Manipulating Back Contact Enables Over 8%-Efficient Carbon-Based Sb2(S,Se)3 Solar Cells

The low-cost and stable carbon is known as a potential electrode candidate for high-performance Sb 2 (S,Se) 3 solar cells. However, the poor contact and absence of electron barrier at the back contact interface between Sb 2 (S,Se) 3 absorber and carbon electrode caused serious recombination and unsatisfactory performance of carbon-based Sb 2 (S,Se) 3 solar cell. In this work, an ultra-thin PbS layer with various strategies was introduced to modify the back interface. Compared with the generic PbS nanoparticles-based routes, the hydrothermal-derived PbS layer is more uniformly and closely coated on the rear surface of Sb 2 (S,Se) 3 by enjoying a unique in-situ anchoring process. As a result, a benign back contact with a well-matched interface effectively reduces the contact resistance and promotes the hole collection efficiency. Consequentially, the fill factor (FF) of the device boosts from 33.0% (control device) to 65.06% (with hydrothermal-based PbS) and also delivers a device efficiency enhancement from 3.1% to 8.0%, which is the highest FF and efficiency for the carbon-based Sb 2 (S,Se) 3 solar cells so far. This work paves a potential route for high-performance carbon-based Sb 2 (S,Se) 3 solar cells