Chiral Thermally Activated Delayed Fluorescence Materials Based on R/S-N2,N2′-Diphenyl-[1,1′-binaphthalene]-2,2′diamine Donor with Narrow Emission Spectra for Highly Efficient Circularly Polarized Electroluminescence

In this study, two pairs of chiral thermally activated delayed fluorescence (TADF) materials enabling circularly polarized luminescence (CPL) named R/S-p-BAMCN (rod-shape) and R/S-o-BAMCN (helix-shape) are prepared based on a new pair of chiral donor (D*), R/S-N-2, N-2'-diphenyl[1,1'-binaphthalene]-2,2'-diamine (R/S-BAM), and two cyano (CN) acceptors. Due to the rigid molecular structure and special intramolecular arrangement, the chiral TADF materials show high photoluminescence quantum efficiency (up to 0.86) with narrow full-width at half-maximum (38 nm in cyclohexane, 51 nm in toluene) and photoluminescence dissymmetry factor (vertical bar g(PL)vertical bar) up to 5.3 x 10(-3). Particularly, the circularly polarized OLEDs (CP-OLEDs) with rod-shaped R/S-p-BAMCN as the emitter show high device performances with the maximum external quantum efficiency nearing 28%. Meanwhile, the semi-transparent CP-OLEDs based on helix-shaped R/S-o-BAMCN exhibit obvious circularly polarized electroluminescence (CPEL) properties with the electroluminescence vertical bar g(EL)vertical bar factors around 4.6 x 10(-3). The strategy of rigid D*-A-D* structure with special arrangement of chiral donor provides a direct way to obtain efficient CP-TADF materials with narrow emission spectra and promising CPL properties for better CPEL performance.

Automated summary

Novel chiral TADF materials with high photoluminescence quantum efficiency and narrow emission spectra were prepared and showed promising performance in OLEDs, indicating potential for improving electroluminescence properties.