Earlier this week Spanish scientists at the Universitat Jaume I in Castelló’s Group of Photovoltaic and Optoelectronic Devices (DFO) and the University of Oxford published research in the journal Nano Letters showing that they are able to create a graphene and perovskite photovoltaic (PV) device that converts 15.6 percent of the sun’s energy into electricity. While the devices they used are less efficient then traditional silicon photovoltaics, which are already higher than 24 percent efficiency atSunPower, for instance, the graphene and perovskite used in the new devices use less and less expensive materials than in conventional—and even most thin-film PV modules.
Graphene, the single layer, 2-dimensional, electrically-conductive carbon wonder material is proving very interesting to thesolar industry as a potential material to make inexpensive solar PV. The material was only realized in 2004, using the “Sotch Tape” method even though it was theorized as early as 1947. Using that method tape is used to peel atom-thin layers of graphene from graphite. The method was developed by Andre Geim and Kostya Novoselov at Manchester University and they were awarded the Nobel Prize in Physics for the discovery in 2010.
Perovskite is also being looked at to make more efficient organic PV devices. This past fall researchers at Oxford University led by Henry Snaith, demonstrated perovskite PV cells with efficiencies over 15 percent. Snaith also contributed to the research in Spain and is a coauthor of the more recent paper. In the new device titanium oxide and graphene serve as the charge collector and perovskite absorbs the sunlight.
The resulting device, which has reached efficiency levels of 15.6 percent, is among the best for organic PV and essentially doubles the efficiency of record organic PV devices made with graphene as recently as 2012. “This efficiency exceeds that obtained by combining graphene with silicon, which is the photovoltaic material par excellence,” Asociación RUVID said. “This development is a new milestone for the progress of perovskite solar cells.”
The device is manufactured at low temperatures, which makes it less expensive to manufacture. “Researchers Eva Barea, Iván Mora and Juan Bisquert have explained that the new device consists of several layers processed at temperatures below 150°C,” according to Asociación RUVID. The low temperature process also means that the material could even be used in flexible PV devices.