BRIGE: CZTS Thin-Films and Solar Cells by Liquid-Based Techniques

Southern Polytechnic State University, Marietta GA

Investigators

Abstract

Intellectual Merit: The research objective of this BRIGE award is the fundamental developmental of Cu2ZnSnS4 (CZTS) thin films and solar cells by non-vacuum, liquid-based techniques. Expensive materials and processes limit the potential for future long term cost reductions in photovoltaics. Thin film polycrystalline low cost solar cells have emerged as a significant step in reducing the materials cost in photovoltaics. CZTS has recently emerged as one of the most promising absorber layer materials for low-cost thin-film solar cells, providing both an economical and green solution to the current thin-film technologies, consisting of abundant, low-cost, non-toxic elements. CZTS has a suitable optical band gap of ~1.5 eV and a large optical absorption coefficient of over 104 cm-1. This research will develop a solution-particle (hybrid slurry) approach using the CTZS constituents to fabricate the CZTS thin films. Characterization and analysis of the thin films will focus on the composition ratios with the objective of growing Cu-poor and Zn-rich CZTS thin films, the formation of a stoichiometric compound, growth of large grains, and a stable crystal structure. High residual stress in the thin films can trigger significant undesirable consequences including deformation, fracture, delamination and device failure. This research will perform CZTS thin film adhesion and stress analysis and employ techniques and mechanisms that alleviate stress, promote adhesion and improve the overall quality of the films. This research will establish a relation between thin film deposition conditions, and electrical, optical and structural properties of CZTS thin films that will enable the fabrication of high efficiency solar cell devices. Broader Impact: The proposed research of CZTS thin films enabling high efficiency solar cell devices will broaden the participation of underrepresented groups in an emergent area of national need ? alternative renewable energy sources. This project will implement educational and outreach activities including research experiences for undergraduate and graduate students. The outcomes of this research will be integrated into a new course, ?Fundamentals of Solar Power and Renewable Energy?. This course will be developed during the proposed project and offered to students in all science, technology, engineering and mathematics (STEM) disciplines. This research will be integrated into the outreach and educational activities beyond training of undergraduate and graduate students. Early awareness outreach programs that stimulate interest in science, engineering and solar energy will be developed. Outreach activities will include solar energy summer camps and programs targeted to young girls in middle school. In addition to supporting and mentoring undergraduate researchers, a postdoctoral researcher will be supported and mentored.