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

Antimony sulfide (Sb2S3) 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 [hk0] 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 Sb2S3. At the initial stage, AA serves as a complexing agent, coordinating with Sb3+ ions to mitigate particle agglomeration in the solution, which not only enhances the film quality but also ensures a more desirable [hk1] crystal orientation. During the reaction, in situ synthesized poly(acrylic acid) (PAA) builds coordination bonds with Sb3+ through the carboxyl groups, inducing the cross-linking of Sb2S3 grains. This cross-linking yields compressive constraints and reduces the number of pinholes in the Sb2S3 films, culminating in improved film quality and reinforced device steadiness. Consequently, the best power conversion efficiency (PCE) of the AA-modified Sb2S3 solar cell reached 7.12% (compared to 6.70% for the control), Furthermore, incorporating an additional SnO2 electron transport layer and a BTR-TPA interfacial layer bolstered the efficiency to 7.51%.