One-Step Electrodeposition of CZTS for Solar Cell Absorber Layer

Abstract

CZTS thin films were obtained by one-step electrochemical deposition from aqueous solution at room temperature. Films were deposited on two different substrates, ITO on PET, and electropolished Mo. Differently from previous studies focusing exclu‐ sively on the formation of kesterite (Cu 4 ZnSnS 4), here, the synthesis of a phase with this exact composition was not considered as the unique objective. Really, starting from different baths, amorphous semiconducting layers containing copper–zinc–tin– sulphur with atomic fraction Cu 0.592 Zn 0.124 Sn 0.063 S 0.221 and Cu 0.415 Zn 0.061 Sn 0.349 S 0.175 , were potentiostatically deposited. Due to the amorphous nature, it was not possible to de‐ tect if one or more phases were formed. By photoelectrochemical measurements, we evaluated optical gap values between 1.5 eV, similar to that assigned to kesterite, and 1.0 eV. Reproducibility and adhesion to the substrate were solved by changing S with Se. Preliminary results showed that an amorphous p-type layer, having atomic frac‐ tion Cu 0.434 Zn 0.036 Sn 0.138 Se 0.392 and an optical gap of 1.33 eV, can be obtained by one-step electrochemical deposition.