Researchers have developed a colour e-paper technology that displays high-resolution images and video while using very low energy. This innovation could pave the way for more efficient screens in future smartphones and devices. The technique relies on tungsten oxide nanodiscs to achieve vibrant colours without constant power.
A team led by Kunli Xiong at the University of Uppsala in Sweden has created a new type of colour e-paper that overcomes longstanding limitations in refresh rates and energy efficiency. Traditional e-paper screens, which use tiny molecules to form images rather than emitting light like LED displays, were previously confined to black-and-white or struggled with colour video due to slow refresh times.
The breakthrough involves pixels constructed from tungsten oxide nanodiscs, each approximately 560 nanometres in size. This design yields a resolution of 25,000 pixels per inch (PPI), far surpassing the hundreds of PPI typical in smartphones. By varying the sizes and spacings of the nanodiscs, the screen reflects specific bands of light to produce a full range of colours. A brief electrical pulse introduces an ion into each disc to adjust brightness, and once set, the colour persists without ongoing power, minimising energy consumption.
The prototype measures just 1.9 millimetres by 1.4 millimetres—about 1/4000th the area of a standard smartphone display—and successfully rendered a 4300-by-700 pixel crop of Gustav Klimt’s painting The Kiss. It refreshes approximately every 40 milliseconds, enabling smooth video playback. Energy usage stands at around 1.7 milliwatts per square centimetre for video and 0.5 milliwatts per square centimetre for static images.
"What I like about this work is it is both fast enough to support video, while keeping energy use to a minimum. That’s because once elements are switched, they stay switched without having to refresh them," says Jeremy Baumberg at the University of Cambridge.
The research appears in Nature (DOI: 10.1038/s41586-025-09642-3), highlighting potential applications in low-power devices.