This PFI: AIR Technology Translation project focuses on translating a research discovery on the use of aluminum for silicon surface texturing to fill the need for lower cost fabrication methods for silicon solar cells. The project will result in a prototype of a nanotextured silicon solar cell based on a one-step fabrication process. The one-step fabrication process is important because it addresses the need to develop sustainable, low cost solar manufacturing technology while maintaining high energy conversion efficiency. It has the following unique features: it uses aluminum in a dual role to form a p-n junction in crystalline silicon while simultaneously texturizing the silicon surface to reduce reflective losses; it reduces the number of processing steps required for solar cell fabrication, and it is based on earth abundant materials. These features provide several advantages including reduced process complexity, improved sustainability, and reduced cost when compared to the leading competing process which uses gold and silver to etch the silicon surface to fabricate nanotextured solar cells in this market space. The project engages Bandgap Engineering Inc., a leading developer of silicon nanowire solar cells, to provide device testing and evaluation capabilities, assist with cost model development and guide commercialization aspects in this technology translation effort from research discovery toward commercial reality. This project addresses the following technology gaps as it translates from research discovery toward commercial application. It will investigate the use of an aluminum thin film to simultaneously serve as the p-type diffusion source for junction formation and as a catalyst to mediate nanotexturing to form an anti-reflection layer on the surface. The effect of texturing morphology, i.e. nanowire versus nanocone, on the optical and photovoltaic properties of the devices will be studied. Methods to passivate the nanotextured surface will be developed to reduce efficiency losses resulting from surface recombination. A comprehensive cost model of the process will be developed to guide commercialization plans. The overall goal of the project is the development of a prototype solar cell based on the one-step process that exhibits a power conversion efficiency comparable to or higher than state-of-the-art nanotextured solar cells fabricated using gold/silver-induced etching. The potential economic impact is expected to be a reduction in the cost per Watt of crystalline silicon solar cells over the next decade, which will contribute to the U.S. competitiveness in renewable energy.
