Alternative Thin Film Semiconductor Materials

The solar energy industry is facing an unprecedented growth opportunity with a severely constrained raw materials supply. The current reliance on toxic or constrained materials in solar cells can be reduced in two primary ways: increased conversion efficiency with existing materials or substitution by alternative materials. This project will continue the development of a proprietary substrate technology that provides increased conversion efficiency for existing thin-film materials such as CdTe. The innovation combines the highest-efficiency solar cell technology, normally produced from single crystal wafers, with the low cost of thin film processes, by combining a biaxially-textured metal-foil template with a surface suitable for the roll-to-roll production of high-efficiency photovoltaic films. Silicon, CdTe, and compound semiconducting films with near-single crystal performance can be produced on such a template. In Phase I, technical feasibility will be shown by demonstrating: (1) the growth of flexible, near single crystal films, and (2) a functioning Si, CdTe or III-V photovoltaic cell on a qualified metal foil template. The ultimate objective is a multijunction photovoltaic, produced on a freestanding metal foil, with conversion efficiency approaching 30% and cost below $0.10/kW-h. Commercial Applications and other Benefits as described by the awardee: The production of III-V photovoltaics on thin, flexible metal foil should result in unparalleled power per unit mass, enabling a new capability for mobile, remote power in ground, air, and space applications. The broad adoption of solar power would significantly reduce dependence on fossil fuels and reduce greenhouse gas emissions.