(Invited) Electron Donor-Nanocarbon Electron Acceptor Composites Linked with Oligophenylene Bridge

Abstract

During the last few decades, considerable efforts have been made toward the construction of donor–acceptor (D–A) linked systems that efficiently cause photoinduced charge separation, a fundamental step in natural photosynthesis and solar energy conversion. Among the building units for such D–A systems, nanocarbons deserve a special mention because it shows notable electronic conductivity, tenacious mechanical strength, and huge specific surface area. These singular properties place nanocarbon-based D–A systems in an attractive position as the next-generation material for energy-conversion devices such as solar fuels and organic photovoltaics. With this in mind, a variety of studies have been done to synthesize covalently linked systems of electron-accepting nanocarbons with electron-donating units such as pyrenes, porphyrins and phthalocyanines. However, the D–A interface frequently undergoes a rapid relaxation of the partially charge-separated (CS) exciplex or the completely CS state to the ground state, failing to generate a long-lived CS state that is crucial for solar energy conversion. In-depth understanding of the correlation between the structure and photodynamics of the electron donor-nanocarbon electron acceptor linked systems is important for extracting the full potential of such D–A materials for the potential applications. In this talk I will show an overviw of our recent achievements related with photodynamics of pyrene- and porphyrin-attached chemically converted graphenes linked with oligophenylene bridge. [1] T. Umeyama, J. Baek, Y. Sato, K. Suenaga, F. Abou-Chahine, N. V. Tkachenko, H. Lemmetyinen, and H. Imahori, Nat. Commun., 6, 7732 (2015). [2] T. Umeyama, J. Baek, J. Mihara, N. V. Tkachenko, and H. Imahori, Chem. Commun., in press. [3] T. Umeyama, T. Hanaoka, J. Baek, T. Higashino, F. Abou-Chahine, N. V. Tkachenko, and H. Imahori, J. Phys. Chem. C, in press.