Porphyrin-Based Molecular Architectures for Light Energy Conversion

Abstract

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 [D _n P _n ], 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 (η) of OTE/SnO₂/(H₂PC15MPC+C₆₀) _m reaches 1.5%, which is 45 times higher than that of the reference system (0.035%).

Keywords:

• fullerene
• photovoltaic cell
• porphyrin
• supramolecular assembly

Acknowledgments

This work was partially supported by a Grant Aid from the Ministry of Education, Culture, Sports, Science and Technology, Japan. P.V.K. acknowledges the support from the Office of Basic Energy Science of the U.S. Department of Energy. This is contribution no. NDRL 4706 from the Notre Dame Radiation Laboratory and from Osaka University. Figures 1–5 are reproduced from Ref. 15, 17 and 18 with permission of the American Chemical Society and Wiley-VCH.