Grain Engineering of Sb S Thin Films to Enable Efficient Planar Solar Cells with High Open-Circuit Voltage.

Sb S is a promising environmentally friendly semiconductor for high performance solar cells. But, like many other polycrystalline materials, Sb S is limited by nonradiative recombination and carrier scattering by grain boundaries (GBs). This work shows how the GB density in Sb S films can be significantly reduced from 1068 ± 40 to 327 ± 23 nm µm by incorporating an appropriate amount of Ce into the precursor solution for Sb S deposition. Through extensive characterization of structural, morphological, and optoelectronic properties, complemented with computations, it is revealed that a critical factor is the formation of an ultrathin Ce S layer at the CdS/Sb S interface, which can reduce the interfacial energy and increase the adhesion work between Sb S and the substrate to encourage heterogeneous nucleation of Sb S , as well as promote lateral grain growth. Through reductions in nonradiative recombination at GBs and/or the CdS/Sb S heterointerface, as well as improved charge-carrier transport properties at the heterojunction, this work achieves high performance Sb S solar cells with a power conversion efficiency reaching 7.66%. An impressive open-circuit voltage (V ) of 796 mV is achieved, which is the highest reported thus far for Sb S solar cells. This work provides a strategy to simultaneously regulate the nucleation and growth of Sb S absorber films for enhanced device performance.