  Understanding mechanisms in DSSCs is fundamental for their improvement; this
includes the nanocrystalline semiconducting layer behaviour. Different
mesoporous TiO2 layers are fabricated and analyzed for possible use in DSSC
solar cells. The preparations included the addition of P123 triblock copolymer
as structuring agent to the synthesized anatase sol. This preparation was also
mixed with Degussa P25 nanoparticles in one case and polystyrene latex in
another. Mesoporous mixed TiO2-SiO2 thin layers were also analyzed. The diverse
morphology and features are studied by microscopic techniques and by means of
spectral quantum efficiency of a photoelectrochemical cell (PEC) that uses as
photoelectrode the unsensitized porous TiO\_2 layer. Contact angle measurements
are also performed. We have found that a very high specific area due to very
small nanocrystals and small pores can hinder electrolyte penetration in the
pores formed by TiO\_2 nanograins, affecting photoelectrodes efficiency.
