Fabrication of highly crystallized Cu2SnS3 thin films through sulfurization of Sn-rich metallic precursors

• Cu2SnS3 films are obtained through sulfurization of Sn-rich metallic precursors.
• The films show compact surface consisting columnar grains of several micrometers.
• Sn-rich precursors self-adjust to stoichiometric Cu2SnS3 films after sulfurization.
• Formation of pores and impurity phases are inhibited by optimizing Cu/Sn ratio.

Cu2SnS3 is an emerging material with great potential for applications in thin film solar cells. However, the conversion efficiency of Cu2SnS3-based solar cells is mainly limited by the poor crystallization and microstructure of the absorber layer. Here we report a fabrication route that can form compact, single-phase Cu2SnS3 films through sulfurization of Sn-rich metallic precursors. In the high quality films, deposited both on bare soda lime glass substrates and on Mo-coated glass substrates, columnar grains with width and length of several micrometers extend through the thickness of the films. After sulfurization, the composition of sulfide films obtained from Sn-rich precursors self-adjusts to the stoichiometry of Cu2SnS3. Furthermore, the impurity phases and pores in films can be inhibited efficiently by using precursors with Cu/Sn ratio close to 2. The band gap energy value of the fabricated Cu2SnS3 thin film is determined to be 1.35 eV, suggesting the application potential of this thin film in solar cells.

Figure optionsDownload as PowerPoint slide