Efficiency Improvement of Sb2Se3 Solar Cells via Grain Boundary Inversion

Sb 2 Se 3 is a promising low-cost and low-toxicity photovoltaic material. Recent research revealed that recombination losses in the absorber limited the efficiency of Sb 2 Se 3 solar cells. Herein we demonstrated a strategy of grain boundary (GB) inversion to alleviate such recombination loss. Owning to its one-dimensional crystal structure, we successfully inverted the GBs of Sb 2 Se 3 films by introducing n-type Cu interstitial doping at GBs via low-temperature CuCl 2 treatment. A built-in electric field is established between p-type grain interiors and n-type GBs, which spatially separates phototogerated carriers, suppresses recombination, and enhances carrier collection. Finally, we obtained an efficiency of 7.04%, which is the highest efficiency of Sb 2 Se 3 solar cells based on rapid thermal evaporation technology. We envision that this GB inversion strategy is generally applicable to Sb 2 Se 3 solar cells with different device configuration or produced from other methods and is extendable to other emerging low-dimensional solar cells.