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 the 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 textured Si substrates was found to be 100% (at 550 nm) and 85% (at 400 nm), respectively. Further, improvement in cell efficiency of a Si solar cell with a-BTO anti-reflection coating was found with an increase from 9.3% to 10% accompanied by improvements in overall performance parameters such as short circuit density (J_sc), open circuit voltage (V_oc) and fill factor (FF). These results indicate that an a-BTO thin film deposited using RF magnetron sputtering can be used as an alternative anti-reflection coating for Si based photovoltaic cells.