Stanford researchers have developed a low cost photovoltaic material by using a scalable ion beam assisted deposition (IBAD) process to fabricate textured crystal silicon (c-Si) films on display glass. The inventors used a template seed layer of calcium fluoride (which has a close lattice match with silicon) to grow biaxially textured heteroepitaxial c-Si. This process controls the grain boundary alignment to improve microelectronic efficiency and performance. IBAD is a well-established room-temperature technique that is amenable to technically important substrates as well as process scaling. This technology could be used to coat large area and long length substrates with high performance c-Si to help achieve low cost solar cells. Stage of Research: The inventors have fabricated a proof-of-concept epitaxial film c-Si solar cell with an open circuit voltage of 375 mV.
1) High performance material - polycrystalline thin films of silicon with highly oriented low-angle boundaries have reduced dislocation density and increased carrier lifetime 2) Scalable 3) IBAD fabrication can be used to coat large area substrates with additional features