Scientists took inspiration from mammalian eyes to create the fastest and most responsive flexible silicon phototransistor in history.
This incredible new phototransistor could have applications in a wide range of devices such as digital cameras, smoke detectors, and satellites, the University of Wisconsin-Madison reported. The breakthrough could help make these types of devices sleeker, and boost the speed and quality of videos.
Phototransistors behave in a similar fashion to the human eye because they sense and collect light before converting it into an electric charge based on its intensity and wavelength. The eyes transmit the electrical impulse images to the brain, but in the case of a digital camera, electrical charge becomes the long string of 1s and 0s that make up the digital image. Most phototransistors are created on a flat rigid surface, but this new flexible device can more closely mimic the eyes of mammals.
"We actually can make the curve any shape we like to fit the optical system," said Zhenqiang "Jack" Ma, professor of electrical and computer engineering. "Currently, there's no easy way to do that."
The new phototransistor was created with an innovative "flip transistor" method. In the final step of this fabrication method, the researchers invert the finished phototransistor onto a plastic substrate so that a reflective material is on the bottom.
"In this structure - unlike other photodetectors - light absorption in an ultrathin silicon layer can be much more efficient because light is not blocked by any metal layers or other materials," Ma said.
Electrodes are placed under the phototransistor's silicon nanomembrane layer, allowing the metal and electrode to easily improve light absorption.
"This demonstration shows great potential in high-performance and flexible photodetection systems," said Ma, whose work was supported by the U.S. Air Force. "It shows the capabilities of high-sensitivity photodetection and stable performance under bending conditions, which have never been achieved at the same time."
The findings were published in a recent edition of the journal Advanced Optical Materials.
