Peripheral Substitution Engineering of MR‐TADF Emitters Embedded With B‒N Covalent Bond Towards Efficient BT.2020 Blue Electroluminescence

Advanced Materials, Год журнала: 2024, Номер unknown

Опубликована: Окт. 15, 2024

Compared with the classical boron/nitrogen (B/N) doped ones, multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters embedded B-N covalent bond behave a significantly blue-shifted narrowband TADF, and thus show greater potential in ultrapure blue organic light-emitting diodes (OLEDs). As proof of concept, herein peripheral substitution engineering is demonstrated based on such B‒N parent core. The simple approach found to ensure easy synthesis via one-pot lithium-free borylation-annulation, manipulate excited states through different electronic coupling between core substituent, introduce steric hindrance minimize unwanted spectral broadening. Impressively, OLEDs are realized give high external quantum efficiency 20.3% together Commission Internationale de l'Éclairage coordinates (0.152, 0.046). performance well competent those B/N MR-TADF emitters, clearly highlighting that framework novel promising paradigm towards efficient BT.2020 standard.

Язык: Английский

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Achieving Narrowband and Stable Pure Blue Organic Light‐Emitting Diodes by Employing Molecular Vibration Limited Strategies in the Extended π‐Conjugated Indolocarbazole Skeleton

Advanced Science, Год журнала: 2025, Номер unknown

Опубликована: Янв. 13, 2025

Abstract B‐ and N‐heterocyclic fluorophores have reveal promising efficiency in blue organic light‐emitting diodes (OLEDs) with small full‐width‐at‐half‐maximum (FWHM). However, their structural determinants for spectral broadening operating stability are still needed to be investigated further. Herein, a novel multi‐N‐heterocycles Diindolo[3,2,1jk:3′,2′,1′jk]dicarbazole[1,2‐b:4,5‐b] (DIDCz) is proposed manipulate the emission color toward pure region by extending π‐conjugation of N‐π‐N bridge. By utilizing computed technique, interrelationships between indolocarbazole (ICz)‐cyclization sites defined. Molecular backbone modifications involving optimized 2,3,6,7‐ICz cyclization steric hindrance substituents conducive restricting swing peripheral bonds stretching resonances polycyclic aromatic hydrocarbon (PAH) frameworks, thereby contributing reduction shoulder peaks. Consequently, DIDCz‐based chromophore exhibited narrowband FWHM only 15 nm, achieving highly efficient (external quantum efficiencies 8.87% triplet–triplet fusion fluorescence 22.3% sensitized fluorescence) long‐term (95% initial luminance 1000 cd m −2 , T95 = 1545 h) electroluminescence performances, showing one most stable OLEDs among reported PAH chromophores. The current achievements offer new perspective manage precisely based on molecular vibration limiting technique.

Язык: Английский

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Blue Multiple‐Resonance Thermally Activated Delayed Fluorescence Materials

Advanced Optical Materials, Год журнала: 2025, Номер unknown

Опубликована: Фев. 8, 2025

Abstract Organic light‐emitting diodes (OLEDs) exhibit significant advantages in the fields of ultra‐high‐definition (UHD) displays and wearable devices. However, developing low‐cost, high‐efficiency, high‐purity blue emission materials remains a challenge for academia industry. While thermally activated delayed fluorescence (TADF) meet low‐cost manufacturing needs achieve 100% internal quantum efficiency, their charge‐transfer excited states lead to broad spectra that don't BT.2020 standard. Fortunately, multiple resonance (MR) strategy offers an effective solution creating TADF with high color purity. Through careful structural design precise tuning state energy levels, MR‐TADF can easily full‐width at half‐maximum (FWHM) less than 30 nm. Nevertheless, it still faces challenges, such as severe aggregation‐induced quenching efficiency roll‐off. Herein, this work overviews recent progress devices, introduce representative molecular strategies aimed suppressing concentration quenching, enhancing reverse intersystem crossing rates, achieving deep emission, which will aid future endeavors develop more efficient, stable devices suitable UHD display applications.

Язык: Английский

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π‐Extended Phenoxazine‐Based Asymmetric MR‐TADF Emitters for Narrow Emission Band Green OLEDs with a Power Efficiency of 150 lmW^−m, an EQE of 27%, and an LT₉₅ of Over 3000 h at 1000 cdm⁻²

Advanced Optical Materials, Год журнала: 2024, Номер unknown

Опубликована: Окт. 9, 2024

Abstract Although multi‐resonance thermally activated delayed fluorescent (MR‐TADF) emitters simultaneously achieve high color purity and efficiency in organic light‐emitting devices (OLEDs), MR‐TADF‐based OLEDs suffer from severe roll‐off lifetime issues for practical application. To overcome these issues, a key solution is hyper OLED technology sensitized by TADF or phosphorescent emitters. In this study, series of π‐extended phenoxazine‐based asymmetric MR‐TADF long lifetime, low‐power consumption, narrow emission band green developed. As sensitizer, well‐known emitter used, fac ‐tris(2‐phenylpyridinato‐C2,N)iridium(III) [Ir(ppy) 3 ]. Consequently, with power 150 lm W −1 , an external quantum 27%, LT 95 over 3000 h at brightness 1000 cdm −2 . These performances are among the best scientific literature.

Язык: Английский

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In Situ Substrate Temperature Control for High-Performance Blue-Emitting OLEDs with Extended Operational Lifetime

ACS Applied Materials & Interfaces, Год журнала: 2025, Номер unknown

Опубликована: Фев. 27, 2025

Organic light-emitting diodes (OLEDs) are currently a leading technology in display applications, providing superior optoelectrical performance and image quality compared to other sources. A challenge OLEDs is prolonging the operational lifetime of blue pixels achieve nearly 100% internal quantum efficiency, comparable red green pixels. Recently, there has been growing interest controlling molecular orientation emitting layer (EML) enhance address this issue. low driving current at specific luminance allows significantly their under constant efficiency. In study, investigation focused on whether substrate temperature (Tsub) predominantly influences host molecules EML. Tsub enhances hole mobility EML, enabling recombination inside As result, it was observed that blue-emitting using technique increase by approximately 6.6 times when -4 °C 40 Tsub, eliminating material deformation weak organic layer.

Язык: Английский

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White Organic Light-emitting Devices Based on Phosphor-sensitized Fluorescence

Acta Physica Sinica, Год журнала: 2024, Номер 74(2), С. 0 - 0

Опубликована: Дек. 10, 2024

Although phosphorescent organic light-emitting diodes can have 100% internal quantum efficiency (IQE), the IQE usually roll-off at high current densities due to triplet-triplet annihilation. Phosphor-sensitized fluorescence realize energy transfer between and fluorescent emitters, used suppress efficiency roll-off tune color of device. Based on this consideration, white emission including different colors emitters be expected. Herein, White devices (WOLED) are fabricated by combining ultra-thin layer insertion doping, in which laser dyes DCM (4-(Dicyanomethylene)-2-methyl-6-(4-dimethyl-aminostyryl)-4H-pyran), iridium complexes Ir(ppy)₃ (tris(2-phenylpyridine)iridium), biphenyl ethylene derivatives BCzVB (1,4-bis[2- (3-N-ethylcarbazoryl)vinyl]benzene) were as red, green blue respectively. By tuning doping concentration emitter CBP (4,4’-N,N’-dicarbazole-biphyenyl) host with layers both sides CBP:Ir(ppy)₃ system, red inserting layer, three balanced, emissions obtained device, highest external is 2.5% (current 5.1 cd/A), maximum brightness 12400 cd/m², Commission Internationale de l'Eclairage (CIE) co-ordinates reach ideal light equilibrium point (0.33, 0.33) a density 1 mA/cm². The acquisition attributed suitable ratio position DCM, effectively balance ratios green, primary colors. results indicate that partially transferring triplet singlet excitons phosphor-sensitized scheme, electroluminescent efficiency, thereby reducing consumption providing more space for promoting OLED applications.

Язык: Английский

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Fast‐Response and High‐Color‐Purity RGB Fluorescent Organic Light‐Emitting Diodes for Visible Light Communication System

Advanced Optical Materials, Год журнала: 2024, Номер unknown

Опубликована: Дек. 26, 2024

Abstract The integration of red, green, and blue (RGB) organic light‐emitting diodes (OLEDs) is pursued to achieve a significant advancement in high‐speed visible light communication (VLC). With their rapid decay rates less than few nanoseconds, fluorescent emitters enable fast data transmission by facilitating prompt emission. Here, implementing top‐emitting architecture with strong cavity, the spectral crosstalk among RGB colors addressed narrowing spectra enhancing bandwidth OLEDs. Furthermore, co‐emitter configuration improves optoelectrical characteristics OLEDs improving horizontal transition dipole ratios photoluminescence quantum yield. exhibiting nanosecond‐level times, proposed OLED platform achieves an order magnitude increase −3 dB cut‐off frequency exceeding 1 MHz across all channels compared phosphorescent thermally activated delayed These findings underscore potential technology advance systems, paving way for enhanced capabilities.

Язык: Английский

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