More efficient solar cells

As the search continues for an inexpensive, efficient solar-energy-conversion device, conventional photovoltaic devices are under increasing competition from 'wet' photoelectrochemical cells. Photoelectrochemical cells are relatively simple (and potentially inexpensive) to construct, because they require merely the immersion of the desired photoactive solid into an ionically conducting liquid. On page 330, a team led by S. Licht describe how in certain cases it is possible to achieve the desirable combination of high efficiency and low corrosion rates by manipulating the composition of the conducting liquid. With their approach, Licht et al. demonstrate that cadmium selenide electrodes can be coaxed into stable operation in an aqueous solution with an overall energy-conversion efficiency of 17 per cent.