Photoinjection of High Potential Holes into Cu5Ta11O30 Nanoparticles by Porphyrin Dyes

Excited-state hole injection into the valence band of Cu5Ta11O30 nanoparticles (NP-Cu5Ta11O30) was investigated through sensitization with zinc porphyrin dyes using simulated solar irradiance. The Cu5Ta11O30 nanoparticles were prepared by a flux-mediated synthesis and found to have an average particle size of ∼10–15 nm by DLS and TEM. The zinc 4-(10,15,20-tris­(4-pyridinyl)-porphin-5-yl)­phenyl­phos­phonic acid (D1) and its analogue, in which the pyridine groups are methylated (D2), were synthesized and found to have excited-state reduction potentials appropriate for p-type dye sensitization of the nanoparticles. The dye-sensitized NP-Cu5Ta11O30 exhibited fluorescence quenching consistent with electron transfer from the NP-Cu5Ta11O30 to the dye; forward and recombination rates were obtained by transient absorption measurements. Hole injection times of 8 ps and