Emerging circularly polarized thermally activated delayed fluorescence materials and devices

Abstract

Thermally activated delayed fluorescent (TADF) materials are capable of converting non-radiative triplets into radiative singlets in the presence of a tiny singlet-triplet splitting. Circularly polarized luminescent (CPL) materials with TADF properties have shown great potential in unity exciton utilization as well as high circularly polarized dissymmetry factors |gPL|. When employed in organic light-emitting devices (OLEDs), circularly polarized electroluminescence (CPEL) with high dissymmetry factors |gEL| is essential for reducing the optical loss and improving the quality of 3D, augment-reality, and virtual reality displays. This Perspective summarizes the recent advances in the cutting-edge research of CP-TADF-OLEDs and addresses the challenges in molecular and device engineering.

Designs and Applications of Circularly Polarized Thermally Activated Delayed Fluorescence Molecules

“…This progress report aims to describe the molecular designs merging TADF and CPL, discuss device performances, and finally highlight current and future challenges in this burgeoning field. [ 12 ]…”

Thermally Activated Delayed Fluorescence beyond Through‐Bond Charge Transfer for High‐Performance OLEDs

“…Most of the previously reported TADF emitters are dominated by intra-TBCT, in spite of donor-π-acceptor, donor-σ-acceptor, or donor-acceptor-donor architecture. [83][84][85][86][87][88][89][90][91][92] Recently, the TADF emitters featuring intra-TSCT are very attractive due to the merits of small ΔE ST , large transition dipole moment, fast RISC, and thus excellent EL performances. Herein, the emerging molecular designs covering the intra-TSCT induced TADF will be deliberately discussed and compared.…”

An S-Shaped Double Helicene Showing both Multi-Resonance Thermally Activated Delayed Fluorescence and Circularly Polarized Luminescence

“…[36][37][38] Thus, the development of CPL emitters has become the subject of intense examination in recent years. [25,26,30,39,40] The CPL intensity of a chiral molecule can be quantified by the dissymmetry factor, gPL, which is represented by equation ( 1): [41][42][43] g PL =…”

“…[43,[50][51][52] Presently, there exists a small number of organic compoudns displaying CP-TADF, with most of the reports emerging over the past few years. A number of these have been used in CP-TADF OLEDs, [25,40,[53][54][55] showing maximum external quantum efficiencies (EQEmax) surpassing 30% [55] but with gEL typically ≤ 10 -3 (Figure 1a). The overwhelming majority of compounds showing CP-TADF are based on a donor-acceptor design that incorporates a remote stereogenic unit (asymmetric centre or axis) to induce chirality, [25,36,39,53,56,57] and so do not show narrow emission spectra.…”

“…A number of these have been used in CP-TADF OLEDs, [25,40,[53][54][55] showing maximum external quantum efficiencies (EQEmax) surpassing 30% [55] but with gEL typically ≤ 10 -3 (Figure 1a). The overwhelming majority of compounds showing CP-TADF are based on a donor-acceptor design that incorporates a remote stereogenic unit (asymmetric centre or axis) to induce chirality, [25,36,39,53,56,57] and so do not show narrow emission spectra. A material showing concomitantly narrow emission, TADF and CPL would be of significant interest, and a potential class of compound that can meet these requirements are chiral MR-TADF compounds.…”