The growth of Cu2 − xSe thin films using nanoparticles

► Cu2 − xSe thin films was formed for the CuIn1 − xGaxSe2 absorber fabrication. ► Non-vacuum process is low cost and easy method comparing to vacuum process. ► Cu2 − xSe nanoparticles were synthesized by a low temperature colloidal process. ► Coated Cu2 − xSe nanoparticles were selenized with several different conditions. ► The control of phase evolution is a key factor in forming dense Cu2 − xSe thin films.