Formation of copper zinc tin sulfide thin films from colloidal nanocrystal dispersions via aerosol-jet printing and compaction

Bryce A. Williams, Ankit Mahajan, Michelle A. Smeaton, Collin S. Holgate, Eray S. Aydil, Lorraine F. Francis

Research output: Contribution to journalArticle

Abstract

A three-step method to create dense polycrystalline semiconductor thin films from nanocrystal liquid dispersions is described. First, suitable substrates are coated with nanocrystals using aerosol-jet printing. Second, the porous nanocrystal coatings are compacted using a weighted roller or a hydraulic press to increase the coating density. Finally, the resulting coating is annealed for grain growth. The approach is demonstrated for making polycrystalline films of copper zinc tin sulfide (CZTS), a new solar absorber composed of earth-abundant elements. The range of coating morphologies accessible through aerosol-jet printing is examined and their formation mechanisms are revealed. Crack-free albeit porous films are obtained if most of the solvent in the aerosolized dispersion droplets containing the nanocrystals evaporates before they impinge on the substrate. In this case, nanocrystals agglomerate in flight and arrive at the substrate as solid spherical agglomerates. These porous coatings are mechanically compacted, and the density of the coating increases with compaction pressure. Dense coatings annealed in sulfur produce large-grain (>1 μm) polycrystalline CZTS films with microstructure suitable for thin-film solar cells.

Original languageEnglish (US)
Pages (from-to)11526-11535
Number of pages10
JournalACS Applied Materials and Interfaces
Volume7
Issue number21
DOIs
StatePublished - Jun 3 2015

Keywords

  • aerosol-jet printing
  • copper zinc tin sulfide
  • nanocrystal
  • nanoparticle coating
  • spray coating
  • thin-film solar cell

ASJC Scopus subject areas

  • Materials Science(all)

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