Water Additive Enhanced Solution Processing of Alloy Sb2(S1-xSex)3-Based Solar Cells

Solution process is a convenient and cost-effective approach to the deposition of thin films for optoelectronic devices. The quality of as-prepared films depends critically on the applied precursor materials as well as solvents. Herein, a method is developed to synthesize Sb-2(S1-xSex)(3) thin films and demonstrate the role played by water during the film formation. In the synthesis, antimony trichloride, selenourea, and thiourea used as Sb, Se, and S sources are dissolved in N,N-dimethylformamide and dimethyl sulfoxide mixed solvents. It is found that a tiny amount of water (1%) in the solution enables an essential increase in grain size that in turn facilitates carrier transport and suppresses recombination. The deep-level transient spectroscopy analysis shows that water additive helps to reduce defect density and type in the as-obtained films. Finally, the improved film quality leads to a certified power conversion efficiency of 7.42%, a top efficiency in Sb-2(S,Se)(3)-based solar cells regardless of the device configurations. This study provides an effective approach to tailor the optoelectronic properties of Sb-2(S,Se)(3) and a practical strategy to improve the device efficiency.