Journal of Nanomedicine & Nanotechnology

Mechanochemically assisted synthesis of kesterite Cu2ZnSnS4 nanopowders for photovoltaic applications via copper alloys formation

Nano World Summit: Current and Future Perspectives

June 06-07, 2018 | Philadelphia, USA

Jerzy F Janik, Katarzyna Kapusta and Mariusz Drygas

AGH University of Science and Technology, Poland

Posters & Accepted Abstracts: J Nanomed Nanotechnol

Abstract:

The mechanochemical synthesis dwells on reactions induced in substrate mixtures under high energy ball milling conditions such as up to 900-1000 rpm speeds of planetary ball mills and use of extremely hard grinding balls. Starting from suitable mixtures of all four elements, we have successfully explored such a process for the preparation of nanopowders of semiconducting kesterite Cu2ZnSnS4 â?? prospective material for photovoltaics. Herein, described is a modification of the process in which, first, the Cu, Zn, and Sn metal powders are wet milled at 900 rpm forming the well mixed copper binary nanocrystalline alloys, i.e., Cu/Sn (1:1) and Cu/Zn (5:8). Stoichiometric quantity of elemental sulfur S is then added, and reaction milling is continued for a specified period of time to result in one clean quaternary product that is tentatively called a pre-kesterite. It is a cubic polytype with average crystallite sizes of 8-12 nm (XRD), magnetic (EPR), shows no 65Cu and 119Sn MAS NMR spectra, and lacks semiconducting properties (UV-vis), although chemically and structurally is similar to the semiconducting tetragonal kesterite (Raman). In the second step, the pre-kesterite is thermally annealed, preferably, at 500ºC, 6 h, under argon to afford the target semiconducting kesterite nanopowders (Eg=1.35-1.40 eV). There are some advantages of such a two-step milling process, i.e., metals first to form the copper alloys followed by sulfur addition and sulfurization reactions, compared with a high energy ball milling of all four elements at once.

Biography :

Jerzy F Janik has completed his graduation in 1987 from the University of New Mexico (UNM), Albuquerque, NM (PhD in Chemistry). He has spent several years as Visiting Professor at UNM (1990-1992, 2000-2002) and at Duke University, Durham, NC (1995-1998). Currently, he is a Full Professor of Technical Sciences at the AGH University of Science and Technology, Faculty of Energy and Fuels, Kraków, Poland.
Email:janikj@agh.edu.pl