Precursor Engineering of Chemical Bath Deposited Sb ₂ S ₃ Films for Efficient Planar Solar Cells and Minimodules

The Sb₂S₃ absorber has received tremendous attention in recent years for high-performance solar cells due to its excellent optoelectronic properties, especially for indoor photovoltaics that have gained significant interest as a sustainable solution for powering Internet of Things electronics. However, the Sb₂S₃ absorber suffers from its complicated defect characteristic, which is closely associated with the quasi-1D crystal structure. Herein, a chemical bath deposition (CBD) based precursor engineering strategy is developed to deposit high-quality Sb₂S₃ absorber films via pH regulation and nominal cation doping. The careful characterization of Sb₂S₃ films reveals that the manipulation of the chemical environment of CBD precursor solutions promotes the heterogeneous nucleation and growth of Sb₂S₃ films on the substrate, further resulting in the reduction in the grain boundary (GB) density. The reduced GB contributes to the decrease in defect density in Sb₂S₃ films. Benefitting from the suppressed nonradiative recombination and increased carrier concentration, the resultant planar Sb₂S₃ solar cells yield a competitive power conversion efficiency of 7.90%. Furthermore, a high-performance Sb₂S₃ solar minimodule with an active area of 16.25 cm² is first constructed using laser scribing. This work underscores the importance of the precursor engineering for solution-processed antimony chalcogenide solar cells.