Transport parameters determining thickness homogeneity and deposition time in multi-objective optimization of CuS-covellite SILAR coatings

abstract

Semiconductor films play a key role in technological applications such as solar cells, photocatalysis, and smart windows. In the latter, covellite phase CuS deposited by SILAR stands out as a promising material for low-emissivity applications. However, long deposition times and the need for homogeneous films pose challenges to process scalability and coating applications in architectural windows. In this work, a mathematical metamodel was used to simulate the CuS-covellite film deposition via SILAR and simultaneously optimize thickness, homogeneity, and deposition time. Four input variables related to substrate transport were defined: immersion speed, emersion speed, transfer speed, and distance between solutions. Through an iterative process, four rounds of experiments demonstrated that the input variables significantly influence film growth and quality. Emersion speed was found to dominate variations in thickness and homogeneity; at low emersion speed, the effects of the other variables are mitigated. Optimized transport parameters were determined to be 14.75 mm/s, 3 mm/s, 39 mm/s, and 55 mm for immersion speed, emersion speed, transfer speed, and distance between solutions, respectively. These values enabled a film thickness of 96.19 nm in 3.35 h with a homogeneity of 5 % across the deposition area. Our results highlight the importance of controlling transport parameters in the SILAR method and demonstrate how metamodels allow evaluation of multiple variables, even when data is limited. These findings are expected to enhance reproducibility in the literature and support the transition from laboratory synthesis to industrial scaling of semiconductor films developed by SILAR for solar control applications. © 2025 Elsevier B.V.