Chiral Conjugated Thermally Activated Delayed Fluorescent Polymers for Highly Efficient Circularly Polarized Polymer Light-Emitting Diodes

Two novel chiral conjugated polymers R-P and S-P designed and synthesized from a pair of circularly polarized thermally activated delayed fluorescence (CP-TADF) enantiomers are presented in this work. The two polymers exhibited excellent TADF properties with small singlet-triplet energy gaps (Delta E-ST) of 0.045 and 0.061 eV and relatively high photoluminescence quantum yields (PLQYs) of 72 and 76%, respectively. Besides, intense mirror-image circularly polarized luminescence signals were detected from R-P and S-P in both solution and film states with dissymmetry factors (vertical bar g(lum)vertical bar) of up to 1.9 x 10(-3). Furthermore, solution-processed circularly polarized polymer light-emitting diodes (CP-PLEDs) fabricated with R-P and S-P achieved high maximum external quantum efficiencies of 14.9 and 15.8% and high maximum brightness (L-max) of 8940 and 12,180 cd/m(2) with yellowish-green emission peaks at 546 and 544 nm, respectively. Moreover, intense circularly polarized electroluminescence signals with electroluminescence dissymmetry factors (g(EL)) of -1.5 x 10(-3) and +1.6 x 10(-3) were detected from the CP-PLED devices fabricated with R-P and S-P, respectively.

Automated summary

Two novel chiral conjugated polymers R-P and S-P with excellent TADF properties and high photoluminescence quantum yields were designed and synthesized in this study. Intense mirror-image circularly polarized luminescence signals were detected from both polymers in solution and film states, and high maximum external quantum efficiencies and brightness were achieved in solution-processed CP-PLEDs. Additionally, intense circularly polarized electroluminescence signals were observed from the CP-PLED devices fabricated with R-P and S-P.