American scientists from the University of Michigan have developed a new type of organic light-emitting diode (OLED) that can replace bulky and expensive night vision devices with lightweight and cheap glasses. The study was published in the scientific journal Nature Photonics (NatPhoton).
Modern night vision systems use image intensifiers that convert incoming near-infrared light into electrons, which are then accelerated through a vacuum into a thin disk containing hundreds of tiny channels. As the electrons pass through and collide with the channel walls, they release thousands of additional electrons and continue to hit a phosphor screen, which converts them into visible light.
The newly created OLED device also converts near-infrared light into visible light and amplifies it more than 100 times, but without the weight, high voltage, and bulky vacuum layer required by traditional image intensifiers. The researchers say the light can be amplified many times over by optimizing the device’s design.
The OLED device is equipped with a photon-absorbing layer less than a micron thick and a five-layer LED stack that converts electrons into visible light photons.
Because the device operates at a much lower voltage than a traditional image intensifier, it allows for the use of small power supplies.
Some of the photons reach the user's eye, but others flow back into the absorber layer, producing even more electrons. This chain reaction greatly increases the amount of light output.
Previous OLEDs could convert near-infrared light into visible light, but there was no gain, meaning one input photon produced one output photon.
According to the scientists, they have assembled an OLED device from ready-made materials. This means that the production of such devices will not require large expenses and can be easily scaled up.
