Rational Design of Circularly Polarized Luminescent Molecular Structures Toward NIR and Single Molecule White Light Emission

Single-molecule white-light and near-infrared circularly polarized luminescent materials are effective complements to the demonstrated enhancements of visible emission in the high contrast 3D images or organic light-emitting diodes. In this contribution, two binaphthalene-containing luminogenic enantiomers (BIT or BITM) with aggregation-induced emission are synthesized which exhibit circularly polarized luminescence in solution with dissymmetry factors of +/- 5.0 x 10-3 and +/- 4.8 x 10-3, respectively. Additionally, the dual-fluorescence spectra of single-molecule white emission (CIE: 0.33, 0.34) in toluene solution are observed with (R)/(S)-BIT in low polarity solvent originating from locally excited and twisted intramolecular charge-transfer emission. While (R)/(S)-BITM only shows single NIR luminescence with peaks at 720 nm in powder state. The nondoped OLEDs exhibit high maximum external quantum efficiencies of up to 4.2% with small efficiency roll-off and NIR electroluminescence peak at 709 nm. By employing a simple design approach that combines an axial chiral binaphthol unit as an electron-regulating group with a deep-red chromophore, a single-molecule CPWL has not only successfully engineered but has also accomplished the NIR-CPL performance.image