Inkjet printing of metal oxide coatings for enhanced photovoltaic soiling environmental applications

Global energy needs have gradually shifted toward photovoltaic solar energy, especially in the Gulf region because of the high solar-irradiance potential. However, one of the main challenges for this technology in the region is soiling, which has been reported to degrade the power output of photovoltaic modules significantly. Anti-soiling coatings are promising technologies to minimize the effect of dust on photovoltaic solar panels. Accordingly, this study aimed to synthesize aluminum, zinc, titanium, and tin oxides using mixed-based and nanoparticle-based precursors through inkjet printing techniques and investigate their potential in anti-soiling applications for PV panels. Four metal oxides, namely, aluminum, zinc, titanium, and tin oxides, were synthesized and deposited using the inkjet printing technique for anti-soiling application. Ultraviolet-visible spectroscopy, field emission scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and contact angle measurements were performed to characterize these thin films. The optical transmittance of the substrate using the nanoparticle ink revealed better optical properties than that using the mixed-based ink. Compared with nanoparticle samples, a homogeneous crack and a defect-free layer were observed with dense nanoparticles in all mixed inks (except for aluminum oxide ink). The contact angles indicated that the synthesized films were super-hydrophilic/hydrophilic coatings. The results of the outdoor testing revealed that up to 60% less dust was deposited on the best-performing film (aluminum oxide mixed-based ink) compared with bare glass.  The outdoor experiment revealed that mixed-based thin films were better in reducing dust deposition than nanoparticle-based thin films and bare glass. This enhancement might be due to the decreased antireflection property along with a morphological contribution related to the presence of nanoparticle voids, which reduce the spectra scattering and minimize its deterioration, thus demonstrating better anti-soiling properties. The results of the outdoor test revealed that aluminum, zinc, and titanium oxides are promising materials for anti-soiling coating applications for both ink types. However, tin oxide coatings are not recommended for anti-soiling applications, as they showed the highest dust deposition rate near the bare glass performance.