2009 R&D 100 Winner
Nanocrystal Solar Cells, developed by Lawrence Berkeley National Laboratory, Berkeley, Calif., and Solexant, San Jose, Calif., are ultra-thin solar cells based on dense nanocrystal films but without any organic materials. They have an efficiency potential of about 25%, matching that of silicon cells. In a nanocrystal solar cell, the two flat semiconductor layers are replaced by two types of nanocrystals whose light absorption and transport properties can be highly controlled in the design and synthesis of the material. To create the solar cells, the scientists developed a processing method to ensure good electrical conductivity, because the surfactant needed to make the nanocrystals is a poor electrical conductor. A sintering agent improves the particle-to-particle contact (in the lab, cadmium chloride was used) and permits the nanocrystals to carry out the electron transport effectively. An ultrathin insulating layer between the electrodes and the nanocrystals improves the junction performance. In another breakthrough, the scientists invented a composite nanorod nanocrystal that has the potential to enable solar cells with a higher theoretical efficiency limit.
Technology
Ultra-thin solar cells based on dense nanocrystal films
Developers
Lawrence Berkeley National Laboratory
Solexant
