Method for preparing a compound-based film for use in a solar cell by photo-electrodeposition

A method for preparing a film of a CIS semiconductor compound overcoated by a color layer by photo-electrodeposition, comprising:

• (a) preparing an electrolyte solution by mixing precursors of film constituents including Cu, In, and Se with a solvent;
• (b) configuring an electrodeposition circuit by connecting an electrochemical cell comprising the electrolyte solution, a working electrode, and a counter electrode to a voltage or current supply device;
• (c) disposing a photomask having a predetermined pattern on the working electrode;
• (d) producing the film through the photomask in the predetermined pattern on a surface of the working electrode according to a difference in thickness of the film between a region where light arrives and a region where light does not arrive, by:
• (i) applying a reduction voltage or current to the working electrode on which the photomask is disposed;
• (ii) disposing a light source to emit light toward the photomask;
• and
• (iii) photoelectrically depositing the film of the CIS semiconductor compound on the surface of the working electrode at least in the predetermined pattern by reducing the precursors while illuminating the light source through the photomask;
• (e) subjecting the film to heat treatment under a gas atmosphere comprised of sulfur or selenium;
• and
• (f) forming the color layer consisting essentially of CuSe at least in the predetermined pattern on the film of the CIS semiconductor compound, after heat treatment, with the film employed as a working electrode using photo-electrodeposition.