Porphyrin-based molecular architectures for light energy conversion

We have constructed a series of supramolecular photovoltaic cells composed of multi-porphyrin arrays such as porphyrin-alkanethiolate monolayer protected-gold nanoparticles [H2PCnMPC: n is the number of methylene groups in the spacer], porphyrin dendrimers [DnPn], and porphyrin-peptide oligomers [P(H2P)n] and fullerene (C60) on nanostructured SnO2 electrodes (OTE/SnO2). These multi-porphyrin arrays form complexes with fullerene molecules and they form clusters in acetonitrile/toluene mixed solvent. The highly colored composite clusters are assembled as three-dimensional arrays onto nanostructured SnO2 films [denoted as OTE/SnO2/(multi-porphyrin array+C60)m] using an electrophoretic deposition method. These highly organized molecular assembly films attain drastic enhancement of light energy conversion properties as compared to the non-organized reference system. The maximum power conversion efficiency () of OTE/SnO2/(H2PC15MPC+C60)m reaches 1.5%, which is 45 times higher than that of the reference system (0.035%).