Using Raman spectroscopy to probe the internal structure and excitonic properties of light-harvesting aggregates of tetra (sulfonatophenyl) porphyrin

摘要: Borrowing ideas from light-harvesting aggregates in nature for use in photovoltaics or solar fuels to improve light collection and solar energy efficiency is an attractive prospect. However an incomplete understanding of the aggregate internal structure and its relation to excitonic states hinders the progress in this field. In this work, aggregates of a synthetic porphyrin called tetra (sulfonatophenyl) porphyrin (TSPP) are used as a model system to probe this correlation using resonance Raman spectroscopy. The hypothesized structure for these nanotubular aggregates is that of a hierarchical assembly composed of circular aggregates of TSPP which are held together by electrostatic forces. The formation of the observed nanotube structure then derives from water-mediated hydrogen bonding. Ensemble, condensed phase resonance Raman spectroscopy, single aggregate resonance Raman spectroscopy/microscopy …