Au⋅⋅⋅H−C Interactions Support a Robust Thermally Activated Delayed Fluorescence (TADF) Gold(I) Complex for OLEDs with Little Efficiency Roll‐Off and Good Stability

Wen

et al. 2023

Mater. Chem. Front.

Section: Resultsmentioning

confidence: 99%

Section: Synthesis and Characterizationmentioning

confidence: 99%

High-efficiency and stable red to near-infrared organic light-emitting diodes using dinuclear platinum(ii) complexes

Wen

et al. 2023

Mater. Chem. Front.

“…1.97–1.98 Å for carbene–Au–amide) has been ascribed to the stronger trans ‐effect of the aryl ligand. [ 50 ] DCzBN–Au has a slightly bent coordination geometry (C NHC AuC aryl bond angle: 172.98°), presumably due to the crystallization effect. The carbene motif is twisted with respect to the BN plane with a dihedral angle of ≈20°, revealing its tendency to have a co‐planar orientation akin to previous findings on carbene–Au–L (L = ligand) complexes devoid of steric hindrance between the two ligands.…”

Section: Resultsmentioning

confidence: 99%

Metal‐Perturbed Multiresonance TADF Emitter Enables High‐Efficiency and Ultralow Efficiency Roll‐Off Nonsensitized OLEDs with Pure Green Gamut

Zhong

et al. 2022

Advanced Materials

Self Cite

Multiresonance (MR)‐induced thermally activated delayed fluorescence (TADF) emitters based on B‐ and N‐embedded polycyclic aromatics are desirable for ultrahigh‐definition organic light‐emitting diodes (OLEDs) due to their high photoluminescence quantum yield (PLQY) and narrow bandwidth. But the reverse intersystem crossing (RISC) rates of MR‐TADF emitters are usually small, resulting in severe device efficiency roll‐off at high brightness. To solve this issue, a sensitizer for the MR‐TADF emitter has been required. Herein, a new MR‐TADF emitter is developed through coordination of Au with B/N‐embedded polycyclic ligand. Benefitting from the Au perturbation, the RISC rate is dramatically accelerated to 2.3 × 107 s−1, leading to delayed fluorescence lifetime as short as 4.3 µs. Meanwhile, the PLQY of 95% and full width at half maximum of 39 nm (0.18 eV) are essentially unchanged after metal coordination. Therefore, a high PLQY, short delayed fluorescence lifetime, and high color purity are concurrently realized in a single TADF emitter. Accordingly, vacuum‐deposited OLEDs exhibit high‐performance electroluminescence with a maximum external quantum efficiency (EQE) of 35.8% without sensitization. The EQE is maintained as high as 32.3% at 10 000 cd m−2. Furthermore, solution‐processed OLED based on the emitter also achieves excellent performance with a maximum EQE of 25.7% and a small efficiency roll‐off.

“…Such depressed non-radiative decay was also observed in some recent TADF CMAs with orthogonal geometry. [30,31] For completeness, the even higher k nr in Cu2 and Cu3 than Cu1 and Cu4 can be blamed to additional energy losses via free motions of alkyl substituents.…”

Section: Zuschriftenmentioning

confidence: 99%

A Configurationally Confined Thermally Activated Delayed Fluorescent Two‐Coordinate Cu^I Complex for Efficient Blue Electroluminescence

Liu

et al. 2023

Angewandte Chemie

Thermally activated delayed fluorescence (TADF) from linear two-coordinate coinage metal complexes is sensitive to the geometric arrangement of the ligands. Herein we realize the tuning of configuration from coplanar to orthogonal gradually by variation of substituents. In a complex with confined twist configuration, its blue emission peaking at 458 nm presents a high Φ PL of 0.74 and a short τ TADF of 1.9 μs, which indicates a fast enough k r,TADF of 3.9 × 10 5 s À 1 and a depressed k nr of 1.4 × 10 5 s À 1 . Such outstanding luminescent properties are attributed to the proper overlap of HOMO and LUMO on Cu I d orbitals that guarantees not only small ΔE ST but also sufficient transition oscillator strength for fast k r;S 1 . Vacuum-deposited blue OLEDs with either doped or host-free emissive layer present external quantum efficiencies over 20 % and 10 %, respectively, demonstrating the practicality of the configurationally confined strategy for efficient linear Cu I TADF emitters.