Quenching‐Resistant Multiresonance TADF Emitter Realizes 40% External Quantum Efficiency in Narrowband Electroluminescence at High Doping Level

Advanced Materials, Journal Year: 2021, Volume and Issue: 34(3)

Published: Nov. 12, 2021

Multiresonance thermally activated delayed fluorescence (MR-TADF) emitters manifest great potential for organic light-emitting diodes (OLEDs) due to their high exciton-utilization efficiency and narrowband emission. Nonetheless, tendency toward self-quenching caused by strong interchromophore interactions would induce doping sensitivity deteriorate the device performances, effective strategy construct quenching-resistant without sacrifycing color purity is still be developed. By segregating planar MR-TADF skeleton using two bulky carbazolyl units, herein a highly emissive molecule with enhanced quenching resistance reported. The steric effect largely removes formation of detrimental excimers/aggregates, boosts performance corresponding devices maximum external quantum (EQEmax ) up 40.0% full width at half (FWHM) 25 nm, representative only example single OLED that can concurrently achieve narrow bandwidth EL surpassing 40% date. Even ratio 30 wt%, EQEmax retained 33.3% nearly unchanged emission spectrum. This work provides viable approach realize doping-insensitive extreme high-end displays.

Language: Английский

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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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Achieving Ultimate Narrowband and Ultrapure Blue Organic Light‐Emitting Diodes Based on Polycyclo‐Heteraborin Multi‐Resonance Delayed‐Fluorescence Emitters

Advanced Materials, Journal Year: 2021, Volume and Issue: 34(9)

Published: Dec. 8, 2021

To achieve an ultimate wide color gamut for ultrahigh-definition displays, there is great demand the development of organic light-emitting diodes (OLEDs) enabling monochromatic, ultrapure blue electroluminescence (EL). Herein, high-efficiency and OLEDs based on polycyclo-heteraborin multi-resonance thermally activated delayed fluorescence (MR-TADF) materials, BOBO-Z, BOBS-Z, BSBS-Z, are reported. The key to design present luminophores exquisite combination interplay multiple boron, nitrogen, oxygen, sulfur heteroatoms embedded in a fused polycyclic π-system. Comprehensive photophysical computational investigations this family MR-TADF materials reveal that systematic implementation chalcogen (oxygen sulfur) atoms can finely modulate emission while maintaining narrow bandwidth, as well spin-flipping rates between excited singlet triplet states. Consequently, BSBS-Z demonstrate narrowband EL emission, with peaks at 445-463 nm full width half maxima 18-23 nm, leading Commission Internationale de l'Éclairage-y coordinates range 0.04-0.08. Particularly, incorporating sulfur-doped BOBS-Z notably high maximum external quantum efficiencies 26.9% 26.8%, respectively, small efficiency roll-offs achieved concurrently.

Language: Английский

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Approaching Nearly 40% External Quantum Efficiency in Organic Light Emitting Diodes Utilizing a Green Thermally Activated Delayed Fluorescence Emitter with an Extended Linear Donor–Acceptor–Donor Structure

Advanced Materials, Journal Year: 2021, Volume and Issue: 33(44)

Published: Sept. 13, 2021

Abstract Thermally activated delayed fluorescence (TADF) emitters featuring preferential horizontal emitting dipole orientation (EDO) are in urgent demand for enhanced optical outcoupling efficiency organic light‐emitting diodes (OLEDs). However, simultaneously manipulating EDO and optoelectronic properties remains a formidable challenge. Here, an extended linear D–A–D structure with both enlarged donor (D) acceptor (A) π‐systems is established, not only elaborately parallel molecular along its long axis by multi‐driving‐forces high ratio ( Θ // ), but also delocalizing distribution of frontier energy levels optimized electronic properties. The proof‐of‐the‐concept emitter affords 92%, photoluminescence quantum yield 95%, fast reverse intersystem crossing rate 1.16 × 10 6 s ‐1 . corresponding OLED achieves champion maximum external 39.1% among all green TADF devices without any light‐extraction techniques, together power 112.0 lm W alleviated roll‐off. These findings may inspire even better full‐color that push the device toward theoretical limits.

Language: Английский

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Wide‐Range Color Tuning of Narrowband Emission in Multi‐resonance Organoboron Delayed Fluorescence Materials through Rational Imine/Amine Functionalization

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(43), P. 23142 - 23147

Published: Aug. 18, 2021

Abstract Establishing a simple and versatile design strategy to finely modulate emission colors while retaining high luminescence efficiency color purity remains an appealing yet challenging task for the development of multi‐resonance‐induced thermally activated delayed fluorescence (MR‐TADF) materials. Herein, we demonstrate that strategic introduction electron‐withdrawing imine electron‐donating amine moieties into boron‐embedded 1,3‐bis(carbazol‐9‐yl)benzene skeleton enables systematic hypsochromic bathochromic shifts narrowband emissions, respectively. By this method, effective electroluminescence tuning was accomplished over wide visible range from deep‐blue yellow (461–571 nm), using same MR molecular system, without compromising very narrow spectral features. Deep‐blue organic light‐emitting diodes with maximum external quantum efficiencies as 19.0–29.2 % superb could be produced family color‐tunable MR‐TADF emitters.

Language: Английский

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Fabrication of Circularly Polarized MR‐TADF Emitters with Asymmetrical Peripheral‐Lock Enhancing Helical B/N‐Doped Nanographenes

Advanced Materials, Journal Year: 2021, Volume and Issue: 34(1)

Published: Oct. 24, 2021

Circularly polarized thermally activated delayed fluorescence (CP-TADF) and multiple-resonance (MR-TADF), which exhibit novel circularly luminescence excellent color fidelity, respectively, have gained immense popularity. In this study, integrated CP-TADF MR-TADF (CPMR-TADF) are prepared by strategic design synthesis of asymmetrical peripherally locked enantiomers, separated denoted as (P,P″,P″)-/(M,M″,M″)-BN4 (P,P″,P″)-/(M,M″,M″)-BN5 TADF light (CPL) properties. As the entire molecular frame participates in frontier orbitals, resulting helical chirality (+)/(-)-BN4- (+)/(-)-BN5-based solution-processed organic light-emitting diodes (OLEDs) helps achieving a narrow full width at half maximum (FWHM) 49/49 48/48 nm high external quantum efficiency (EQE) 20.6%/19.0% 22.0%/26.5%, respectively. Importantly, unambiguous electroluminescence signals with dissymmetry factors (gEL ) +3.7 × 10-3 /-3.1 (BN4) +1.9 /-1.6 (BN5) obtained. The results indicate successful exploitation CPMR-TADF-emitter-based OLEDs to three characteristics: efficiency, purity, light.

Language: Английский

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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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Thermally Activated Delayed Fluorescence Material: An Emerging Class of Metal‐Free Luminophores for Biomedical Applications

Advanced Science, Journal Year: 2021, Volume and Issue: 8(24)

Published: Oct. 27, 2021

Abstract The development of simple, efficient, and biocompatible organic luminescent molecules is great significance to the clinical transformation biomaterials. In recent years, purely thermally activated delayed fluorescence (TADF) materials with an extremely small single‐triplet energy gap (Δ E ST ) have been considered as most promising new‐generation electroluminescence emitters, which enormous breakthrough in optoelectronics. By merits unique photophysical properties, high structure flexibility, reduced health risks, such metal‐free TADF luminophores attracted tremendous attention biomedical fields, including conventional imaging, time‐resolved imaging sensing, photodynamic therapy. However, there currently no systematic summary for applications, presented this review. Besides a brief introduction major developments material, typical mechanisms fundamental principles on design strategies nanomaterials are subsequently described. Importantly, specific emphasis placed discussion various applications. Finally, authors make forecast remaining challenges future developments. This review provides insightful perspectives clear prospects towards rapid biomedicine, will be highly valuable exploit new materials.

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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