White Light-Emitting Electrochemical Cells: Progress, Challenges, and Outlook

Abstract

White light-emitting electrochemical cells (LECs) have emerged as a distinctive class of solid-state light sources that combine simplified device architectures with solution-processable materials and intrinsically balanced charge injection enabled by electrochemical doping. In contrast to conventional white organic light-emitting diodes, white LECs can achieve broadband emission using single-layer active materials and air-stable electrodes, offering compelling advantages for low-cost display and lighting technologies. This review provides a comprehensive overview of recent progress in white LECs, covering key material platforms including conjugated polymers, ionic transition metal complexes, small molecules, quantum dots, and perovskites. Particular emphasis is placed on the fundamental optical and electrical mechanisms governing white-light generation, including single-emitter strategies, host–guest architectures and hybrid device configurations. Device engineering strategies for managing carrier transport, microcavity effect, optical filtering, color conversion layers, and optical out-coupling are also critically discussed in relation to device efficiency and spectral stability. Despite remarkable advances in device performance, challenges remain in achieving simultaneously high brightness, device efficiency, and long-term stability. Finally, future opportunities for advancing white LECs through materials innovation and integrated electrical–optical design are outlined, highlighting their potential as a versatile platform for next-generation solid-state lighting.