Transparent TiO2 and ZnO Thin Films on Glass for UV Protection of PV ModulesShow others and affiliations
2019 (English)In: Frontiers in Materials, E-ISSN 2296-8016, Vol. 6, article id 259Article in journal (Refereed) Published
Abstract [en]
Failure of PV modules frequently occurs as a result of degradation of their encapsulation material by destructive UV radiation. Both the life expectancy and efficiency of PV modules can be improved by reducing the transmittance of the destructive UV radiation through the cover glass without compromising the transmittance in the visible wavelength region. In addition, if the absorbed UV photons can be down-shifted to wavelengths that can be more efficiently converted to electrical energy, an additional increase of the PV efficiency could be achieved. In this study we have investigated transparent ZnO and TiO2 thin films deposited by spray pyrolysis on soda lime silicate float glass as functional layers on PV cover glass. The optical bandgap, UV-cutoff, UV-Vis transmittance, reflectivity (total and diffuse) and photoluminescence have been determined. The ZnO coating shifted the optical bandgap to longer wavelengths, resulting in a reduction of the transmittance of destructive UV radiation by up to ~85%. Distinct photoluminescence peaks at 377 nm and at 640 nm were observed for one of the ZnO samples. The TiO2 coated glasses also showed an increased UV cutoff, which resulted in a reduction of transmittance of destructive UV radiation by up to 75%. However, no photoluminescence peaks could be observed from the TiO2 films with 325 nm excitation laser, which can be explained by the fact that only indirect interband transitions are accessible at this excitation wavelength. Deposition of both ZnO and TiO2 coatings resulted in a reduction of the transmitted light convertible by PV modules, by up to 12.3 and 21.8%, respectively. The implication of the results is discussed in terms of lifetime expectancy and efficiency of PV modules.
Place, publisher, year, edition, pages
2019. Vol. 6, article id 259
Keywords [en]
float glass, thin films, UV protection, photovoltaics modules, cover glass, transparent intelligence, solar energy materials, photoluminescence
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:ri:diva-40567DOI: 10.3389/fmats.2019.00259Scopus ID: 2-s2.0-85074668486OAI: oai:DiVA.org:ri-40567DiVA, id: diva2:1362195
2019-10-182019-10-182023-03-14Bibliographically approved