A liquid medium annealing strategy for highly [041]/[141]-oriented planar antimony sulfide solar cells with 7.23% efficiency

Antimony sulfide (Sb2S3) is regarded as one of candidate materials for tandem top cells with silicon based solar cells due to its non-toxicity, appropriate bandgap, high absorption coefficient and good stability. However, restricted by the difficulty of carrier transportation caused by unfavorable orientations of Sb2S3, the power conversion efficiency (PCE) is still relatively low. In this work, a new annealing method, called liquid medium annealing (LMA), is developed to versatilely regulate the orientation of Sb2S3 films by controlling the concentration of Se22--OAm. Compared with conventional vapor-assisted annealing, a highly [041]/[141] oriented Sb2S3 film with unique title angles can be skillfully prepared by LMA with top-down model, which facilitates the photo-induced carrier separation along (Sb4S6)n ribbon. Meanwhile, such a LMA tactic can effectively tailor the band alignment at back contact by raises the valence band maximum (VBM) of Sb2S3, and then reducing hole collection barrier. Finally, a high PCE of 7.23% is achieved and considered the first echelon in planar Sb2S3 solar cells.