Antenna for light harvesting

Antennae for light harvesting Reaction centre for charge separation Membrane for physical separation... 

Figure 20. Schema ic representation of an artificial antenna for light harvesting.

An antenna for light harvesting is an organized multicomponent system, in which an array of chromophoric molecules absorbs the incident light and channels the excitation energy to the common acceptor components [49-57], The antenna effect... 

Generally speaking, an antenna for light harvesting is an organized multicomponent system in which several chro-mophoric molecular species absorb the incident light and channel the excitation energy to a common acceptor component. Artificial antenna systems based on porphyrin arrays [63], multichromophoric cyclodextrins [64], polynuclear metal complexes [65, 66], dendrimers [66-68], and polymers [69, 70] have been reported. In all these systems, the chromophoric units are connected by means of covalent... 

Figure 1. Schematic representation of the artificial photosynthetic reaction center by a monolayer assembly by A-S-D triad and antenna molecules for light harvesting (H), lateral energy migration and energy transfer, and charge separation across the membrane via multistep electron transfer (a) Side view of mono-layer assembly, (b) top view of a triad surrounded by H molecules, and (c) energy diagram for photo-electric conversion in a monolayer assembly.

We reported the preparation of sophisticated bipolar three-dye photonic antenna materials for light harvesting and transport [22]. The principle is illustrated in Figure 1.12. Zeolite L microcrystals of cylinder morphology are used as host for organizing several thousand dyes as monomers into well-defined zones. 

The two cationic dyes, Py+ as a donor and Ox" as an acceptor, were found to be very versatile for demonstrating photonic antenna functionalities for light harvesting, transport, and capturing, as illustrated in Fig. 7. They can be incorporated into zeolite L by means of ion exchange, where they are present as monomers because of the restricted space. In this form they have a high fluorescence quantum yield and favourable spectral properties. The insertion of the dyes can be visualised by means of fluorescence microscopy. The fluorescence anisotropy of Ox -loaded zeolite L has recently been investigated in detail by conventional and by confocal microscopy techniques [15],... 

Calzaferri G, Pauchard M, Maas H, Huber S, Khatyr A, Schaafsma T. Photonic antenna system for light harvesting, transport and trapping. / Mater Chem 2002 12 1-13. 

Schematic representation of a photosynthetic reaction center in a molecular assembly with an A/S/D triad and an antenna molecule (H) for light harvesting Energy diagram for energy transfer and... 

Figure 8. Antenna-sensitizer molecular devices for light harvesting in photoelectrochemical cells...

Fig. 31 Schematic representation of the artificial photosynthetic reaction center by a monolayer assembly of antenna (H) and A-S-D triad molecules for light harvesting, energy migration and transfer, and charge separation via multistep electron transfer.

The antenna system is thus a way for nature to increase the cross section for light harvesting of sunlight for the same RC. One single RC can take care of excitations from a large number of antenna chromophores, and carry out charge separation. 

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