Reflux of a solution of [Ti8 O12 (H2 O)24 ]Cl8 ⋅HCl⋅7 H2 O as titanium precursor at 120 °C for 24 h leads to a transparent colloidal solution of nanosized crystallized anatase TiO2 . The adjustment of the particle size and composition of the dispersant is monitored through the initial water content while controlling the conversion of propylene carbonate into propylene glycol during reflux. The solutions were processed as thin films to produce electron transporting layers in hybrid bulk heterojunction solar cells, by using a blend of P3HT:PCBM polymers as absorbers, in inverted architectures. The solutions obtained by reflux were demonstrated to produce suitable electron transporting layers.
Keywords: TiO2 nanoparticles; colloidal solutions; electron transporting layer; organic photovoltaics; reflux process.
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