Photodetectors are also called photoelectric sensors, which can convert light energy into electrical signals to complete tasks such as opening automatic sliding doors and automatically adjusting the brightness of the mobile phone screen under different lighting conditions. Now, according to foreign media reports, researchers at Penn State University in the United States seek to further expand the use of photodetectors by combining photodetectors with durable Gorilla glass. Gorilla glass is a product of Corning, a material used to make smartphone screens.

Ordinary glass becomes a photodetector (photo source: Pennsylvania State University)

The integration of photodetectors and Gorilla glass may promote the commercial development of “smart glass” or glass equipped with automatic sensing capabilities. According to the researchers, smart glass has many applications, such as imaging and advanced robotics.

Saptarshi Das, assistant professor and principal researcher of the Department of Engineering Science and Mechanics (ESM), said: “There are two problems that need to be solved when building and scaling photodetectors on glass. Degradation; secondly, it is necessary to ensure that the photodetector uses the least energy to operate on the glass.”

In order to overcome the first challenge, Das collaborated with Joseph R. Nasr, a doctoral student in the ESM department, and determined that the chemical compound molybdenum disulfide is the best material for coating glass.

Then, Professor Joshua Robinson of the Department of Materials Science and Engineering (MatSE) and Nicholas Simonson, a PhD student in the Department of MatSE, used a chemical reactor at 600 degrees Celsius (the temperature is low enough to not degrade Gorilla glass) to fuse the compound and glass together. Next, the researchers used traditional electron beam lithography tools to turn the glass and coating into a photodetector.

Nasr said: “Then we tested this glass with green LED lighting. Unlike the laser lighting commonly used in similar optoelectronics research, the green LED mimics a more natural light source.”

The ultra-thin body of the molybdenum disulfide photodetector allows it to better control static electricity and ensure that it can operate at low power, which is a key requirement for future smart glass technology.

Researchers said that if commercialized, smart glass may promote technological progress in a wide range of industries such as manufacturing, civil infrastructure, energy, healthcare, transportation, and aerospace engineering. This technology can be used for biomedical imaging, security monitoring, environmental sensors, optical communications, night vision, motion detection, and collision avoidance systems for autonomous vehicles and robots.

Robinson said: “When driving at night, the smart glass on the car’s windshield can use this technology to automatically change its opacity to adapt to the high beams of oncoming vehicles. The new Boeing 757 can be placed on the windows of the pilot and passengers. Use this glass to automatically dim the sun.”