An amorphous barium titanate thin film improves light trapping in Si solar cells

Abstract

A new anti-reflection coating based on amorphous barium titanate (a-BTO) was developed using RF magnetron sputtering technique. Systematic studies on the structural and optical properties were carried on a-BTO thin films deposited on polished Si and textured Si substrates. In the visible range of solar spectrum, the refractive index was found to be 2.02-1.91 with high transmittance of greater than 85 %. Maximum reduction in the reflectance for a-BTO on polished Si and texture Si substrates was found to be 100 % (at 550 nm) to 85 % (at 400 nm), respectively. Further, improvement in cell efficiency of Si solar cell with a-BTO anti-reflection coating was found to increase from 9.3 % to 10 % with improvement in overall performance parameters such as short circuit density (J sc ), open circuit voltage (V oc ) and fill factor (FF).These results indicates that a-BTO thin film deposited using RF magnetron sputtering can be used as alternative anti-reflection coatings for Si based photovoltaic cells.

Control of Oxygen Vacancies in TiO6 Octahedra of Amorphous BaTiO3 Thin Films with Tunable Built‐In Electric Field in a‐BaTiO3/p‐Si Heterojunction for Metal–Oxide–Semiconductor Applications

“…Among the contenders, perovskite BaTiO 3 (BTO), as a typical lead‐free displacement‐type ferroelectric featuring a large dielectric constant, stands out . Many researchers have investigated the functionalities of BTO thin film deposited on Si substrates, which not only can be used as a gate insulator, but also has other properties such as a rectifying effect, a photovoltaic effect, a room temperature luminescent effect, and an antireflection effect …”

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

“…for antireflection. Perovskite titanium oxides have already been reported to operate as effective AR single layer coatings for silicon solar cells [6].…”

“…BTO thin films are distinguished by broad UV Vis transparency and relatively high refractive index > 2.0 (589 nm) [6,24,25]. Therefore similarly to well-known high-refractive index oxides, e.g.…”

“…Therefore concepts of trapping light in solar cell absorbers using BTO AR coatings could be promising. Improved light-trapping in solar cells using a single layer [6] or multilayer ferroelectrics have already been reported [26,27]. Benefits of using ferroelectric materials as AR coatings come from their relatively simple technological preparation and the sensitivity of their physical properties to external effects, e.g.…”

Design of multi-layer anti-reflection coating for terrestrial solar panel glass

“…Alternatively, porous SiO 2 is preferred due to reasonably low refractive index (n < 1.45) with good environmental stability and durability. Recently, authors have demonstrated improvement in light trapping in Si solar cells with maximum reduction in reflection by 85-100% in visible region of 400-550 nm when amorphous BaTiO 3 thin film with refractive index of 2.02-1.91 were deposited over Si solar cells [4]. However, single layer anti-reflection coating can minimize reflections at one specific wavelength typically at normal incidence which limits its use for broad visible range.…”