Annealing materials and methods for annealing photovoltaic devices with annealing materials

A method for treatment of an absorber layer on a layer stack for a photovoltaic device, comprising:

• preparing an annealing material comprising cadmium chloride and a thickening agent,
• wherein:
• a ratio of the cadmium chloride to the thickening agent in the annealing material is in a range from 1:1 to 160:1, by weight;
• the thickening agent comprises at least one of Methyl Cellulose, HydroxyPropyl Methyl Cellulose, or Propylene Glycol;
• and
• the annealing material has a viscosity in a range of 5 to 250 millipascal seconds;
• applying a substantially uniform coating of the annealing material to a surface of the absorber layer, wherein the absorber layer comprises cadmium and tellurium, and the absorber layer is doped with a group V dopant;
• forming a film having area density in a range of 0.15 mg/cm2 to 1.20 mg/cm2 by drying the annealing material applied to the absorber layer;
• and
• processing the absorber layer with the film in contact with the surface of the absorber layer, at an annealing temperature in a range of 350° C. to 650° C. for between 5 minutes and 60 minutes.