Chiral TADF Polymers Realizing Highly‐Efficient Deep‐Red Circularly Polarized Electroluminescence Over 660 nm

Abstract

Circularly polarized electroluminescence (CPEL) from thermally activated delayed fluorescence (TADF) emitters have been widely reported in recent years. However, a universal strategy for designing deep‐red chiral TADF emitters is still unexplored. Herein, to address the problem, a pair of chiral donor intermediates are designed and synthesized for preparing deep‐red chiral TADF emitters, and two novel chiral TADF polymers R‐P and S‐P are developed through this strategy. The polymers exhibit intense mirror‐image circularly polarized luminescence (CPL) signals in toluene dilute solution. Besides, a series of solution‐processed circularly polarized polymer light‐emitting diode (CP‐PLED) devices are fabricated with R‐P and S‐P. The corresponding devices achieve persuasive performance with external quantum efficiencies (EQEs) of 6.2% and 5.8% at the wavelength of 662 nm, respectively. Besides, mirror‐image CPEL signals are detected with electroluminescence dissymmetry factors (gEL) of +1.6 × 10−3 and −1.7 × 10−3 from the corresponding CP‐PLED devices, respectively.

Advances in circularly polarized luminescence materials based on chiral macrocycles

“…Although great progress has been made in CPL materials based on chiral macrocycles, the design and synthesis of macrocycle-based CPEL materials, which would be more valuable in optoelectronic technology, still remain a great challenge. 65–68 Recently, Chen's group reported a pair of binaphthol-based chiral macrocycles (+)-( R , R )- 51 and (−)-( S , S )- 51 with both thermally activated delayed fluorescence (TADF) and high-efficiency CPEL properties (Fig. 36).…”

High Comprehensive Circularly Polarized Electroluminescence Performance Improved by Chiral Coassembled Host Materials

“…[24][25][26] Generally, chiral self-assembly or coassembly processes are facilitated through chiral host-guest combinations or induction through electrostatic interactions, cooperative hydrogen bonds, 𝜋-𝜋 stacking interactions or intermolecular Förster resonance energy transfer (FRET). [27][28][29][30][31][32][33][34][35] In 2013, Fuchter's group reported the creative EMLs using an achiral liquid crystal fluorescent poly[9,9-dioctylfluoreneco-benzothiadiazole] (F8BT) doped with chiral 1-aza [6]helicene enantiomers and the resulting CP-OLEDs emitted green CP-EL with large g EL values. [36] Until now, several successful examples of high-performance CP-OLEDs have been achieved by the intermolecular chirality induction mechanism from chiral inducers to achiral luminescent materials.…”

“…These include chiral organic small molecules, chiral fluorescent polymers, chiral thermally activated delayed fluorescent dyes, chiral Eu(III)/Ir(III)/Pt(II)-containing complexes, and so on. [4][5][6][7][8][9][10][11][12][13] At the same time, some feasible methods have also been…”

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

“…5 Notably, the latter approach offers advantages in terms of meeting commercial demands for large-scale synthesis and economic feasibility compared to the former approach, as CP-TADF features can be derived from readily available enantiopure substrates, thus circumventing challenging chiral resolution processes. 6 However, the drawback associated with the latter strategy is the tendency of CP-TADF emitters to exhibit low luminescence dissymmetry factors ( g PL ). 7 This limitation primarily stems from the limited involvement of frontier molecular orbitals (FMOs) and the electronic transition from the lowest singlet state (S 1 ) to the ground state (S 0 ) for most commercially available chiral sources, such as [1,1′-binaphthalene]-2,2′-diol.…”