Red/Near‐Infrared Thermally Activated Delayed Fluorescence OLEDs with Near 100 % Internal Quantum Efficiency

Abstract

Developing red thermally activated delayed fluorescence (TADF) emitters,a ttainable for both high-efficient red organic light-emitting diodes (OLEDs) and non-doped deep red/near-infrared (NIR) OLEDs,ischallenging. Now,two red emitters,B PPZ-PXZ and mDPBPZ-PXZ, with twisted donor-acceptor structures were designed and synthesized to study molecular design strategies of high-efficiency red TADF emitters.B PPZ-PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with aphotoluminescence quantum yield (F PL )of100 AE 0.8 %and external quantum efficiency (EQE) of 25.2 %i nadoped OLED.Its non-doped OLED has an EQE of 2.5 %owingto unavoidable intermolecular p-p interactions.mDPBPZ-PXZ releases two pyridine substituents from its fused acceptor moiety.A lthough mDPBPZ-PXZ realizes al ower EQE of 21.7 %i nt he doped OLED,i ts non-doped device shows asuperior EQE of 5.2 %with adeep red/NIR emission at peak of 680 nm.

Manipulating exciton dynamics of thermally activated delayed fluorescence materials for tuning two-photon nanotheranostics

“…1d and g, both neat thin lms of AT and PT show prompt decays in the range of 100 ns and delayed proles in the range of 200 ms at room temperature, which are similar to most TADF emitters. 19,34,35 More importantly, the delayed lifetimes of both thin lms decrease along with the increase of temperature from 100 K to 300 K, revealing that the rate of reverse ISC from T 1 states to S 1 states increases with the rising temperature, 22 which further conrm that AT and PT are TADF molecules.…”

Structural Design of Blue‐to‐Red Thermally‐Activated Delayed Fluorescence Molecules by Adjusting the Strength between Donor and Acceptor

“…They developed a new acceptor moiety (mDPBPZ) containing five rings with two nitrogen atoms, and two pyridine rings. [76] These rotatable pyridines reduce the rigidity of the molecule and inhibit the ππ packing. Two target molecules BPPZ-PXZ and mDPBPZ-PXZ were synthesized with BPPZ and mDPBPZ as acceptor segments and PXZ employed as the D segments (Figure 15).In doped CBP film, the ΔE ST of them are determined to be 0.03 and 0.04 eV, respectively, thereby guaranteeing the effective RISC process of both materials.…”

Integrating Time‐Resolved Imaging Information by Single‐Luminophore Dual Thermally Activated Delayed Fluorescence

“…[2] In contrast, time-resolved (TR) fluorescence imaging can effectively shield the endogenous fluorescence.U pon this approach, fluorescent probes with am uch longer lifetimes than the nanosecond scale are required. [3] Organic molecules possessing thermally activated delayed fluorescence (TADF) [4] are superior prototypes for this purpose,a sthey have long-lived emission and can avoid the usage of toxic metal ions in the phosphors. [5] Thedelay of fluorescence operates in the microor even to millisecond lifetime range in TADF systems, [6] which thus can meet the requirements of TR fluorescence imaging.…”