Greatly Enhanced Photovoltaic Performance of Crystalline Silicon Solar Cells Using Metal Oxide Layers by Band-Gap Alignment Engineering

Band-gap alignment engineering has now been extensively studied due to its high potential application. Here we demonstrate a simple route to synthesize two metal oxide layers and align them together according to their bandgaps on surface of crystalline silicon (c-Si) solar cells. The metal oxide layers can not only extend absorption spectrum to generate extra carriers but also serve to separate electron-hole pairs more efficiently. As a consequence, the photovoltaic performance of SnO2/CdO /Si double-layer solar cell (DLSC) is highly improved compared to CdO/Si and SnO2/Si single-layer solar cells(SLSCs) and SnO2/CdO/Si double-layer solar cell (DLSC). By the alignment engineering, the SnO2/CdO/Si DLSC produces a short circuit photocurrent (Jsc) of 38.20 mA/cm2, an open circuit photovoltage (Voc) of 0.575 V and a fill factor (FF) of 68.7%, corresponding to a light to electric power conversion efficiency (η) of 15.09% under AM1.5 illumination. These results suggest that with the use of metal oxide layers by band-gap alignment engineering, new avenues have been opened for developing high-efficiency and cost-effective c-Si solar cells.