Efficient circularly polarized electroluminescence from achiral luminescent materials

Circularly polarized electroluminescence (CP-EL) with a defined color is generally produced in organic light-emitting diodes (OLEDs) based on CP luminescent (CPL) materials with similar colors. Such kind of many-to-many relationship requires numerous new CPL materials to fabricate CP-OLEDs because the well-developed achiral luminescent materials are rarely considered to be capable of directly producing CP-EL. Herein, the one-to-many strategy is proposed for CP-EL by employing high-performance near ultraviolet CPL materials to sensitize achiral luminescent materials. These newly developed near ultraviolet CPL materials have excellent photoluminescence (PL) quantum yields and good CPL dissymmetry factors, and can induce efficient blue to red CP-PL for achiral fluorescence, phosphorescence, thermally activated delayed fluorescence (TADF) and multi-resonance (MR) TADF materials. Efficient near ultraviolet CP-EL with the best external quantum efficiencies (ηexts) of 9.0% at 404 nm and extremely small efficiency roll-offs are achieved by using them as emitters for CP-OLEDs. By adopting them as hosts or sensitizers, commercially available yellow-orange achiral phosphorescence, TADF and MR-TADF materials can generate strong CP-EL, with absolute dissymmetry factors and outstanding ηexts of up to 2.87 × 10−3 and 30.8%, respectively, which are the state-of-the-art CP-EL performances reported so far, demonstrating a simple and universal avenue towards efficient CP-EL.