emission

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(29)

Published: May 10, 2022

Multi-resonance TADF (MR-TADF) emitters are promising for high-resolution OLEDs, but the concurrent optimization of excited-state dynamics and color purity remains a tough challenge. Herein, three deep-blue MR-TADF compounds (BN1-BN3) featuring gradually enlarged ring-fused structures increased rigidity accessed by lithium-free borylation in high yields from same precursor, with all possessing CIEy coordinates below 0.08. Structure-property investigations demonstrate strategic improvement oscillator strength (fosc ) acceleration reverse intersystem crossing (RISC) process extending π-skeleton, where BN3 realizes maximum external quantum efficiency (EQE) 37.6 % reduced roll-off, thus showing best reported OLEDs. The internal regulation these validate general effectiveness to achieve advanced narrowband higher-order boron/nitrogen-based MR motifs.

Language: Английский

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Heavy-atom effect promotes multi-resonance thermally activated delayed fluorescence

Chemical Engineering Journal, Journal Year: 2021, Volume and Issue: 426, P. 131169 - 131169

Published: July 13, 2021

Language: Английский

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Ultrafast Triplet–Singlet Exciton Interconversion in Narrowband Blue Organoboron Emitters Doped with Heavy Chalcogens

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(31)

Published: May 27, 2022

Narrowband emissive organoboron emitters featuring the multi-resonance (MR) effect have now become a critical material component for constructing high-performance organic light-emitting diodes (OLEDs) with pure emission colors. These MR are capable of exhibiting high-efficiency narrowband thermally activated delayed fluorescence (TADF) by allowing triplet-to-singlet reverse intersystem crossing (RISC). However, RISC involving spin-flip exciton upconversion is generally rate-limiting step in overall TADF; hence, deeper understanding and precise control dynamics ongoing crucial challenges. Here, we introduce first emitter (CzBSe) doped selenium atom, demonstrating record-high rate exceeding 108 s-1 , which even higher than its radiation rate. Furthermore, process CzBSe can be accelerated factors ≈20000 ≈800, compared to those oxygen- sulfur-doped homologs (CzBO CzBS), respectively. Unlike CzBO CzBS, photophysical no longer RISC, but process; this behavior completely different from conventional time-delaying TADF limited slow RISC. Benefitting ultrafast spin conversion ability, OLEDs incorporating achieved maximum external electroluminescence quantum efficiency as high 23.9 %, accompanied MR-induced blue significantly alleviated roll-off features.

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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Ambipolar Self‐Host Functionalization Accelerates Blue Multi‐Resonance Thermally Activated Delayed Fluorescence with Internal Quantum Efficiency of 100%

Advanced Materials, Journal Year: 2022, Volume and Issue: 34(17)

Published: March 2, 2022

Emerging multi-resonance (MR) thermally activated delayed fluorescence (TADF) emitters can combine 100% exciton harvesting and high color purity for their organic light-emitting diodes (OLED). However, the highly planar configurations of MR molecules lead to intermolecular-interaction-induced quenching. A feasible way is integrating host segments into molecules, namely a "self-host" strategy, but without involving additional charge transfer and/or vibrational components excited states. Herein, an ambipolar self-host featured emitter, tCBNDADPO, demonstrated, whose segment (DADPO) significantly comprehensively improves TADF properties, especially greatly accelerated singlet radiative rate constant 2.11 × 108 s-1 exponentially reduced nonradiative constants. Consequently, at same time as preserving narrowband blue emission with FWHM ≈28 nm doping concentration 30%, tCBNDADPO reveals state-of-the-art photoluminescence electroluminescence quantum efficiencies 99% respectively. The corresponding internal efficiency supported by ultrasimple trilayer heavily doped device demonstrates feasibility strategy constructing practically applicable materials.

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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Indolo[3,2,1‐jk]carbazole Embedded Multiple‐Resonance Fluorophors for Narrowband Deep‐blue Electroluminescence with EQE≈34.7 % and CIE_y≈0.085

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(22), P. 12269 - 12273

Published: March 20, 2021

Abstract Multiple‐resonance (MR) organic emitters bearing small full‐width at half‐maximum (FWHMs) are of general interest in light‐emitting diodes. Indolo[3,2,1‐ jk ]carbazole (ICz) embedded MR‐fluorophors have demonstrated extremely FWHMs, yet the violet region with low electroluminescence efficiency. Herein, a strategic implementation ICz subunits into MR fluorophors is proposed by taking advantage synergetic effect para ‐positioned nitrogen atoms to enhance electronic coupling decrease emitting energy gap. Deep blue peaking 441 and 447 nm FWHMs only 18 21 thereof obtained, respectively, accompanied ≈90 % photo‐luminance quantum yields. With assistance thermally activated delayed fluorescence sensitizer recycle excitons, corresponding narrowband electroluminescent devices show unprecedent high maximum external efficiencies 32.0 34.7 CIE y 0.10 0.085, respectively.

Language: Английский

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Improved Efficiency and Lifetime of Deep‐Blue Hyperfluorescent Organic Light‐Emitting Diode using Pt(II) Complex as Phosphorescent Sensitizer

Advanced Science, Journal Year: 2021, Volume and Issue: 8(16)

Published: June 16, 2021

Although the organic light-emitting diode (OLED) has been successfully commercialized, development of deep-blue OLEDs with high efficiency and long lifetime remains a challenge. Here, novel hyperfluorescent OLED that incorporates Pt(II) complex (PtON7-dtb) as phosphorescent sensitizer hydrocarbon-based multiple resonance-based fluorophore an emitter (TBPDP ν-DABNA) in device emissive layer (EML), is proposed. Such EML system can promote efficient energy transfer from triplet excited states to singlet fluorophore, thus significantly improving device. As result, using (ν-DABNA) Commission Internationale de L'Eclairage chromaticity coordinate y below 0.1 demonstrated, which attains narrow full width at half maximum ≈17 nm, fourfold increased current 48.9 cd A-1 , 19-fold improved half-lifetime 253.8 h 1000 m-2 compared conventional OLED. The findings lead better understanding performance.

Language: Английский

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Achieving 37.1% Green Electroluminescent Efficiency and 0.09 eV Full Width at Half Maximum Based on a Ternary Boron‐Oxygen‐Nitrogen Embedded Polycyclic Aromatic System

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(23)

Published: March 18, 2022

Abstract Herein, a ternary boron‐oxygen‐nitrogen embedded polycyclic aromatic hydrocarbon with multiple resonance thermally activated delayed fluorescence (MR‐TADF), namely DBNO, is developed by adopting the para boron‐π‐boron and oxygen‐π‐oxygen strategy. The designed molecule presents vivid green emission high photoluminescence quantum yield (96 %) an extremely narrow full width at half maximum (FWHM) of 19 nm/0.09 eV, which surpasses all previously reported TADF emitters to date. In addition, long molecular structure along transition dipole moment direction endows it horizontal emitting ratio 96 %. organic light‐emitting diode (OLED) based on DBNO reveals narrowband peak 504 nm FWHM 24 nm/0.12 eV. Particularly, significantly improved device performance achieved TADF‐sensitization (hyperfluorescence) mechanism, presenting 27 external efficiency (EQE) 37.1

Language: Английский

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