DARPA funded research at the University of Florida (Gainesville, FL) has adapted technology utilized in OLED displays to create a thin film that converts infrared light into visible light. The technology has the potential to allow integration of inexpensive night vision capability into a variety of consumer products.
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Leading the research team is Franky So, an Associate Professor in the Organic Electronic Materials and Devices Laboratory, which is a part of the Materials Science and Engineering Department in the College of Engineering. The research reported in this article recently appeared in the journal Advanced Materials.
Existing night vision devices typically incorporate an internal vacuum and require high voltage to operate. As a result, they are usually both bulky and heavy. So believes that a full size device based on the new technology could weigh as little as 10 grams, be only a few microns thick and run on a small battery.
In the new device, infrared light enters the film and interacts with the first of seven separate layers. The interaction generates a small electrical charge. In the remaining layers, the application of three to five volts provides additional electrical energy that serves to amplify the signal. The image output by the film is green light, which is similar to the color of light from conventional night vision goggles.
In the past, so-called near infrared up-conversion devices were typically based on heterojunction structures composed of inorganic semiconductors, whose efficiency is quite low. More recently, near infrared-to-visible light up-conversion devices were created based on the use of an inorganic light emitting diode in conjunction with an inorganic photodetector. These devices also demonstrated a low external conversion efficiency of about 0.3%. In addition, inorganic up-conversion devices were expected to be expensive to fabricate for large area applications.
At this time, both high-efficiency Organic LEDs and high-efficiency organic photodetectors have been developed. As a result, all organic up-conversion devices can be created by combining these technologies in one device. Because these materials are compatible with plastic substrates that are lightweight, rugged and flexible, up-conversion devices constructed entirely of organic materials have the potential to enable a range of applications that cannot otherwise be realized.
Beyond those for the military, potential applications for the new technology include night vision eyeglasses. Integrated into a car windshield, the technology could make pedestrians easier to see. So also reports that there are plans to create cell phones that not only can "see" at night but that can also visualize heat patterns. Such a cell phone could, for example, be used to remotely take the temperature of a patient.
At this time, only a proof of concept night vision device has been fabricated. None-the-less, optimism dominates and the researchers believe that the concept can be turned into a useable device within 18 months. -Arthur Berman