Solution-processed SnO2 interfacial layer for highly efficient Sb2Se3 thin film solar cells

Antimony selenide (Sb2Se3) thin film solar cells have gained worldwide intense research owing to their suitable bandgap, high absorption coefficient, benign grain boundaries, earth-abundant element constituents and low fabrication cost. It is extremely important to investigate the interface passivation and minimize the carrier recombination to realize high-efficiency Sb2Se3 solar cells. Very little is known, however, about the carrier recombination mechanisms at the interfaces of Sb2Se3 solar cells. Herein, we show that a novel solution-processed SnO2 layer (∼12 nm) incorporated into Sb2Se3 thin film solar cells results in high power conversion efficiency of 7.5%, namely, an improvement of 39% relative to that of the solar cell without SnO2 interfacial layer. Furthermore, the open-circuit voltage (Voc) is the highest ever reported for Sb2Se3 solar cells. These improvements benefit from the better preferred [221] orientation, less bulk and interfacial defects in the Sb2Se3 absorbers, and relatively ideal heterointerfaces due to the SnO2 passivation. This work opens up new routes for the critical importance of interfacial control in Sb2Se3 solar cells, which could be extended to other emerging low-dimensional thin film solar cells.