Deep‐Blue Narrowband Hetero[6]helicenes Showing Circularly Polarized Thermally Activated Delayed Fluorescence Toward High‐Performance OLEDs

Advanced Materials, Journal Year: 2023, Volume and Issue: 36(1)

Published: Nov. 14, 2023

Abstract Helicenes exhibit substantial potential as circularly polarized luminescence (CPL) active molecules. However, their application in organic light‐emitting diodes (CP‐OLEDs) is typically hindered by the challenge of integrating both high color purity and efficient triplet‐harvesting capability, particularly blue spectral region. Herein, a series hetero[6]helicene‐based emitters that strategically engineered through helical extension deep‐blue double‐boron‐based multiple resonance thermally activated delayed fluorescence (MR‐TADF) motif, introduced. Importantly, does not cause apparent structural deformation or perturb frontier molecular orbitals; thus, preserving emission MR‐TADF characteristics parent molecule. This approach also leads to reduced reorganization energy, resulting with narrower linewidth higher photoluminescence quantum yield. Further, motif enhances racemization barrier improved CPL performance dissymmetry factor values up 1.5 × 10 −3 . Exploiting these merits, devices incorporating chiral dopants demonstrate within Broadcast Service Television 2020 color‐gamut range, record external efficiencies (EQEs) 29.3%, have distinctive electroluminescence (CPEL) signals. Overall, authors’ findings underscore promising strategy for designing narrowband chiroptical materials advancing high‐definition displays.

Language: Английский

---

B,N‐Embedded Hetero[9]helicene Toward Highly Efficient Circularly Polarized Electroluminescence

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(18)

Published: Feb. 21, 2024

The intrinsic helical π-conjugated skeleton makes helicenes highly promising for circularly polarized electroluminescence (CPEL). Generally, carbon undergo low external quantum efficiency (EQE), while the incorporation of a multi-resonance thermally activated delayed fluorescence (MR-TADF) BN structure has led to an improvement. However, reported B,N-embedded all show dissymmetry factors (g

Language: Английский

---

Deep-blue organic light-emitting diodes for ultrahigh-definition displays

Nature Photonics, Journal Year: 2024, Volume and Issue: 18(11), P. 1161 - 1169

Published: Aug. 19, 2024

Language: Английский

---

Acceleration of reverse intersystem crossing in multi-resonance TADF emitter

Chem, Journal Year: 2024, Volume and Issue: 10(5), P. 1485 - 1501

Published: Feb. 15, 2024

Language: Английский

---

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

National Science Review, Journal Year: 2024, Volume and Issue: 11(6)

Published: March 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.

Language: Английский

---

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

Advanced Materials, Journal Year: 2024, Volume and Issue: 36(30)

Published: May 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.

Language: Английский

---

Nitrogen Effects Endowed by Doping Electron-Withdrawing Nitrogen Atoms into Polycyclic Aromatic Hydrocarbon Fluorescence Emitters

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(23), P. 15977 - 15985

Published: May 7, 2024

Unveiling innovative mechanisms to design new highly efficient fluorescent materials and, thereby, fabricate high-performance organic light-emitting diodes (OLEDs) is a concerted endeavor in both academic and industrial circles. Polycyclic aromatic hydrocarbons (PAHs) have been widely used as emitters blue OLEDs, but device performances are far from satisfactory. In response, we propose the concept of "nitrogen effects" endowed by doping electron-withdrawing nitrogen atoms into PAH fluorescence emitters. The presence n orbital on imine conducive promoting electron coupling, which leads increased molar absorptivity an accelerated radiative decay rate emitters, thereby facilitating Förster energy transfer (FET) process OLEDs. Additionally, electronically withdrawing enhances host–guest interactions, positively affecting FET horizontal orientation factor emitting layer. To validate concept, cobalt-catalyzed multiple C–H annulation has utilized incorporate alkynes imine-based frameworks, enables various imine-embedded (IE-PAH) cyclization demonstrates notable regioselectivity, offering practical tool precisely introduce peripheral groups at desired positions with bulky alkyl units positioned adjacent atoms, were previously beyond reach through Friedel–Crafts reaction. Blue OLEDs fabricated IE-PAHs exhibit outstanding performance maximum external quantum efficiency (EQEmax) 32.7%. This achievement sets groundbreaking record for conventional PAH-based EQEmax 24.0%.

Language: Английский

---

Purely organic room-temperature phosphorescence sensitizers for highly efficient hyperfluorescence OLEDs

Science Advances, Journal Year: 2025, Volume and Issue: 11(12)

Published: March 21, 2025

Multiresonance thermally activated delayed fluorescence (MR-TADF) emitters are promising candidates for organic light-emitting diodes (OLEDs) with high color quality. However, in most cases, noble metal–containing phosphors required as sensitizers MR-TADF to improve their electroluminescence (EL) performances, which may lead cost and environmental pollution. Herein, an efficient purely room-temperature phosphorescence (RTP) material, 3,2-PIC-TXT, fast radiation is developed. It not only exhibits impressive EL performances emitter outstanding external quantum efficiency (EQE) of 33.2%, higher than that Ir(ppy) 3 (25.2%), but also functions remarkably a sensitizer green (BN2, tCzphB-Ph, tCzphB-Fl). The hyperfluorescence OLEDs using 3,2-PIC-TXT provide ultrahigh EQEs 40.9 43.8%, superior those based on (37.0 38.0%), along superb purity excellent operational stability. These the best devices RTP materials reported so far.

Language: Английский

---

Carbazole‐Decorated Organoboron Emitters with Low‐Lying HOMO Levels for Solution‐Processed Narrowband Blue Hyperfluorescence OLED Devices

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(47)

Published: Sept. 30, 2023

The hyperfluorescence has drawn great attention in achieving efficient narrowband emitting devices based on multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters. However, solution-processed pure blue is still a challenge, due to the unbalanced charge transport and serious exciton quenching caused by that holes are easily trapped high-lying HOMO (the highest occupied molecular orbital) level of traditional diphenylamine-decorated Here, we developed two organoboron emitters with low-lying levels decorating MR-TADF core weakly electron-donating carbazoles, which could suppress hole trapping effect reducing traps between host emitter from deep (0.40 eV) shallow (0.14/0.20 ones for facilitating formation, as well avoiding quenching. And large dihedral angle carbazole makes act steric hindrance inhibit aggregation. Accordingly, optimized simultaneously realize record external quantum efficiency 29.2 %, emission full-width at half-maximum 16.6 nm, color CIE coordinates (0.139, 0.189), best result organic light-emitting diodes

Language: Английский

---

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

Advanced Optical Materials, Journal Year: 2023, Volume and Issue: 11(22)

Published: Oct. 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

Language: Английский

---