SnS and SnS2 films by direct-coating from same molecular ink

Abstract

SnS and SnS2 thin films have been direct-coated on glass from similar inks prepared by dissolving 1:1 M ratio of SnCl2 and thiourea (TU) in methanol (MEI) or ethylene glycol (EGI). Films were deposited on glass by drop-casting, drying and finally heating in air from 200 to 360 °C. EGI-precursor films heated from 300 to 340 °C yielded mixture of SnS2 and SnS while only SnS films were obtained above 360 °C. However, MEI produced SnS2 films above 200 °C. SnS and SnS2 films have band gaps of 1.45 and 2.4 eV, respectively. The SnS films were n-type with conductivity, mobility and electron concentration of 1–2 S/cm, 2 cm2/V.s and 1018 cm−3, respectively. The SnS2 films were also n-type with conductivity, mobility and electron concentration of ~10−5 S/cm, 0.6 cm2/V.s and ~1014 cm−3, respectively. Formation of SnSx films were explained on the basis of thermolysis of Sn+2-TU complex in air.