Dispersion stability and drying behavior of colloidal silica

Colloidal suspensions containing nano-sized particles are used in numerous applications such as batteries, inks and paints, and also used as precursors to a wide variety of industrial materials. The ability to control the microstructure during drying is important for many potential applications. When it comes to solar cell technology, controlling the microstructure plays a critical role ranging from thin film solar cell (where no void in the film is desirable) to dye-sensitized solar cell (where void is desired to produce small pores). For instance, Copper-Indium-Selenide solar cell, or more commonly known as CIS solar cell requires smooth surfaces and uniform microstructure. In those applications non-uniform particle aggregation is a critical defect to be avoided. In this sense, drying process of colloidal suspension is a crucial step that often determines final coating quality. While there have been many studies on liquid states and final film structures of colloidal system, the mechanism of drying process is not fully understood yet. In this study, we investigate drying process of colloidal suspension by examining its microstructure.