Efficient TiO 2 Surface Treatment Using Cs 2 CO 3 for Solution-Processed Planar-Type Sb 2 S 3 Solar Cells

We report a highly effective surface treatment method for planar-type Sb S solar cells by employing a Cs CO -modified compact TiO (c-TiO ) electron transport layer. It is found that surface treatment using a Cs CO solution can shift the work function of c-TiO upward and reduce its surface roughness. As a result, compared with the power conversion efficiency of untreated solar cells, that of the treated solar cells with a glass/FTO/c-TiO (/Cs CO )/Sb S /P3HT/Au structure significantly improved from 2.83 to 3.97%. This study demonstrates that the introduction of Cs CO on a c-TiO layer is a simple and efficient way to adjust the work function of the electron transport layer and fabricate high-performance planar-type Sb S solar cells.