Investigation of barium titanate thin films as simple antireflection coatings for solar cells

Barium titanate (BaTiO3, BTO) is a perovskite class material of remarkable dielectric, ferroelectric and ferro-magnetic properties. Our previous studies on optical properties of BTO thin films proved high visible transmittance and sharp absorption edge at similar to 300 nm. Therefore the usage of BTO as a UV blocker or an antireflection (AR) coating in visible region is straightforward. AR coatings are agreed to be important parts of many photonic devices, among them also of solar cells. In this paper, single layers of amorphous BTO are numerically and experimentally investigated as promising AR coatings for achieving increased light trapping in thin film silicon solar cells. Reduced reflections achieved by BTO thin films deposited using RF magnetron sputtering on a-Si:H/SiO2 compared with pristine a-Si: H/SiO2 system are clearly demonstrated. Antireflection effects are analyzed using simple AR systems comprising BTO.