Copper-Zinc-Tin-Sulfide Thin Films via Annealing of Ultrasonic Spray Deposited Nanocrystal Coatings

Bryce A. Williams, Nancy D. Trejo, Albert Wu, Collin S. Holgate, Lorraine F. Francis, Eray S. Aydil

Research output: Contribution to journalArticle

Abstract

Thin polycrystalline films of the solar absorber copper-zinc-tin-sulfide (CZTS) were formed by annealing coatings deposited on molybdenum-coated soda lime glass via ultrasonic spraying of aerosol droplets from colloidal CZTS nanocrystal dispersions. Production of uniform continuous nanocrystal coatings with ultrasonic spraying requires that the evaporation time is longer than the aerosol flight time from the spray nozzle to the substrate such that the aerosol droplets still have low enough viscosity to smooth the impact craters that form on the coating surface. In this work, evaporation was slowed by adding a high boiling point cosolvent, cyclohexanone, to toluene as the dispersing liquid. We analyzed, quantitatively, the effects of the solvent composition on the aerosol and coating drying dynamics using an aerosol evaporation model. Annealing coatings in sulfur vapor converts them into polycrystalline films with micrometer size grains, but the grains form continuous films only when Na is present during annealing to enhance grain growth. Continuous films are easier to form when the average nanocrystal size is 15 nm: using larger nanocrystals (e.g., 20 nm) sacrifices film continuity.

Original languageEnglish (US)
Pages (from-to)18865-18871
Number of pages7
JournalACS Applied Materials and Interfaces
Volume9
Issue number22
DOIs
StatePublished - Jun 7 2017

Keywords

  • copper-zinc-tin-sulfide
  • grain growth
  • nanocrystal
  • thin-film solar cell
  • ultrasonic spray coating

ASJC Scopus subject areas

  • Materials Science(all)

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