Printed Solar Cell Using Nanostructured Ink

Period of Performance: 01/01/2007 - 12/31/2007


Phase 2 SBIR

Recipient Firm

Nanosolar, Inc.
5521 Hellyer Ave
San Jose, CA 95138
Principal Investigator
Firm POC


Solar cells made from a copper-indium-gallium-diselenide (CIGS) absorber layer are more than 100X better at absorbing light than an equivalent absorber layer made from silicon; consequently, CIGS solar cells can be constructed as thin film devices, with less material usage and potentially less cost than conventional silicon-based solar cells. A thinner absorber layer also results in less cell fragility, providing an opportunity to further reduce costs by reducing the packaging surrounding the solar cell. Unfortunately, the production of CIGS-based solar cells is not cost effective. The central challenge in cost-effectively constructing a large-area CIGS-based solar cell is to ensure that the elements of the CIGS layer are within a narrow stoichiometric ratio, as required for the resulting cell or module to be highly efficient. However, achieving precise stoichiometric composition over relatively large substrate areas is difficult when using traditional vacuum-based deposition processes. In this project, nanoparticulate CIGS precursor materials will be printed onto low-cost metal foil substrates, and then a rapid thermal processing will be performed to convert the nanoparticulate coating into a CIGS absorber layer. By locking the appropriate stochiometry into the nanoparticulate precursor material, spatial uniformity will be ensured in the coated layers. Printing at high speed and high throughout will minimize solar cell cost. Phase I demonstrated that an efficient solar cell could be coated onto a foil using the new printing technology. Phase II will construct these foil-based solar cells with increased power conversion efficiency. The chemical composition of the light-absorbing layer will be modified to improve the optoelectronic performance of the device, and the performance characteristics of the devices will be determined. Commercial Applications and Other Benefits as described by the awardee: Thin-film, low cost, solar cells could be deployed on the roofs of both residential homes and commercial buildings, as well as utility-scale solar power plants. Such deployment would decrease the current U.S. dependence on foreign energy sources.