Programmable Circularly Polarized Electroluminescence Through Stereocontrol of Chiral Liquid‐Crystalline Co‐Assemblies

Two chiral inducers (S-/R-1 and S-/R-2) with varying binaphthalene dihedral angles were selected with achiral liquid crystalline polymer PyP to form chiral co-assemblies. As the dihedral angle of the binaphthyl inducer decreased from obtuse to acute angle, the resulting co-assemblies (S-/R-2)_0.1-(PyP)_0.9 could emit inverted and amplified circularly polarized electroluminescence with a |g _EL| value up to 0.18 compared with (S-/R-1)_0.1-(PyP)_0.9.

Abstract

Circularly polarized organic light-emitting diodes (CP-OLEDs) are essential to prospective 3D displays and advanced polarized lighting systems. The rational design of programmable circularly polarized electroluminescence (CP-EL) materials with a large electroluminescence dissymmetry factor (g _EL) remains a great challenge and is still in its preliminary exploration phase. In this work, two aggregation induced emission active (AIE-active) chiral inducers with different dihedral angles of binaphthalene (S-/R-1 and S-/R-2) and achiral acrylate-based liquid crystalline polymer (LCP) (PyP) were chosed to construct chiral co-assemblies through an intermolecular chirality induction mechanism. Interestingly, as the dihedral angle of the AIE-active binaphthyl inducer decreased from obtuse to acute angle, the resulting co-assemblies (S-/R-2-PyP) could emit inverted and amplified CP-EL signals compared with S-/R-1-PyP after annealing. Significantly, the (S-/R-2)_0.1-(PyP)_0.9-based CP-OLEDs displayed remarkable blue CP-EL (λ _EL = 480 nm, L _max = 14860 cd m⁻²) with a record |g _EL| value of up to 0.18 in chiral co-assembled CP-OLEDs to date. This work describes the first observation of dynamic CP-EL with tunable signal direction and intensity through stereocontrol of AIE-active chiral inducers in LCP co-assembled films, providing a valuable guidance for realizing programmable CP-EL.

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