Sputtering of Molybdenum as a Promising Back Electrode Candidate for Superstrate Structured Sb2S3 Solar Cells

Sb2 S3 is rapidly developed as light absorber material for solar cells due to its excellent photoelectric properties. However, the use of the organic hole transport layer of Spiro-OMeTAD and gold (Au) in Sb2 S3 solar cells imposes serious problems in stability and cost. In this work, low-cost molybdenum (Mo) prepared by magnetron sputtering is demonstrated to serve as a back electrode in superstrate structured Sb2 S3 solar cells for the first time. And a multifunctional layer of Se is inserted between Sb2 S3 /Mo interface by evaporation, which plays vital roles as: i) soft loading of high-energy Mo particles with the help of cottonlike-Se layer; ii) formation of surficial Sb2 Se3 on Sb2 S3 layer, and then reducing hole transportation barrier. To further alleviate the roll-over effect, a pre-selenide Mo target and consequentially form a MoSe2 is skillfully sputtered, which is expected to manipulate the band alignment and render an enhanced holes extraction. Impressively, the device with an optimized Mo electrode achieves an efficiency of 5.1%, which is one of the highest values among non-noble metal electrode based Sb2 S3 solar cells. This work sheds light on the potential development of low-cost metal electrodes for superstrate Sb2 S3 devices by carefully designing the back contact interface.