A tinted see-through coating has been developed that can generate electricity on glass windows from natural and artificial light via ultrasmall organic solar cells. SolarWindow, announced Wednesday by renewable energy technology developer New Energy Technologies Inc., uses an organic solar array made transparent through the use of conductive polymers that have the same electrical properties as that semiconductor workhorse material, silicon, yet boast a considerably better capacity to optically absorb photons from light and generate electricity, the company said. New Energy Technologies researchers applied ultrasmall working solar cells (less than one-fourth the size of a grain of rice, highlighted here as tiny dots) to see-through flexible plastic. (Photo: New Energy Technologies Inc.) Silicon wafers are expensive and brittle, two things that limit their commercial usability in solar cells. Other new-generation, lower-cost, flexible thin-film solar materials such as amorphous silicon, copper indium gallium selenide and cadmium telluride often require high-vacuum and high-temperature production techniques, and they are many times thicker than their cells, New Energy said. Those traits limit the application of such thin films primarily to stainless steel, an expensive substrate material with limited prospects of delivering transparency. New Energy’s cells measure less than one-fourth the size of a grain of rice, are fabricated using environmentally friendly hydrogen-carbon based materials and successfully produce electricity, according to a study published last year in the American Institute of Physics’ Journal of Renewable and Sustainable Energy, the company said. “I’m particularly impressed by the potential application of this technology in areas where direct exposure to sunlight is limited or unavailable, since these ultrasmall solar cells have demonstrated a special ability to generate electricity in both natural and artificial light conditions,” said Meetesh V. Patel, president and CEO of New Energy. Patel said the cells mark an important advance over early research and development of SolarWindow technology and address a number of commercial and technical limitations posed by conventional materials such as thin films, polycrystalline solar cells and silicon. While the majority of today’s solar cells can be installed only where direct sunlight is available, New Energy said its cells can generate electricity from the visible light spectrum found in sunlight or anywhere artificial systems emit visible light, such as fluorescent office lighting. New Energy said its technology allows for the fabrication of solar arrays on a range of substrate materials, such as glass, plastic and paper. Because the cells are made of natural polymers that can be dissolved into liquid for easy application, they don’t require expensive and complicated high-temperature or high-vacuum production techniques common to other solar coatings. The superior optical absorption properties of its ultrasmall solar cells enable development of an ultrathin film only 1/1000th the thickness of a human hair, or 1/10th of a micrometer, the company said. Conventional thin films are exponentially thicker, measuring several micrometers thick and inhibiting transparency, making them usable for producing a transparent solar window for homes, offices and other structures. New Energy said it is also developing MotionPower™, a roadway system for generating electricity by capturing the kinetic energy produced by moving vehicles. For more information, visit: www.newenergytechnologiesinc.com or view the study here.