Physicists have invented a light-sensitive device that can generate binary optical signals resembling binary digits (1 and 0), making it potentially useful for developing light-based computing systems1. Being light-sensitive, it could also be used to enhance the efficiency of solar cells.

In separate recent experiments, researchers had made a number of light detectors that were capable of generating binary optical signals. These devices, however, generated optical signals only in the presence of ultraviolet and visible light.

In search of a device that is sensitive to a wide range of light, scientists from CSIR-National Physical Laboratory in New Delhi, India, led by Prabir Pal and Suraj P. Khanna, fabricated the light-sensitive device by embedding nanosheets of graphitic carbon-nitride in silicon. They then tested its light sensitivity by exposing it to a wide range of light.

The device displayed excellent light sensitivity to the entire spectrum of light, including ultraviolet, visible and near-infrared light. It retained its good light sensitivity up to the near-infrared region of light. Exposure to light led to a change in the current from positive to negative at small externally applied voltage. Positive and negative current are equivalent to binary digits 1 and 0, respectively.

This successfully demonstrates the ability of the device to function as an optical binary switch at room temperature. Being a highly sensitive light detector, it could harness its own power from light, shunning the need for connecting it to any external energy source.