This paper presents the development and optimization of dye-sensitized solar cells (DSSCs) using nanocrystalline rutile TiO₂ films. The authors, N.-G. Park, J. van de Lagemaat, and A. J. Frank from the National Renewable Energy Laboratory, describe the preparation and characterization of crack-free rutile TiO₂ films up to 12 μm thick. These films were compared with conventional anatase-based DSSCs in terms of their photoelectrochemical properties. Scanning electron microscopy and intensity-modulated photocurrent spectroscopy revealed that electron transport is slower in the rutile layer due to differences in inter-particle connectivity and particle packing density. Despite these challenges, the photovoltaic response of the rutile-based DSSC is comparable to that of the anatase-based cell, highlighting the potential of rutile TiO₂ for commercial applications. The study discusses possible improvements to enhance photocurrent and electron transport rates in rutile films.This paper presents the development and optimization of dye-sensitized solar cells (DSSCs) using nanocrystalline rutile TiO₂ films. The authors, N.-G. Park, J. van de Lagemaat, and A. J. Frank from the National Renewable Energy Laboratory, describe the preparation and characterization of crack-free rutile TiO₂ films up to 12 μm thick. These films were compared with conventional anatase-based DSSCs in terms of their photoelectrochemical properties. Scanning electron microscopy and intensity-modulated photocurrent spectroscopy revealed that electron transport is slower in the rutile layer due to differences in inter-particle connectivity and particle packing density. Despite these challenges, the photovoltaic response of the rutile-based DSSC is comparable to that of the anatase-based cell, highlighting the potential of rutile TiO₂ for commercial applications. The study discusses possible improvements to enhance photocurrent and electron transport rates in rutile films.