One display for everything: touchscreen, solar cell, fingerprint sensor, heart rate monitor

An LED converts electricity into light. A solar cell goes the opposite way. Incident light is converted into electricity. Put simply, they are two sides of the same coin.

It is precisely this fact that researchers at Linköping University in Sweden are exploiting to develop the Swiss army knife of displays. Because where light can be emitted and captured, there are countless other possible applications.

Basically, the display consists of self-illuminating cells like an OLED display. These use perovskite crystals, from which the name PeLED is derived. Modern solar cells, although still in the development stage, also use this material due to its high efficiency and light transmission.

It can convert light into electricity at a high level, but can also be used as a green, blue and red LED to display content on a screen as usual.

Because information is available for each individual LED as to whether and how much electricity is converted from light, the entire display acts as an environmental sensor and individual LEDs mimic the touch sensitivity of a touchscreen.

Although the cells are not really touch-sensitive, they can recognize the finest differences even in weak ambient light or even through light emitted by the device itself. This means that every area that is currently covered by a finger can be precisely assigned and control works just like on a modern smartphone.

In addition, the technology can even be used to recognize fingerprints due to the fine resolution, so that biometric unlocking is also included. And because the developed multifunction LEDs can also emit infrared light, the pulse on the wrist can also be measured.

This means that a smartwatch equipped with this display, which is currently only available as a prototype, could be designed in a completely different way. In particular, a whole range of sensors are no longer needed, as the screen takes over almost all tasks. And the inconvenience of charging can also be reduced because additional power is obtained from the ambient light.

In theory at least, the principle seems to be just too perfect for mobile devices. Now the researchers just need to incorporate something with AI and success is assured.