Effects of Grain Size on the UV‐Photoresponse of Zinc Oxide Thin Films Grown by Spray‐Pyrolysis

Abstract

Zinc oxide films with different average grain size are deposited on glass substrates by spray‐pyrolysis at 425 °C. Samples are characterized by XRD, UV–Vis transmittance, FE‐SEM, and electrical properties measurements. The increase in conductivity observed under 365 nm wavelength illumination is evaluated in terms of grain size. Films with small grains (120 nm) show higher response with respect to films with larger grains (230 and 300 nm). A model considering resistivity and grain size for the prediction of the response of films in terms of UV‐to‐dark conductivity ratio is proposed and validated with experimental results.

Transparent TiO2 and ZnO Thin Films on Glass for UV Protection of PV Modules

“…The amount of precursor solution sprayed onto every glass sample is shown in Table 2, and the denotation of each sample according to the numbering. We believe that the deposited coatings are thin (<100 nm), mostly amorphous for both ZnO (Kamata et al, 1994;Hosseinmardi et al, 2012;Villegas et al, 2018) and TiO 2 (Okuya et al, 1999;Abou-Helal and Seeber, 2002). This will be discussed in section Change in Transmittance and Reflection and section Effect on Photoluminescence.…”

“…The photoluminescent bands that we interpret as defects and the Fe 3+ sensitization emissions for the samples are strong and dominate the photoluminescence spectra, see Figure 7. For the ZnO-coated samples it is despite that similar literature data, but with somewhat different experimental circumstances, refer to the ZnO films as mostly crystalline (Kamata et al, 1994;Hosseinmardi et al, 2012;Villegas et al, 2018).…”