"Black technology" is a new type of light-emitting diode which can illuminate and absorb external light source.

People can use their hands to touch the screen without touching the screen. Can it also use environmental lighting to automatically recharge? These "black technologies" are likely to be realized in the near future, thanks to a new type of light-emitting diode (LED) array that can emit light and absorb external light sources.

Researchers from the University of Illinois, Bana, Champaign and Dow electronics materials company in Marlborough, Massachusetts, recently published research in the American Journal of science. They showed a new type of colloidal semiconductor nanorod, which allows a single device to generate electroluminescence and generate electroluminescence while converting the electric energy into light energy.

These nanorods with a diameter of less than 5 nm consist of three semiconductor materials, one of which can emit and absorb visible light, and the other two control the charge flow in the first material. The three materials work together to enable the LED panel to induce external illumination and make brightness adjustment while emitting light.

Because this LED switches very quickly between the two functions of light and photosensitivity, the switch can not be recognized by the naked eye, so the display panel appears to be always bright. At the same time, unlike the current light sensor on mobile phones, the LED panel's photometry and dimming occur at pixel level. Therefore, it can adjust the brightness of the panel not only according to the external environment light source, but also induce the difference of fine light lines caused by fingers passing over the screen, thus allowing the gesture manipulation of the non touching screen.

Researchers also found that the LED can also absorb external light sources and convert it into electric current, which is similar to the function of solar panels. In the future, the mobile phone using the LED screen can also be charged by light and become a "self powered" cell phone.

In addition, the new LED display can also be used as a large parallel communication array to achieve large data exchange between them.

At present, researchers have successfully demonstrated the related functions with the new red LED array. They are trying to combine the red, blue and green three color LED to achieve color array display. At the same time, by adjusting the composition of nanorods, the absorptivity of LED can be improved.

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