Cu2ZnSnS4 (CZTS) nanoparticles were prepared by micro wave assisted synthesis. 1:1 ratio of trioctylphosphine oxide and oleylamine used as a mixed solvent. Co-solvent effect shows improvement in the CZTS NPs (nanoparticles) formation. NPs with Cu1.8Zn1.4SnS3.6 composition and 1.5 eV band gap have been obtained. CZTSSe absorber has a bi-layer structure and solar cell shows 4.48% efficiency.