Researchers from KIT have developed sunglasses with colored, semi-transparent solar cells on the lenses that supply a microprocessor and two displays with electric power. This technology paves the way for future applications, like the integration of organic solar cells into windows or overhead glazing.
Organic solar cells are flexible, transparent, lightweight and can be manufactured in many shapes and colors. This makes them suitable for many specialized applications that cannot use conventional silicon solar cells.
The “smart” solar glasses were designed as part of a case study by Dr. Alexander Colsmann, Head of Organic Photovoltaics Group at KIT’s Light Technology Institute (LTI), and his team at KIT. The glasses are self-powered in order to measure and display solar illumination intensity and ambient temperature. The solar cell lenses fit into a commercial frame, with a thickness of 1.6 millimeters and a weight of about 6 grams, comparable to traditional sunglasses. The microprocessor and two small displays are integrated into the temple part of the sunglasses. The solar glasses work in indoor as well as outdoor environments, as long as there is an illumination of at least 500 lux, the usual light of an office or living space. Even in lower illumination areas, the smart lenses generate 200 milliwatts of electric power, which is enough to operate devices like a hearing aid or step counter.
"The solar glasses we developed are an example of how organic solar cells may be employed in applications that would not be feasible with conventional photovoltaics," says Ph.D. student Dominik Landerer, who contributed to the development of the solar glasses at the Material Research Center for Energy Systems of KIT. Solar cells based on hydrocarbons are exciting to engineers because of their mechanical flexibility, and they have the opportunity to adapt color, transparency, shape and size to the desired application.
Another field of application is the integration of solar cells into buildings. The glass windows of high-rise buildings are often shaded, and organic solar modules would work for transforming the light absorbed through these windows into electric power. Colsmann hopes to use this technology to coat large surfaces with organic solar cells using reel-to-reel technology.
The study on this research, “Solar Glasses: A Case Study on Semitransparent Organic Solar Cells for Self-Powered, Smart Wearable Devices”, was published in the Energy Technology journal.