The transport and recombination properties of dye-sensitized solar cells based on phase-pure anatase and brookite nanomaterials are compared as a function of the surface chemistry and morphology. Phase-pure brookite has been synthesized from amorphous TiO2 using two different solutions at low and high pH, resulting in different size and morphology of brookite nanoparticles. The smaller short-circuit current density (JSC = 6.6 mA cm–2) for acidic brookite compared to anatase (9.8 mA cm–2) was related to the light harvesting efficiency because of the lower amount of dye adsorbed. However, a larger open-circuit voltage for acidic brookite indicates the promise of the material. The basic brookite-based solar cells gave a very low JSC (0.10 mA cm–2), which increased dramatically by a factor of about 30 after an acid treatment of the films, illustrating the effect of surface chemistry. A combination of experiments shows that the improvement is related to an increase in injection efficiency. Electrochemical impe...