SusChEM: Synthesis and Characterization of Pyrite Thin Films - Towards Sustainable Photovoltaics

Technical Description: Understanding and controlling doping in pyrite iron disulfide films is a major challenge that would have significant impact towards realization of a sustainable, inexpensive, high-efficiency thin-film solar cell technology. To this end, the overarching goal of this research project is to understand and control the electronic properties of thin iron disulfide films to such an extent that fabrication of homojunction p-n solar cells is enabled. In addition to understanding electronic transport mechanisms, the research activities focus on establishing control over the charge carrier type and density by executing a detailed and systematic examination of the influence of sulfur stoichiometry and substitutional doping on the electronic properties of iron disulfide. The research team uses reactive sputtering and ex-situ sulfidation of iron films, as well as single crystal growth, to synthesize iron disulfide. The systematic research of film and crystal synthesis is accompanied by a battery of complementary characterization techniques designed to provide feedback and guidance on the effects of synthesis conditions on film properties and, in particular, on carrier densities and mobilities.

Non-technical Description: Achieving sustainable solar-to-electric energy conversion with solar cells made from inexpensive, abundant and non-toxic materials is one of the most challenging problems of the twenty-first century. While the materials dominating the current solar cell market each offer unique advantages, none are able to satisfy all of these requirements. Pyrite structure iron disulfide has been acknowledged as a sustainable material with great potential to satisfy these criteria, replacing critical materials used in the current technologies. However, control over the electronic properties of this material, which is required for efficient solar cells, has not yet been achieved. This research project aims to utilize multiple synthesis and processing strategies to achieve unprecedented control over the electronic properties in iron disulfide. This research is integrated into outreach and educational activities through interactions with the Science Museum of Minnesota, via mentoring of undergraduate students, particularly those from under-represented groups, via mentoring of high school teachers for developing science content for their classrooms, and through creation and delivery of an interactive presentation on Sustainable Materials and Chemistry designed to augment the science curriculum in the eighth grade Minneapolis Public Schools system.