| Cu2ZnSn(S,Se)4 (CZTSSe) is a semiconducting material with potential application as the absorber layer in thin-film photovoltaic (PV) devices. Closely related to the commercially available Cu(In,Ga)Se 2 (CIGS) absorber material, CZTSSe consists of more readily-available materials, and may therefore offer cost reduction and highly scalable production potential if its PV properties can be controlled and improved.;This work presents a two-step process for fabricating CZTSSe: the metals Cu, Zn, and Sn are electrodeposited on a suitable conducting back-contact material, and then the resulting films are reacted under hydride gases, providing selenium and/or sulfur to form the final films.;Reaction of the metal precursors in hydrogen sulfide (H2S) and/or hydrogen selenide (H2Se) yields the quaternary films Cu 2ZnSnS4 (CZTS), Cu2ZnSnSe4 (CZTSe), or CZTSSe, usually alongside a number of secondary phases. The effects of reaction conditions are examined to gain insight into the kinetic and thermodynamic properties of the reaction, which also enhances understanding of the presence of secondary phases in the reacted films.;Prior to this work, the value of Gibbs free energy of formation for CZTSe had been unreported. Herein, empirical results from simultaneous H2S/H 2Se reaction are combined with a previous estimate for the Gibbs free energy of formation of CZTS to estimate that of CZTSe. The new estimate for DeltaG-formation of CZTSe indicates that the reaction is not strongly driven toward the quaternary, a finding which is confirmed by the secondary phases remaining after the reaction has completed. |
