Spray deposited TiO2 thin films for large-area TiO2/p-Si heterojunction solar cells

Carrier selective contacts (CSC) have the potential to lower the cost of photovoltaic (PV) cells. In the present work p-Si/TiO2 heterojunction solar cells have been fabricated using titanium dioxide (TiO2) as an electron-selective layer. Thin uniform anatase TiO2 films have been deposited using a commercially viable spray deposition technique over large area Si substrates. With a simple architecture of Al (200 nm fingers)/Al (15 nm thin film)/TiO2/c-Si(p)/Ag (200 nm), a highest conversion efficiency of 1.56 % has been achieved for the TiO2 carrier selective contact based solar cell with an active area of ~3.84 cm2. The minority carrier lifetime value of the TiO2 coated Si wafer was found to be less than that of the uncoated wafer, indicating the inability of the anatase TiO2 layer to provide surface passivation. Suns-VOC measurements yielded comparable values of the implied open circuit voltage for both the uncoated and the TiO2 coated Si wafers. Spray deposition technique can be used for scalable fabrication of carrier selective contact based heterojunction solar cells.