Inverted superstrate antimony selenide solar cells

Chen Qian, Kaiwen Sun, Martin Green, Xiaojing Hao University of New South Wales, Sydeny, --, Australia

Antimony selenide (Sb2Se3) solar cells have recently garnered significant attention due to their excellent stability, non-toxic nature, and abundance in Earth's resources. The superstrate configuration, chosen primarily for its low-temperature and one-step fabrication method, has become prevalent. However, the n-i-p structure dominates superstrate Sb2Se3 solar cells, limiting the flexibility when applied in tandem solar cells. To address this limitation, there is a need for a suitable p-type material that can serve as a substrate for growing this quasi-one-dimensional (Q-1D) absorber material, thus expanding its applicability in tandem solar cells. Hence, we introduce an inverted superstrate solar cell architecture where Sb2Se3 is deposited on a p-type material, MnS. We thoroughly investigate the quality of the Sb2Se3 absorber layer under different substrate temperatures. With a moderate substrate heating temperature, the Sb2Se3 thin film demonstrates improved crystallinity and enhanced favorable (hk1) ribbon orientations, resulting in the formation of an exceptional heterojunction. Our inverted superstrate Sb2Se3 solar cell exhibits a superior power conversion efficiency of 4.2%. This inverted structure broadens the application of antimony chalcogenide solar cells in tandem configurations by providing an alternative carrier transport direction. Moreover, the three-step successive thermal evaporation process employed for this inverted Cd-free device holds promise for large-scale manufacturing. The reduced concerns about toxicity and a significant cost reduction achieved by using an Al electrode instead of an Au electrode in the normal superstrate configuration further enhance the viability of this manufacturing approach in the future.