Effect of the Preparation Procedure on the Morphology of Thin TiO2 Films and Their Device Performance in Small-Molecule Bilayer Hybrid Solar Cells

Flat titanium dioxide films, to be used as the acceptor layer in bilayer hybrid solar cell devices, were prepd. by spray pyrolysis and by spin casting. Both prepn. methods resulted in anatase titania films with similar optical and electronic properties but considerably different film morphologies. Spray pyrolysis resulted in dense TiO2 films grown onto and affected by the surface roughness of the underlying conducting glass substrates. The spin-casting prepn. procedure resulted in nanoporous titania films. Hybrid solar cell devices with varying layer thickness of the small-mol. semiconducting dye TDCV-TPA were investigated. Devices built with spray-pyrolyzed titania substrates yielded conversion efficiencies up to 0.47%. Spin-cast titania substrates exhibited short circuits for thin dye layer thickness. For thicker dye layers the performance of these devices was up to 0.6% due to the higher interfacial area for charge sepn. of these nanoporous TiO2 substrates.