Direct-coated copper nickel tin sulphide (Cu2NiSnS4) thin films from molecular ink

This paper describes direct-coating of earth-abundant Cu2NiSnS4 (CNTS) thin films on glass from molecular ink synthesized easily by dissolving metal salts and thiourea in methanol. Films were prepared by dip-coating and drop-casting of precursor films and subsequent annealing at 160 °C in air. X-ray Diffraction (XRD) of films confirmed cubic CNTS. Scanning Electron Microscope (SEM) revealed that dip-coated films are continuous whereas drop-casted ones are granular with voids between the grains. The band gap of CNTS is about 1.6 eV with electrical conductivity of 1.7 × 10−3 S/cm and hole mobility of 2.3 × 10−3 cm2/Vs.