Abstract
Band-gap alignment engineering has now been extensively studied due to its high potential for application. Here we demonstrate a simple route to synthesize two metal oxide layers and align them together according to their bandgaps on the surface of crystalline silicon (c-Si) solar cells. The metal oxide layers not only extend absorption spectrum to generate extra carriers but also more efficiently separate electron⁻hole pairs. As a consequence, the photovoltaic performance of SnO₂/CdO/Si double-layer solar cell (DLSC) is highly improved compared to the controlled Si solar cell, CdO/Si and SnO₂/Si single-layer solar cells (SLSCs). Via alignment engineering, the SnO₂/CdO/Si DLSC produces a short circuit photocurrent (J(sc)) of 38.20 mA/cm², an open circuit photovoltage (V(oc)) of 0.575 V and a fill factor (FF) of 68.7%, a conversion efficiency (η) of 15.09% under AM1.5 illumination.