One complaint often heard in relation to solar panels is that once installed on the roof they are often unpleasant to view. What was once ‘an eyesore’ is now about to change, after solar-energy engineers designed a new type of transparent solar cell able to turn windows into electricity generating panels while still letting home owners see outside.
A team at UCLA (University of California, Los Angeles) created an efficient style of polymer solar cell (PSC) able to produce natural energy by accepting infrared light, and to the naked eye, the cells appear almost transparent. Solar cells are manufactured in a photo-active plastic which is able to switch infrared light into electrical energy.
Due to the advantages offered in the latest PSCs over similar solar energy technologies, these developments have attracted a lot of attention. Researchers have started investigating the potential of using the polymer solar cells for a wide-range of applications. Certain devices might operate via a high-performance and see-through photovoltaic (PV) system, which might include integrated photovoltaics or PV chargers for mobile devices.
Previously, several different attempts where made to demonstrate a functional semi-transparent or visibly transparent polymer solar cell system. Unfortunately, these demonstrations often produced low device efficiency or low visible light transparency mainly due to high-performance transparent conductors and polymeric PV materials not deploying sufficiently in the device design and creation process.
A combined group of researchers at UCLA consisting of the Henry Samueli School of Engineering and Applied Science, the California NanoSystems Institute (CNSI), and the Department of Chemistry and Biochemistry have created a series of efficient, solution-processed, and see-through PSCs which feature a base of near-infrared light-responsive polymer and on top use a composite film of silver nanowire as the see-through electrode.
Fundamentally the near-infrared photoactive polymer is able to absorb a higher amount of near-infrared light although it isn’t as sensitive to a visible source of light, which balances transparency and solar performance in the region of visible wave-length.
A further development is the ability to construct the transparent conductor out of a combined titanium dioxide nanoparticles and silver nanowire, which has moved away from the more common use of opaque metal electrodes. Composite electrodes also give the option to manufacture the solar cells at a more attractive rate by a means of solution processing.
With this in effect, a 4% increase in the power-conversion efficiency for visibly transparent and solution-processed polymer solar cells is now seen as achievable.