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

Chemical Society Reviews, Год журнала: 2024, Номер 53(3), С. 1624 - 1692

Опубликована: Янв. 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.

Язык: Английский

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B‒N covalent bond-involved π-extension of multiple resonance emitters enables high-performance narrowband electroluminescence

National Science Review, Год журнала: 2024, Номер 11(6)

Опубликована: Март 23, 2024

ABSTRACT Multi-boron-embedded multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters show promise for achieving both high color-purity emission and exciton utilization efficiency. However, their development is often impeded by a limited synthetic scope excessive molecular weights, which challenge material acquisition organic light-emitting diode (OLED) fabrication vacuum deposition. Herein, we put forward B‒N covalent bond-involved π-extension strategy via post-functionalization of MR frameworks, leading to the generation high-order B/N-based motifs. The structurally electronically extended π-system not only enhances rigidity narrow linewidth but also promotes reverse intersystem crossing mitigate efficiency roll-off. As illustrated examples, ultra-narrowband sky-blue (full-width at half-maximum as small 8 nm in n-hexane) have been developed with multi-dimensional improvement photophysical properties compared precursor emitters, enables narrowband OLEDs external quantum efficiencies (EQEmax) up 42.6%, company alleviated decline brightness, representing best reported single-host OLEDs. success these highlights effectiveness our design advanced MR-TADF confirms extensive potential high-performance optoelectronic devices.

Язык: Английский

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Nitrogen‐Embedding Strategy for Short‐Range Charge Transfer Excited States and Efficient Narrowband Deep‐Blue Organic Light Emitting Diodes

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(35)

Опубликована: Июнь 3, 2024

The development of deep-blue organic light-emitting diodes (OLEDs) featuring high efficiency and narrowband emission is great importance for ultrahigh-definition displays with wide color gamut. Herein, based on the nitrogen-embedding strategy modifying short range charge transfer excited state energies multi-resonance (MR) thermally activated delayed fluorescence (TADF) emitters, we introduce one or two nitrogen atoms into central benzene ring a versatile boron-embedded 1,3-bis(carbazol-9-yl)benzene skeleton. This approach resulted in stabilization highest occupied molecular orbital energy levels formation intramolecular hydrogen bonds, thus systematic hypsochromic shifts narrowing spectra. In toluene solution, heterocyclic-based MR-TADF molecules, Py-BN Pm-BN, exhibit emissions photoluminescence quantum yields 93 % 94 %, narrow full width at half maximum 14 13 nm, respectively. A hyperfluorescent OLED exhibited external 27.7 desired purity Commission Internationale de L'Eclairage (CIE) coordinates (0.150, 0.052). These results demonstrate significant potential deep blue emitters.

Язык: Английский

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Efficient Deep‐Blue Multiple‐Resonance Emitters Based on Azepine‐Decorated ν‐DABNA for CIE_y below 0.06

Advanced Materials, Год журнала: 2024, Номер 36(30)

Опубликована: Май 2, 2024

Abstract Ultrapure deep‐blue emitters are in high demand for organic light‐emitting diodes (OLEDs). Although color coordinates serve as straightforward parameters assessing purity, precise control over the maximum wavelength and full‐width at half‐maximum is necessary to optimize OLED performance, including luminance efficiency luminous efficacy. Multiple‐resonance (MR) promising candidates achieving ideal luminescence properties; consequently, a wide variety of MR frameworks have been developed. However, most these experience displacement from color, which limits their practical applicability. Therefore, molecular design that compatible with modulating energy levels output particularly valuable. Here, it demonstrated azepine donor unit induces an appropriate blue‐shift emission while maintaining efficient characteristics, photoluminescence quantum yield, narrow emission, fast reverse intersystem crossing rate. OLEDs using newly developed based on ν ‐DABNA framework simultaneously exhibit ≈30%, efficacy ≈20 lm W −1 , exceptional purity Commission Internationale de l’Éclairage low (0.14, 0.06), notably operational stability. These results demonstrate unprecedentedly compared those observed previously reported emitters.

Язык: Английский

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Introducing Spiro‐locks into the Nitrogen/Carbonyl System towards Efficient Narrowband Deep‐blue Multi‐resonance TADF Emitters

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(40)

Опубликована: Авг. 19, 2023

The current availability of multi-resonance thermally activated delayed fluorescence (MR-TADF) materials with excellent color purity and high device efficiency in the deep-blue region is appealing. To address this issue emerged nitrogen/carbonyl MR-TADF system, we propose a spiro-lock strategy. By incorporating spiro functionalization into concise molecular skeleton, series emitters (SFQ, SOQ, SSQ, SSeQ) can enhance rigidity, blue-shift emission peak, narrow band, increase photoluminescence quantum yield by over 92 %, suppress intermolecular interactions film state. referent CZQ without structure has more planar its bluer solution state redshifts 40 nm serious spectrum broadening low PLQY As result, SSQ achieves an external 25.5 % peak at 456 small full width half maximum 31 simple unsensitized device, significantly outperforming CZQ. This work discloses importance spiro-junction modulating emitters.

Язык: Английский

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Combining Carbazole Building Blocks and ν‐DABNA Heteroatom Alignment for a Double Boron‐Embedded MR‐TADF Emitter with Improved Performance

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(32)

Опубликована: Июнь 13, 2023

Building blocks and heteroatom alignments are two determining factors in designing multiple resonance (MR)-type thermally activated delayed fluorescence (TADF) emitters. Carbazole-fused MR emitters, represented by CzBN derivatives, the of ν-DABNA star series MR-TADF emitters that show impressive performances from aspects building alignments, respectively. Herein, a novel analog, Π-CzBN, featuring alignment is developed via facile one-shot lithium-free borylation. Π-CzBN exhibits superior photophysical properties with photoluminescence quantum yield close to 100 % narrowband sky blue emission full width at half maximum (FWHM) 16 nm/85 meV. It also gives efficient TADF small singlet-triplet energy offset 40 meV fast reverse intersystem crossing rate 2.9×105 s-1 . The optimized OLED using as emitter achieves an exceptional external efficiency 39.3 low roll-off 20 1000 cd m-2 495 nm FWHM 21 nm/106 meV, making it one best reported devices based on comprehensive performance.

Язык: Английский

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Marching Toward Long‐Wavelength Narrowband Emissive Multi‐Resonance Delayed Fluorescence Emitters for Organic Light Emitting Diodes

Advanced Optical Materials, Год журнала: 2023, Номер 11(22)

Опубликована: Окт. 4, 2023

Abstract Over the past decade, thermally activated delayed fluorescence (TADF) emitters have garnered tremendous impetus because of their ability to harvest 100% excitons for light emission in organic emitting diodes (OLEDs). However, despite superior external quantum efficiencies (> 35%), broad spectra with associated full‐width‐at‐half maximum (FWHM > 70 nm) present a limiting factor that must be solved. Recently, multiple‐resonance TADF (MR‐TADF) materials based on heteroatom doped polyaromatic hydrocarbons gained astonishing attention owing remarkable narrowband < 30 nm). majority reported MR‐TADF falls blue/green region, which inevitably jeopardizes application full‐color OLEDs. Therefore, there is an urgent need develop new molecular designs expanding color‐gamut emitters, i.e., λ em 550 nm without compromising emission. To best current knowledge, no detailed reviews focusing different design strategies producing long‐wavelength been date. this end, review highlighting recent advances constructing presented, and photophysics OLED performance discussed. Finally, status future prospects are

Язык: Английский

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Tailored Design of π‐Extended Multi‐Resonance Organoboron using Indolo[3,2‐b]Indole as a Multi‐Nitrogen Bridge

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(48)

Опубликована: Окт. 9, 2023

Extending the π-skeletons of multi-resonance (MR) organoboron emitters can feasibly modulate their optoelectronic properties. Here, we first adopt indolo[3,2-b]indole (32bID) segment as a multi-nitrogen bridge and develop high-efficiency π-extended narrowband green emitter. This moiety establishes not only high-yield one-shot multiple Bora-Friedel-Crafts reaction towards MR skeleton, but compact N-ethylene-N motif for red-shifted emission. An emission peak at 524 nm, small full width half maximum 25 nm high photoluminescence quantum yield 96 % are concurrently obtained in dilute toluene. The extended molecular plane also results large horizontal emitting dipole orientation ratio 87 %. A external efficiency (EQE) 36.6 power 135.2 lm/W thereafter recorded corresponding device, allowing low roll-off with EQEs 34.5 28.1 luminance 1,000 cd/m2 10,000 , respectively.

Язык: Английский

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Shining Light on Inverted Singlet–Triplet Emitters

Journal of Chemical Theory and Computation, Год журнала: 2023, Номер 20(2), С. 902 - 913

Опубликована: Ноя. 22, 2023

The inversion of the lowest singlet and triplet excited states, observed in several triangle-shaped organic molecules containing conjugated carbon nitrogen atoms, is an astonishing result that implies breakdown Hund's rule. phenomenon attracted interest for its potential toward harvesting LEDs. On a more fundamental vein, singlet–triplet (ST) sheds new light on role electron correlations excited-state landscape π-conjugated molecules. Relying celebrated Pariser–Parr–Pople model, simplest model correlated electrons systems, we demonstrate ST does not require nor any specific molecular symmetry. Indeed, strictly non-overlapping HOMO LUMO orbitals but rather small gap exchange integral between frontier orbitals.

Язык: Английский

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Rational Medium‐Range Charge Transfer Strategy Toward Highly Efficient Violet‐Blue Organic Light‐Emitting Diodes with Narrowed Emission

Advanced Materials, Год журнала: 2023, Номер 36(2)

Опубликована: Ноя. 16, 2023

Abstract The spectral narrowing engineering of pure‐organic emitters attracts great research interests in realizing high color purity. Here, the adjusted medium‐range charge transfer (MCT) strategy TIC‐BO with rigid planar structure by fusing two typical UV‐emitting multiple resonance (MR) fragments via ingenious double‐halide cyclized coupling reaction is reported. resulting MCT nature shows efficient violet‐blue emission dilute toluene and evaporated host–guest films, desirably narrowed spectra are achieved suppression structural relaxation shortened states. single‐doped device as emitter electroluminescence peaked at 428 nm full‐width half‐maximum 43 (0.28 eV), Commission Internationale de l’Éclairage coordinates (0.160, 0.050). A maximum external quantum efficiency (EQE max ) 20.50% achieved, which among best results corresponding emitting region. Further introduction a stronger electron‐donating carbazole group makes TIC‐BNO exhibit red‐shifted sky‐blue MR‐dominant properties, good performance received EQE 34.58%. outstanding performances successfully demonstrate significance prospect proposed molecular design strategy.

Язык: Английский

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