Long-lived photoinduced charge separation for solar cell applications in supramolecular complexes of multi-metalloporphyrins and fullerenes

Shunichi Fukuzumi,Kei Ohkubo

doi:10.1039/c3dt51883c

Abstract

Monomers, dimers, trimers, dendrimers and oligomers of metalloporphyrins form supramolecular complexes with fullerene derivatives via electrostatic interactions, π-π interactions and coordination bonds. Photoexcitation of the supramolecular complexes resulted in photoinduced electron transfer from the porphyrin moiety to the fullerene moiety to produce the charge-separated states as revealed by laser flash photolysis measurements. The rate constants of photoinduced charge separation and charge recombination in supramolecular complexes of multi-metalloporphyrins and fullerenes were also determined by laser flash photolysis measurements and the results depending on the number of porphyrins in the supramolecular complexes are discussed in terms of efficiency of photoinduced energy transfer and charge separation as well as the lifetimes of charge-separated states. The photoelectrochemical performances of solar cells composed of supramolecular complexes of monomers, dimers, dendrimers and oligomers of metalloporphyrins with fullerenes are compared in relation to the rate constants of photoinduced charge separation and charge recombination.

Highlights

Photosynthesis is initiated by the multistep electron-transfer reactions in the photosynthetic reaction centres following light energy harvesting by antenna chlorophylls, funnelled to a bacteriochlorophyll
Kei Ohkubo earned his Ph.D. degree from the Graduate School of Engineering, Osaka University in 2001. He was working as a JSPS fellow and a Japan Science and Technology Agency (JST) research fellow at Osaka University from 2001 to 2005
We review our recent development on photoinduced charge separation in supramolecular complexes of porphyrin anions and fullerene cations with electrostatic interactions and those composed of multi-metalloporphyrins and fullerenes, which are strongly bound in polar solvents, towards construction of supramolecular solar cells based on the long-lived photoinduced charge separation

Summary

Introduction

Photosynthesis is one of the most fundamental and indispensable processes in nature, because it converts light energy into chemical energy required to maintain life.[1,2] Photosynthesis is initiated by the multistep electron-transfer reactions in the photosynthetic reaction centres following light energy harvesting by antenna chlorophylls, funnelled to a bacteriochlorophyll.

Supramolecular complex of a porphyrin tripod with C60

Supramolecular complexes of porphyrin oligopeptides and C60

Findings

Conclusions