Achieving Over 20% EQE in White Light-Emitting Electrochemical Cells via Quantum-Dot Color Conversion Layers

Solid-state light-emitting electrochemical cells (LECs) feature a simple design, low operating voltage, and insensitivity to electrode work functions, making them ideal for low-cost display and lighting applications. However, producing stable and efficient white LECs remains challenging. In this study, blue LECs paired with red or yellow/red quantum-dot (QD) color conversion layers (CCLs) are shown to emit stable and efficient white light. Specifically, blue LECs with red QD CCLs achieve an external quantum efficiency (EQE) of over 20%, while those with yellow/red QD CCLs produce white light with a low correlated color temperature $(< 2500\mathrm{K})$, a high color rendering index (up to 93), and a peak EQE exceeding 16%. These results demonstrate that partial energy down-conversion from blue LECs to QD CCLs can yield promising white light sources for lighting applications.