Energy Transfer among Three Dye Components in a Nanosheet–Dye Complex: An Approach To Evaluating the Performance of a Light-Harvesting System

Abstract

Energy transfer among three dye components, namely, p-2,4,5,7-tetrakis(N-methylpyridinium-4-yl)-6-potassium-oxy-3-fluorone (Fluorone), meso-tetra(N-methyl-3-pyridyl) porphine (m-TMPyP), and meso-tetra(N-methyl-4-pyridyl)porphine (p-TMPyP), was investigated for the purpose of utilizing a wide range of sunlight wavelengths for clay nanosheets. In this paper, we define a new parameter, the enhancement ratio of the excitation frequency (Γ380–780 nm) of the dye, in order to comprehensively represent the performance of the light-harvesting system (LHS). Γ380–780 nm is defined as the enhancement ratio of the excitation frequency of dye that has the lowest excitation energy in the system (p-TMPyP in this system) in terms of the frequency of p-TMPyP without the use of light-harvesting dyes (Fluorone and m-TMPyP), when the visible-light region of sunlight (380–780 nm) is used for irradiation light. Γ380–780 nm was calculated from the absorption spectra of dyes, the results of energy transfer experiments, and the sunlight spectrum (380–780 nm). We found that Γ380–780 nm in our LHS is 2.4, which implies enhancement of the excitation frequency of p-TMPyP by 2.4 times relative to that of p-TMPyP without a light harvesting system. We believe that Γ380–780 nm is an important standard parameter of the performance of artificial LHSs.