On fundamental mechanisms in dye sensitized solar cells through the behaviour of different mesoporous titanium dioxide films

TL;DR

This study investigates how different mesoporous TiO2 films affect the performance of dye-sensitized solar cells, revealing that very high surface area nanocrystals can hinder electrolyte penetration and reduce efficiency.

Contribution

It introduces new fabrication methods for mesoporous TiO2 layers with varied morphologies and analyzes their impact on DSSC performance.

Findings

High specific surface area can hinder electrolyte penetration.

Different mesoporous structures influence photoelectrode efficiency.

Mixed TiO2-SiO2 layers show varied morphological features.

Abstract

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.