High-Contrast Black-and-White Switching via Reversible Copper Electrodeposition for Reflective Monotone Displays

Despite their low power consumption, commercial black-and-white reflective displays based on electrophoretic technology (i.e., electronic paper) suffer from limited brightness, contrast, and temperature tolerance. Here, this study presents an electrochemical display mechanism that addresses these limitations by integrating a light-scattering layer beneath a roughened indium tin oxide (ITO) electrode supporting reversible metal electrodeposition (RME). The scattering layer is composed of an interwoven titanium dioxide nanowire (TiO₂ NW) network, which provides efficient broadband light scattering to produce a white appearance, while simultaneously ensuring mechanical durability and ion transport. In contrast, a black state is achieved via copper electrodeposition onto the roughened ITO, where the resulting morphology induces strong broadband light absorption. The device exhibits brightness and contrast ratios exceeding those of current commercial e-readers by more than two-fold, along with stable switching across a wide temperature range (−5 °C to 55 °C). These results demonstrate a scalable electrochemical nanophotonic platform for next-generation black-and-white reflective displays.