Solar-powered sunglasses tell you the temperature and more

German researchers have added organic solar cells to sunglasses, creating the first in what could be a new generation of consumer-oriented mobile applications with integrated solar technology.

Based on hydrocarbons, organic solar cells are flexible, transparent and lightweight. With the ability to adapt their colour, transparency, shape and size to the desired application, they are suitable for use in a variety of situations where conventional silicon solar cells would not be practical.

With this in mind, Dr Alexander Colsmann and his team at KIT’s Light Technology Institute (LTI) designed ‘smart’ sunglasses featuring coloured, semitransparent solar cells that are self-powered to measure and display solar illumination intensity and ambient temperature. Their research has been published in the journal Energy Technology.

The solar cell lenses, well fitted to a commercial frame, have a thickness of approximately 1.6 mm and weigh about 6 g — just like the lenses of traditional sunglasses. A microprocessor and the two small displays, integrated into the temples of the solar glasses, show the illumination intensity and the ambient temperature as bar graphs.

The solar glasses also work in indoor environments under illumination down to 500 lux, which is the usual illumination of an office or a living area. Under these conditions, each of the lenses still generates 200 mW of electric power — enough to operate devices such as a hearing aid or a step counter.

Another possible application, according to Dr Colsmann, is the integration of solar cells into buildings. Since the glass facades of high-rise buildings must often be shaded, organic solar modules could be used for transforming the absorbed light into electric power. A further application could be to coat large surfaces with organic solar cells using reel-to-reel technology.

Image caption: These solar glasses with lens-fitted, semitransparent organic solar cells supply two sensors and electronics in the temples with electric power. Image credit: KIT.