A promising sputtering route for dense Cu2ZnSnS4 absorber films and their photovoltaic performance

Copper zinc tin sulfide (Cu2ZnSnS4, CZTS) is highly abundant in nature. It is an important absorber material for the development of low-cost and sustainable next-generation I-2-II-IV-VI4 thin-film solar cells because it has a the tunable direct band gap energy, inexpensive constituent elements, and a large absorption coefficient in the visible wavelength region. This work develops an efficient one-step vacuum-based approach to depositing CZTS films without the need to supply excess sulfur during/after deposition or to perform any post-sulfurization treatment. This one-step RF sputtering process produces CZTS films that are crystalline, phase-pure, dense, smooth, and continuous. Air Mass 1.5 G power conversion efficiencies of as high as 6% have been achieved with an antireflection coating, demonstrating that this new approach has great potential as a low-cost alternative for high-efficiency CZTS solar cell production. (C) 2014 Elsevier B.V. All rights reserved.