Researchers have designed new "smart" solar sunglasses incorporating semi-transparent organic solar cells that can generate electric power enough to operate devices such as hearing aids.
The invention can pave the way for other future applications such as the integration of organic solar cells into windows or overhead glazing, the researchers said.
"We bring solar power to places where other solar technologies fail," said Alexander Colsmann, from the Karlsruhe Institute of Technology (KIT) in Germany.
"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," added Dominik Landerer, doctoral student at the KIT.
The solar cell lenses, perfectly fitted to a commercial frame, have a thickness of approximately 1.6 mm and weigh about six grams - just like the lenses of traditional sunglasses.
A microprocessor and two small displays are integrated into the temples of the solar glasses, which help these "smart" glasses to be self-powered to measure the solar illumination intensity and ambient temperature and view as bar graphs.
These solar glasses also work in indoor environments under illumination down to 500 lux - the usual illumination of an office or a living area.
Under these conditions, each of the "smart" lenses still generates 200 milliwatt of electric power - enough to operate devices such as a hearing aid or a step counter.
The solar cells, based on hydrocarbons, are very exciting devices due to their mechanical flexibility and the opportunity to adapt their colour, transparency, shape, and size to the desired application, Landerer added, in the paper detailed in the Energy Technology journal.
These solar glasses can also be integrated into the glass facades of high-rise buildings. Organic solar modules can be used for transforming the absorbed light into electric power, the study added.