Inertial impaction and surface diffusion-assisted rapid dye molecule adsorption on TiO2 thin films for highly efficient dye-sensitized solar cells

An effective and versatile single-stage aerosol impactor was specially designed to rapidly coat the surface of TiO2 thin films with a controlled amount of dye molecules via inertial impaction and surface diffusion to speed-up the manufacturing process and enhance the photovoltaic performance of dye-sensitized solar cells (DSSCs). By theoretically determining the specific dimensions of the aerosol accelerating nozzle and experimentally controlling the mixing ratio between the sheath gas and dye aerosol flow rates in the single-stage aerosol impactor, the speed and quality of dye adsorption on the TiO2 thin films of the photoelectrodes could be systematically assessed in terms of the photovoltaic performance of the DSSCs, including open-circuit voltage, short-circuit current, fill factor, and power conversion efficiency (PCE). It was found that the aerosol impactor-assisted dye coating method developed in this study significantly reduced the duration of dye adsorption (aerosol coating duration = 20-60 min) and increased the PCE of the DSSCs to 7.28%. Using this methodology, dye-coating was ∼20 times faster and the fabricated device has 23% higher PCE compared to the DSSC fabricated by the conventional dip coating method (dip-coating duration = 1200 min, PCE = 5.92%). These results proved that the single-stage aerosol impactor designed in this study is a very effective and versatile device for rapidly coating the surface of TiO2 thin films with dye molecules using sufficient inertial impaction, which enables the introduced dye molecules to infiltrate and quickly adsorb on the surface of TiO2 nanoparticles accumulated in the DSSC photoelectrodes.