An In Situ Polymerization-Assisted Grain Growth Strategy for Efficient and Stable Sb₂S₃ Solar Cells

Antimony sulfide (Sb 2 S 3 ) stands out as an exemplary material for the light-absorbing layer in solar cells, attributed to its favorable light absorption properties, eco-friendliness, and robust stability. However, undesirable [ hk 0] crystal orientation and the presence of pinholes will degrade film quality and device performance. Here, an in situ polymerization-assisted grain growth strategy was introduced by adding monomer acrylic acid (AA) to the growth solution during the chemical bath deposition (CBD) process of Sb 2 S 3 . At the initial stage, AA serves as a complexing agent, coordinating with Sb 3+ ions to mitigate particle agglomeration in the solution, which not only enhances the film quality but also ensures a more desirable [ hk 1] crystal orientation. During the reaction, in situ synthesized poly(acrylic acid) (PAA) builds coordination bonds with Sb 3+ through the carboxyl groups, inducing the cross-linking of Sb 2 S 3 grains. This cross-linking yields compressive constraints and reduces the number of pinholes in the Sb 2 S 3 films, culminating in improved film quality and reinforced device steadiness. Consequently, the best power conversion efficiency (PCE) of the AA-modified Sb 2 S 3 solar cell reached 7.12% (compared to 6.70% for the control), Furthermore, incorporating an additional SnO 2 electron transport layer and a BTR-TPA interfacial layer bolstered the efficiency to 7.51%.