Paper EM-MoA4
Aerosol Spray Pyrolysis Synthesis and Characterization of CZTS Nanoparticles

Monday, November 10, 2014, 3:00 pm, Room 314

A novel synthesis technique for the production of copper zinc tin sulfide (CZTS) nanocrystals has been developed using aerosol spray pyrolysis. CZTS is a quaternary semiconducting material that shows promise as a replacement to common semiconductors such as CdTe and CIGS for use in photovoltaic devices. CIGS is currently being commercialized in the photovoltaic industry, but rare and expensive indium and gallium components threaten its long term viability. CZTS looks to be one of the best alternatives to CIGS with all earth abundant and non-toxic materials and a band gap of 1.5 eV [1]. A number of synthesis techniques have been thoroughly studied and detailed previously. In our novel approach, we synthesize single-phase 15 nm nanocrystals starting with zinc, copper, and tin diethyldithiocarbamate precursors in a toluene solvent. The precursor solution is aerosolized using a Collison type nebulizer wherein the droplets are pushed through a tube furnace and nucleation occurs at atmospheric pressure. The powder is then collected in a series of methanol-filled bubblers. We reproducibly synthesize kesterite, Cu₂ZnSnS₄, nanocrystals. This technique continuously converts the chemical precursor into high-purity nano powder with a production rate of ~50mg/hour from ~100mL of precursor solution with ~500mg total of the three diethyldithiocarbamate precursors for an un-optimized lab-scale reactor. The motivation to use this synthesis process as an inexpensive, quick, and simple method of nanocrystal formation will be outlined. Further, a discussion of process parameters on the stoichiometry of the nanoparticles will be presented as well as results from extensive material characterization via Raman spectroscopy, EDS, XRD, and TEM. We are currently in the process of producing a printable ink technique with which to coat CZTS as the absorbing layer for use in photovoltaic devices.

[1] H. Wang. “Progress in Thin Film Solar Cells Based on Cu₂ZnSnS₄,” International Journal of Photoenergy, 2011.