Researchers at Linköping Univer­sity, Sweden, have developed a digital display screen where the LEDs themselves react to touch, light, fingerprints and the user’s pulse, among other things. Their results could be the start of a whole new generation of displays for phones, computers and tablets. “We’ve now shown that our design principle works. Our results show that there is great potential for a new genera­tion of digital displays where new advanced features can be created. From now on, it’s about improving the technology into a commer­cially viable product,” says Feng Gao from Linköping University.

Digital displays have become a cornerstone of almost all personal electronics. However, the most modern LCD and OLED screens on the market can only display information. To become a multi-function display that detects touch, finger­prints or changing lighting conditions, a variety of sensors are required that are layered on top of or around the display. The researchers have now developed a completely new type of display where all sensor functions are also found in the display’s LEDs without the need of any additional sensors. 

The LEDs are made of perovskite crystals. Its excellent ability of light absorption and emission is the key that enables the newly developed screen. In addition to the screen reacting to touch, light, finger­prints and the user’s pulse, the device can also be charged through the screen thanks to the perovskites’ ability to also act as solar cells. “Here's an example – your smartwatch screen is off most of the time. During the off-time of the screen, instead of displaying infor­mation, it can harvest light to charge your watch, signi­ficantly extending how long you can go between charges,” says Chunxiong Bao from the Nanjing University and previously a postdoc in Linköping.

For a screen to display all colours, there needs to be LEDs in three colours – red, green and blue – that glow with different intensity and thus produce thousands of different colours. The researchers have developed screens with perovskite LEDs in all three colours, paving the way for a screen that can display all colours within the visible light spectrum. But there are still many challenges to be solved before the screen is in everyone’s pocket. Zhongcheng Yuan from the University of Oxford and previously postdoc in Linköping believes that many of the problems will be solved within ten years:  “For instance, the service life of perovskite LEDs needs to be improved. At present, the screen only works for a few hours before the material becomes unstable, and the LEDs go out,” he says. (Source: Linköping U.)

Reference: C. Bao et al.: A multifunctional display based on photo-responsive perovskite light-emitting diodes, Nat. Elec., online 10 April 2024; DOI: 10.1038/s41928-024-01151-x

Link: Electronic and photonic materials, Dept. of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden