Harnessing of Cooperative Cu⋅⋅⋅H Interactions for Luminescent Low-Coordinate Copper(I) Complexes towards Stable OLEDs.

Although two-coordinate Cu(I) complexes are highly promising low-cost emitters for organic light-emitting diodes (OLEDs), the exposed metal center in the linear coordination geometry makes them suffer from poor stability. Herein, we describe a strategy to develop stable carbene-Cu-amide complexes through installing intramolecular noncovalent Cu⋅⋅⋅H interactions. The employment of 13H-dibenzo[a,i]carbazole (DBC) as the amide ligand leads to short Cu⋅⋅⋅H distances in addition to the Cu-N coordination bond.

Ag(i) emitters with ultrafast spin-flip dynamics for high-efficiency electroluminescence.

Carbene-metal-amide (CMA) complexes are appealing emitters for organic light-emitting diodes (OLEDs). However, little is known about silver(i)-CMA complexes, particularly electroluminescent ones. Here we report a series of Ag(i)-CMA complexes prepared using benzothiophene-fused carbazole derivatives as amide ligands.

Improving the Blue Color Purity of Tetradentate Pt(II) Complexes with the Assistance of F⋅⋅⋅H Interaction towards High-Performance Blue Phosphorescent OLEDs with EQE over 33 .

Among the various challenges in the field of organic light-emitting diodes (OLEDs), simultaneously achieving high efficiency, a long lifespan, and a narrow full-width at half maximum (FWHM) in blue OLEDs remains a significant hurdle. Herein, we demonstrate a strategy to improve the color purity of tetradentate Pt(II) complexes with the assistance of ⋅⋅⋅H interaction by incorporating trifluoromethyl (-CF) groups into the well-known blue tetradentate Pt(II) phosphorescent complex. The results show that the different substitution positions of -CF have significantly varying effects on the FWHM values of the complexes; specifically, introducing -CF on the benzene ring of carbazole effectively reduces the FWHM, while introducing it on the benzene ring linked to the carbene unit has a minimal impact.

High-Performance Narrowband Pure-Green OLEDs with Gamut Approaching BT.2020 Standard: Deuteration Promotes Device Efficiency and Lifetime Simultaneously.

In order to fulfill the demand for ultrahigh definition organic light-emitting diodes (OLEDs), pure-green emitters with Commission Internationale de l'Éclairage (CIE) y-coordinate over 0.71 are in urgent demand. Meanwhile, the high device efficiency, small efficiency roll-off, and operational lifetime also remain challenging issues.

Synergistic π-Extension and Peripheral-Locking of B/N-Based Multi-Resonance Framework Enables High-Performance Pure-Green Organic Light-Emitting Diodes.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters offer natural advantages for creating power-efficient, wide-color-gamut OLEDs. However, current green MR-TADF emitters face challenges in simultaneously achieving high color purity and efficient reverse inter-system crossing (RISC), leading to suboptimal device performance. In this study, we propose a synergistic molecular design approach that combines π-extension and peripheral locking to address these challenges.

Harmonization of rapid triplet up-conversion and singlet radiation enables efficient and stable white OLEDs.

White organic light-emitting diodes (WOLEDs) hold significant promise in illumination and displays, but achieving high efficiency while maintaining stability is an ongoing challenge. Here, we strategically combine a blue donor-acceptor thermally activated delayed fluorescence (TADF) emitter featuring rapid reverse intersystem crossing rate and a yellow multi-resonance TADF emitter renowned for the fast radiative transition process to achieve warm WOLEDs with exceptional power efficiency exceeding 190 lm W and external quantum efficiency (EQE) of 39%, setting records for WOLEDs. Meanwhile, these devices also exhibit an extended operational lifetime (LT) of 446 h at an initial luminance of 1000 cd m.

Gold Coordination-Accelerated Multi-Resonance TADF Emission for Efficient Solution-Processible Ultrapure Deep-Blue OLEDs.

Multi-resonance (MR) type emitters have emerged as highly promising candidates for high-resolution organic light-emitting diodes (OLEDs). However, thermally activated delayed fluorescence (TADF) emissions with simultaneous short excited state lifetimes and ultrapure blue color (a CIE close to 0.046 and an emission peak >440 nm) have rarely been obtained for MR emitters.

Multi-resonance thermally activated delayed fluorescence polymers for high-efficiency and narrowband solution-processed green OLEDs.

A series of green multi-resonance thermally activated delayed fluorescence polymeric emitters featuring conjugation-interrupted main chains were facilely prepared metal-free superacid-catalyzed Friedel-Crafts polyhydroxyalkylation. These emitters exhibited photoluminescence quantum yields of up to 76% and small full-widths at half maximum of 35-38 nm in toluene. The corresponding solution-processed OLEDs achieved an excellent maximum external quantum efficiency of 19.

Achieving 19.5% Efficiency via Modulating Electronic Properties of Peripheral Aryl-Substituted Small-Molecule Acceptors.

The advancement of acceptors plays a pivotal role in determining photovoltaic performance. While previous efforts have focused on optimizing acceptor-donor-acceptor-donor-acceptor (A-DA-D-A)-typed acceptors by adjusting side chains, end groups, and conjugated extension of the electron-deficient central A unit, the systematic exploration of the impact of peripheral aryl substitutions, particularly with different electron groups, on the A unit and its influence on device performance is still lacking. In this study, three novel acceptors - QxTh, QxPh, and QxPy - with distinct substitutions on the quinoxaline (Qx) are designed and synthesized.

Approaching 20% Efficiency in Ortho-Xylene Processed Organic Solar Cells by a Benzo[a]phenazine-Core-Based 3D Network Acceptor with Large Electronic Coupling and Long Exciton Diffusion Length.

High-performance organic solar cells often rely on halogen-containing solvents, which restrict the photovoltaic industry. Therefore, it is imperative to develop efficient organic photovoltaic materials compatible with halogen-free solvents. Herein, a series of benzo[a]phenazine (BP)-core-based small-molecule acceptors (SMAs) achieved through an isomerization chlorination strategy is presented, comprising unchlorinated NA1, 10-chlorine substituted NA2, 8-chlorine substituted NA3, and 7-chlorine substituted NA4.

Enhanced Emitting Dipole Orientation Based on Asymmetric Iridium(III) Complexes for Efficient Saturated-Blue Phosphorescent OLEDs.

Three novel asymmetric Ir(III) complexes have been rationally designed to optimize their emitting dipole orientations (EDO) and enhance light outcoupling in blue phosphorescent organic light-emitting diodes (OLEDs), thereby boosting their external quantum efficiency (EQE). Bulky electron-donating groups (EDGs), namely: carbazole (Cz), di-tert-butyl carbazole (tBuCz), and phenoxazine (Pxz) are incorporated into the tridentate dicarbene pincer chelate to induce high degree of packing anisotropy, simultaneously enhancing their photophysical properties. Angle-dependent photoluminescence (ADPL) measurements indicate increased horizontal transition dipole ratios of 0.

Nonplanar structure accelerates reverse intersystem crossing of TADF emitters: nearly 40% EQE and relieved efficiency roll off.

Exploring strategies to enhance reverse intersystem crossing (RISC) is of great significance to develop efficient thermally activated delayed fluorescent (TADF) molecules. In this study, we investigate the substantial impact of nonplanar structure on improving the rate of RISC ( ). Three emitters based on spiroacridine donors are developed to evaluate this hypothesis.

Enhanced Thermally Activated Delayed Fluorescence by Sole Coordination: From an Organic Molecule to Its Zinc Complex.

A BPAPTPyC organic molecule containing a sandwich structural chromophore is designed and synthesized to produce blue thermally activated delayed fluorescence (TADF). The chromophore is composed of two di(4--butylphenyl)amino donors and one inserted terpyridyl acceptor hitched at positions 1, 8, and 9 of a single carbazole via the -phenylene group, in which the multiple space π-π interactions between the donor and acceptor enable the molecule to possess the TADF feature with a high energy emission at 470 nm but a low photoluminescence quantum yield (PLQY) and a small proportion of the delayed component. In contrast, the corresponding Zn(BPAPTPyC)Cl complex has a high PLQY and a short lifetime with a red-shifted emission due to the enhanced rigidity and electron accepting ability of the terpyridyl group from coordination.

Three-Charge (0, -1, -2) Ligand-Based Binuclear and Mononuclear Deep-Red Phosphorescent Iridium Complexes Bearing Benzo[]oxazole-2-Thiol Ligand.

A new class of three-charge (0, -1, -2) ligand-based binuclear and mononuclear iridium complexes bearing benzo[]oxazole-2-thiol ligand have been synthesized. Notably, the binuclear complexes ( and ) can be generated at low temperatures by reacting the iridium complex precursors ( and ) with equal amounts of the benzo[]oxazole-2-thiol ligands, while the corresponding mononuclear complexes ( and ) are formed at high temperatures. X-ray diffraction analysis shows that the benzo[]oxazole-2-thiol ligand plays an unusual and interesting bridging role in binuclear complexes and induces rich intermolecular and intramolecular interactions, while in mononuclear complexes, it forms an interesting four-membered ring coordination.

A diphenylphosphine oxide decorated multi-resonance TADF emitter for narrowband green electroluminescence with an EQE of 32.4.

A new narrowband thermally activated delayed fluorescence emitter, PhCzBN-PO, was developed by incorporating the diphenylphosphine oxide (DPPO) group into a multi-resonance core. The unique properties of DPPO enabled PhCzBN-PO to achieve pure green emission and a nonplanar structure. The resulting electroluminescent devices achieved high external quantum efficiencies up to 32.

A Difluoro-Methoxylated Ending-Group Asymmetric Small Molecule Acceptor Lead Efficient Binary Organic Photovoltaic Blend.

Developing a new end group for synthesizing asymmetric small molecule acceptors (SMAs) is crucial for achieving high-performance organic photovoltaics (OPVs). Herein, an asymmetric small molecule acceptor, BTP-BO-4FO, featuring a new difluoro-methoxylated end-group is reported. Compared to its symmetric counterpart L8-BO, BTP-BO-4FO exhibits an upshifted energy level, larger dipole moment, and more sequential crystallinity.

Synthetic progress of organic thermally activated delayed fluorescence emitters C-H activation and functionalization.

Thermally activated delayed fluorescence (TADF) emitters have become increasingly prominent due to their promising applications across various fields, prompting a continuous demand for developing reliable synthetic methods to access them. This review aims to highlight the progress made in the last decade in synthesizing organic TADF compounds through C-H bond activation and functionalization. The review begins with a brief introduction to the basic features and design principles of TADF emitters.

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

Multi-boron-embedded multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters show promise for achieving both high color-purity emission and high exciton utilization efficiency. However, their development is often impeded by a limited synthetic scope and excessive molecular weights, which challenge material acquisition and organic light-emitting diode (OLED) fabrication by vacuum deposition. Herein, we put forward a B‒N covalent bond-involved π-extension strategy via post-functionalization of MR frameworks, leading to the generation of high-order B/N-based motifs.

Dynamic Reversible Full-Color Piezochromic Fluorogens Featuring Through-Space Charge-Transfer Thermally Activated Delayed Fluorescence and their Application as X-Ray Imaging Scintillators.

Thermally activated delayed fluorescence (TADF) emitters featuring through-space charge transfer (TSCT) can be excellent candidates for piezochromic luminescent (PCL) materials due to their structural dynamics. Spatial donor-acceptor (D-A) stacking arrangements enable the modulation of inter- and intramolecular D-A interactions, as well as spatial charge transfer states, under varying pressure conditions. Herein, we demonstrate an effective approach toward dynamic reversible full-color PCL materials with TSCT-TADF characteristics.

Orienting Group Directed Cascade Borylation for Efficient One-Shot Synthesis of 1,4-BN-Doped Polycyclic Aromatic Hydrocarbons as Narrowband Organic Emitters.

1,4-BN-doped polycyclic aromatic hydrocarbons (PAHs) have emerged as very promising emitters in organic light-emitting diodes (OLEDs) due to their narrowband emission spectra that may find application in high-definition displays. While considerable research has focused on investigating the properties of these materials, less attention has been placed on their synthetic methodology. Here we developed an efficient synthetic method for 1,4-BN-doped PAHs, which enables sustainable production of narrowband organic emitting materials.

Integration of fine-tuned chiral donor with hybrid long/short-range charge-transfer for high-performance circularly polarized electroluminescence.

The synergistic integration of a fine-tuned chiral donor with a hybrid long/short-range charge-transfer mechanism offers an accessible pathway to construct highly efficient circularly polarized emitters. Consequently, a notable dissymmetry factor of 1.6 × 10, concomitantly with a record-setting maximum external quantum efficiency of 37.