Researchers at the University of Wisconsin-Madison have developed the world’s fastest and most responsive flexible silicon phototransistor. The innovation could dramatically improve the performance of a variety of products such as digital cameras, smoke detectors, night vision goggles, satellites, surveillance systems, and other products that rely on electronic light sensors.
It improves the quality of videos and photos
Researchers Zhenqiang Ma and Jung-Hun Seo said the high-performance phototransistor far outperforms every previous flexible phototransistor on all the parameters, including response time and sensitivity. A major feature of the new transistor is its small size, which reduces the bulkiness and increases the acquisition speed and quality of videos and still images.
Ma said the new phototransistor is capable of high-sensitivity photodetection and shows stable performance under high bending conditions. These two have never been achieved at the same time. Findings of the study were published in the journal Advanced Optical Materials. Another important feature of the new transistor is that light absorption in an ultrathin silicon layer is much more efficient than metal or other materials because the light is not blocked by any layer of material.
The phototransistor works like mammals’ eyes
The project was inspired by mammalian eyes. So, the new phototransistor collects light and transforms it into an electrical impulse. Just like the pulse is transported by the brain’s nerves in mammals, the electric charge in this transistor turns into binary code that is converted into a digital image. It could improve digital cameras to deliver higher definition and clearer images even in low-light conditions.
Most phototransistors are fabricated on rigid surface, so they are flat. But the newly discovered one is flexible, allowing it to mimic the behavior of mammalian eyes. It is capable of sensing weak light. Scientists attached electrodes under the transistor’s silicon nanomembrane layer. The electrodes and the metal layer individually act as reflector and enhance absorption of light, eliminating the need for an external amplifier.