Dendritic Effects on Structure and Photophysical and Photoelectrochemical Properties of Fullerene Dendrimers and Their Nanoclusters

Abstract

Multifullerene-terminated dendrimers Gn (n ) 1-5) were synthesized and structural, photophysical, and photoelectrochemical properties were studied for the fullerene dendrimers and their nanoclusters. The fullerene dendrimers formed clusters when toluene solutions of the fullerene dendrimers were injected into acetonitrile. Dynamic light scattering and atomic force and scanning electron microscopic measurements on these clusters revealed that the cluster size decreased with increasing the generation number of the dendrimers. The negatively charged clusters were deposited electrophoretically onto a nanostructured SnO 2 -coated ITO electrode by applying DC voltage to the electrode. Photoelectrochemical measurements were carried out in acetonitrile dissolved 0.5 M LiI and 0.01 M I 2 with the standard three electrodes containing the fullerene dendrimermodified SnO 2 working electrode, a platinum wire as a counter electrode, and I -/I 3 -as a reference electrode. An incident photon-to-photocurrent efficiency of the dendrimer photoelectrochemical devices increased with increasing the generation number. Such a close relationship between the structure and photophysical and photoelectrochemical properties of the fullerene dendrimers and their nanoclusters will provide knowledge of photophysics regarding photoactive molecular assemblies with dendritic architectures.

Flower‐Shaped Supramolecular Assemblies: Hierarchical Organization of a Fullerene Bearing Long Aliphatic Chains

“…However, controlling the morphology and size of the superstructures is not well understood. A recent report showed that the morphology of self‐organized clusters of various dendritic fullerenes has an influence on their macroscopic properties, such as the size‐dependent photovoltaic response 7. Recently, we explored the polymorphism of fullerene assemblies by using the two different intermolecular forces, namely π–π interactions of C 60 and van der Waals interactions of aliphatic chains 8.…”

Synthetic Strategies towards Fullerene-Rich Dendrimer Assemblies

“…The whole series of t-butyl-protected dendrons have been subject of photoelectrochemical measurements. Preliminary experiments by injection of toluene solutions containing the appropriate dendron into acetonitrile resulted in the formation of large clusters in the solvent mixture [30]. The order of the mean diameters was not consistent with that of their molecular sizes ranging from 790 nm for (29) m to 90 nm for (36) m .…”

Donor−Acceptor Nanoarchitecture on Semiconducting Electrodes for Solar Energy Conversion

“…66 The IPCE value of the SnO 2 /(4) m devices was increased with increasing the generation number. The maximum IPCE value of 6% in the SnO 2 /(4e) m device was achieved at 400 nm at an applied potential of 0.11 V vs SCE.…”

“…However, the IPCE value was not improved relative to that of the SnO 2 /(4) m device. 66 This may result from the rather large steric congestion around the C 60 moieties of 4, rendering it difficult to yield suitable complexation between the porphyrin and C 60 within 4.…”