The structural, optical, and self-cleaning properties of Mn3O4/SnO2 multilayer thin films deposited using spray pyrolysis technique

Due to the wide applications of self-cleaning surfaces in various industries such as textile, automotive, construction, agriculture, optics, marine and aerospace industries, the development of self-cleaning coating production methods in a simple and inexpensive way has been considered by researchers. In this paper, Tin oxide (SnO2) and Manganese (II, III) oxide (Mn3O4) were prepared via sol–gel procedure. Next, (Mn3O4/ SnO2) double-layers were deposited using spray pyrolysis system on glass substrates. According to AFM images of Mn3O4 thin films, grains are tightly packed, entirely compressed and without crack. AFM images of SnO2 films indicated that the width of grain was about 242.8 nm and RMS roughness was about 25.85 mm. These images for bilayer demonstrated that the grain width was about 130-220 nm and root-mean-square thickness was about 20 mm. The SnO2 and Mn3O4 films, and SnO2/Mn3O4 bilayer showed a direct optical band gap and hydrophilicity with water contact angle of 75◦, 31◦, and 70◦ respectively. Due to the importance and various applications of hydrophilic surfaces, in this research, thin layers of metal oxide were produced in a very simple way, among which the thin layer of Mn3O4 has good hydrophilicity.