Use of n-type amorphous silicon films as an electron transport layer in the perovskite solar cells

We have investigated the use of n-type amorphous silicon (n-a-Si) films as the electron transport layers (ETL) in perovskite (PVK) solar cells, aiming at the application to PVK/Si tandem solar cells. The use of n-a-Si as the ETL in MAPbI 3 PVK solar cells was attempted, and the power conversion efficiency (PCE) of fluorine-doped tin oxide- (FTO-) based solar cells was improved due to an improvement in coverage on FTO with thicker n-a-Si, but the external quantum efficiency in the short wavelength region was decreased due to parasitic absorption of n-a-Si. The use of indium tin oxide with a flat surface resulted in a PCE of 1.25% for the solar cells with 10 nm-thick n-a-Si. This work indicates that n-a-Si is a potential ETL candidate for PVK solar cells and provides strategic guidance for the future vacuum-integrated process of PVK/Si heterojunction tandem solar cells, which can be feasible for efficient mass production.