Transparent Light-Harnessing Material
Detail of conjugated polymer (PPV) honeycomb by scanning electron microscope. Photo: Courtesy of the Brookhaven National Laboratory.
The solar-harvesting window is one of the original wish list items for BIPVs, or building integrated photovoltaics. The notion is that one device can take advantage of the cooperative pairing of functional requirements for thermal performance and renewable energy. Glazing that receives direct sunlight is subject to solar heat gain, and protective strategies such as ceramic fritting, tinting, or the application of reflective films are currently used in order to reduce the intensity of solar radiation. Because solar photovoltaics perform optimally in direct sunlight, PV films may be strategically applied to exposed glazing in lieu of conventional sun-blocking materials. This arrangement sounds ideal, except for the difficulties of integrating PV films successfully without excessively blocking light or views.
Recently, researchers at the U.S. Department of Energy (DOE) Brookhaven National Laboratory and the Los Alamos National Laboratory developed a new carbon-based light-harvesting technology that is also transparent. Based on the Buckyball structure of 60 carbon atoms, the hexagonal fullerene cells can be deposited in thin films that are scalable to industrial-level production.
According to Brookhaven lead scientist Mircea Cotlet, “Our work provides a deeper understanding of the optical properties of the honeycomb structure. The next step will be to use these honeycomb thin films to fabricate transparent and flexible organic solar cells and other devices.” Cotlet adds: “Imagine a house with windows made of this kind of material, which, combined with a solar roof, would cut its electricity costs significantly. This is pretty exciting.”