New Solar Cells Use Perovskite to Turn Water into Energy

Solar Energy / Space & Other Applications

Date posted: 07/03/15

Tim Wogan reports that a new, highly efficient process for splitting water into hydrogen and oxygen has been demonstrated by researchers in Switzerland. The process combines a stable catalyst with a highly efficient perovskite solar cell. The perovskite solar cells do have a major drawback in that they breakdown after a few hours, but the researchers believe further advances in solar cell technology should take care of this problem. As the most abundant energy source on the planet, solar energy is extremely attractive for weaning the human race off fossil fuels, but making the switch is problematic. The energy captured has to be stored until it is needed and, as the most abundant solar resources are often where few people live, a way needs to be found to transport it to homes and businesses. One option is to use solar power to split water into hydrogen and oxygen. However, for this process to be efficient, two things are needed - a catalyst that can lower the activation energy barrier of splitting water enough to allow the reaction to proceed at a sufficient rate and a photovoltaic cell that provides sufficient voltage to surmount this energy barrier. Conventional solar cells use silicon as the photovoltaic material. As silicon is relatively cheap, the raw materials for such devices are inexpensive. However, silicon is an indirect band gap semiconductor, which makes it an inefficient absorber of light and means a thick layer is required. Such a thick layer cannot be deposited from solution so has to be cut from a wafer. This makes silicon solar cells quite expensive to assemble, although prices have dropped drastically with automation.