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

The Sb 2 S 3 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 Sb 2 S 3 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 Sb 2 S 3 absorber films via pH regulation and nominal cation doping. The careful characterization of Sb 2 S 3 films reveals that the manipulation of the chemical environment of CBD precursor solutions promotes the heterogeneous nucleation and growth of Sb 2 S 3 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 Sb 2 S 3 films. Benefitting from the suppressed nonradiative recombination and increased carrier concentration, the resultant planar Sb 2 S 3 solar cells yield a competitive power conversion efficiency of 7.90%. Furthermore, a high‐performance Sb 2 S 3 solar minimodule with an active area of 16.25 cm 2 is first constructed using laser scribing. This work underscores the importance of the precursor engineering for solution‐processed antimony chalcogenide solar cells.