One-Step Electrodeposition of CZTS for Solar Cell Absorber Layer

Abstract

CZTS thin films were obtained by one-step electrochemical deposition from aqueoussolution at room temperature. Films were deposited on two different substrates, ITOon PET, and electropolished Mo. Differently from previous studies focusing exclu‐sively on the formation of kesterite (Cu4ZnSnS4), here, the synthesis of a phase withthis exact composition was not considered as the unique objective. Really, startingfrom different baths, amorphous semiconducting layers containing copper–zinc–tin–sulphur with atomic fraction Cu0.592Zn0.124Sn0.063S0.221 and Cu0.415Zn0.061Sn0.349S0.175, werepotentiostatically deposited. Due to the amorphous nature, it was not possible to de‐tect if one or more phases were formed. By photoelectrochemical measurements, weevaluated optical gap values between 1.5 eV, similar to that assigned to kesterite, and1.0 eV. Reproducibility and adhesion to the substrate were solved by changing S withSe. Preliminary results showed that an amorphous p-type layer, having atomic frac‐tion Cu0.434Zn0.036Sn0.138Se0.392and an optical gap of 1.33 eV, can be obtained by one-stepelectrochemical deposition.