We report the preparation of Cu2SixSn1-xS3 thin films for thin film solar cell absorbers using the reactive magnetron co-sputtering technique.Energy dispersive spectrometer and x-ray diffraction analyses indicate that Cu2Si1-xSnxS3 thin films can be synthesized successfully by partly substituting Si atoms for Sn atoms in the Cu2SnS3 lattice,leading to a shrinkage of the lattice,and,accordingly,by 2θ shifting to larger values.The blue shift of the Raman peak further confirms the formation of Cu2SixSn1-xS3.Environmental scanning electron microscope analyses reveal a polycrystalline and homogeneous morphology with a grain size of about 200-300 nm.Optical measurements indicate an optical absorption coefficient of higher than 104 cm-1 and an optical bandgap of 1.17±0.01 eV.Solar cells based on Cu(In,Ga)Se2 (CIGS) absorbers have achieved conversion efficiencies as high as 20.3％,holding the record for thin film photovoltaics.[1] However,using the rare and expensive elements In and Ga limits the scalability to GWp/yr power production levels.Fortunately,Cu2SixSn1-xS3 (CSTS) is one of the potential earthabundant alteatives to Cu(In,Ga)Se2,and can replace In and Ga with inexpensive and benign elements due to its similar electronic and crystal structure.[2- 5]