| AVS 62nd International Symposium & Exhibition | |
| Electronic Materials and Processing | Friday Sessions |
| Session EM+AS+EN+NS-FrM |
| Session: | Nanoparticles for Electronics and Photonics |
| Presenter: | Stephen Exarhos, University of California - Riverside |
| Authors: | S. Exarhos, University of California - Riverside A. Alvarez, University of California - Riverside J. Hernandez, University of California - Riverside L. Mangolini, University of California - Riverside |
| Correspondent: | Click to Email |
An innovative and scalable synthesis approach to the formation of stoichiometric Cu2ZnSnS4 (CZTS) nanocrystals has been developed using aerosol spray pyrolysis. This quaternary phase material is a potential replacement for currently commercialized semiconductors such as CdTe and CIGS that are used in photovoltaic devices. However, sustainability and environmental issues threaten long-term viability of these materials. Based upon earth abundant constituents and low chemical toxicity, CZTS, with a reported bandgap of ~1.5 eV[1], appears to be a superior alternative to these other materials. Additional research and development is necessary to increase the efficiency of CZTS-based cells from the current record (12.6% by Wang et al.[2]) to the >18% necessary to be considered commercially viable. Our work demonstrates the controllable, cost-effective, and reproducible synthesis of high-quality CZTS nanoparticles and films. A modified spray pyrolysis method involving decomposition of copper, zinc, and tin diethyldithiocarbamate precursors allows uniform incorporation of dopants (such as sodium) that are known to increase crystal grain growth during nanoparticle sintering[3]. Once formed, the nanoparticles are deposited onto a substrate from a methanol dispersion using an “ink-spray” process with an argon-driven airbrush. To form an efficient absorber layer in a photovoltaic device, the coating is then annealed in a sulfur-vapor atmosphere resulting in a thin film with uniformly large crystal grain morphology throughout the film thickness (~1-2 µm). The deposited films are characterized with respect to crystalline phase, stoichiometry, and overall film quality. Further preliminary results regarding the formation of Cu2ZnSn(1-x)(IV)xS4 by means of this processing approach will be reported.
[1] H. Wang. “Progress in Thin Film Solar Cells Based on Cu2ZnSnS4,” International Journal of Photoenergy 2011 (2011).
[2] Wang, Wei, Mark T. Winkler, et al. “Device Characteristics of CZTSSe Thin-Film Solar Cells with 12.6% Efficiency.” Advanced Energy Materials 4, no. 7 (2014).
[3] Johnson, M., S. V. Baryshev, et al. “Alkali-Metal-Enhanced Grain Growth in Cu2ZnSnS4 Thin Films.” Energy & Environmental Science 7, no. 6 (2014): 1931–38.