We describe the functionalization of single-wall carbon nanotubes (SWNTs) with 4-(2-trimethylsilyl)ethynylaniline and the subsequent attachment of a zinc-phthalocyanine (ZnPc) derivative using the reliable Huisgen 1,3-dipolar cycloaddition. The motivation of this study was the preparation of a nanotube-based platform which allows the facile fabrication of more complex functional nanometer-scale structures, such as a SWNT-ZnPc hybrid. The nanotube derivatives described here were fully characterized by a combination of analytical techniques such as Raman, absorption and emission spectroscopy, atomic force and scanning electron microscopy (AFM and SEM), and thermogravimetric analysis (TGA). The SWNT-ZnPc nanoconjugate was also investigated with a series of steady-state and time-resolved spectroscopy experiments, and a photoinduced communication between the two photoactive components (i.e., SWNT and ZnPc) was identified. Such beneficial features lead to monochromatic internal photoconversion efficiencies of 17.3% when the SWNT-ZnPc hybrid material was tested as photoactive material in an ITO photoanode.

In the present work, a new family of pyrene (Py)-substituted phthalocyanines (Pcs), i.e., ZnPc-Py and H(2)Pc-Py, were designed, synthesized, and probed in light of their spectroscopic properties as well as their interactions with single-wall carbon nanotubes (SWNTs). The pyrene units provide the means for non-covalent functionalization of SWNTs via π-π interactions. Such a versatile approach ensures that the electronic properties of SWNTs are not impacted by the chemical modification of the carbon skeleton. The characterization of ZnPc-Py/SWNT and H(2)Pc-Py/SWNT has been performed in suspension and in thin films by means of different spectroscopic and photoelectrochemical techniques. Transient absorption experiments reveal photoinduced electron transfer between the photoactive components. ZnPc-Py/SWNT and H(2)Pc-Py/SWNT have been integrated into photoactive electrodes, revealing stable and reproducible photocurrents with monochromatic internal photoconversion efficiency values for H(2)Pc-Py/SWNT as large as 15 and 23% without and with an applied bias of +0.1 V.

Exfoliation of graphite was achieved using a zinc phthalocyanine oligomer that is also an electron donor. The resulting functionalized graphene material was investigated by Raman and electron spectroscopy and was trialed in a photoelectrochemical cell.

Four novel nanographene/porphyrin hybrids were prepared, characterized, and probed in solar energy conversion schemes. Exfoliation of graphite by means of immobilizing four different porphyrins onto the basal plane of graphene is accompanied by distinct electronic interactions in both the ground and the excited states. In the ground state, a strong loss in oscillator strength goes hand-in-hand with a notable broadening of the porphyrin transitions and, as such, attests to the shift of electron density from the electron donating porphyrins to nanographene. In the excited state, a nearly quantitative quenching of the porphyrin fluorescence is indicative of full charge transfer. The latter is corroborated by femtosecond transient absorption measurements, which reveal the generation of the one-electron oxidized radical cation of the porphyrins with absorption maxima at 490 and 625 nm in the visible region and conduction band electrons in nanographene with features at 890 and 1025 nm in the near infrared region. We have demonstrated the applicability of the new nanographene/porphyrin hybrids in, for example, solar cells. In this regard, the presence of flakes is crucial in terms of influencing the injection processes, preventing aggregation, and reducing recombination losses, which are commonly encountered in porphyrin-based DSSCs.

In this fundamental study, the supramolecular interactions between SWNTs and either symmetrical Zn(II) octa-tert-butylazulenocyanine 1 or a Zn(II) azulenocyanine-phthalocyanine 2 bearing a pyrene unit have been evaluated. The synthetic protocol allowed for the preparation of unsymmetrical azulenocyanine-phthalocyanine molecules, which incorporate reactive hydroxyl functional groups useful for the preparation of more elaborate derivatives, that is, the pyrene containing derivative 2 by an esterification reaction. To shed light onto the mutual interactions between 1 or 2 and SWNT, stable suspensions of SWNT in a mixture of 25% THF and 75% DMF were titrated with variable amounts of 1 or 2. These assays indicate a successful immobilization of azulenocyanine derivatives 1 or 2 onto SWNTs to yield the supramolecular hybrids SWNT/1 and SWNT/2. In this light, the physico-chemical properties of 1 and 2 as well as those of SWNT/1 and SWNT/2 were investigated. From these we conclude strong interactions in the ground state, and a rapid charge separation in the excited state of SWNT/1 or SWNT/2. The accordingly formed radical ion pair states decay with lifetimes of 124 and 137 ps for SWNT/1 and SWNT/2, respectively. Finally, SWNT/1 and SWNT/2 were integrated into photoelectrochemical cells, revealing a response throughout the visible and near-infrared with a moderate IPCE maxima of 2.5%.

Die Exfoliation von Graphit gelang mithilfe eines Zink‐Phthalocyanin‐Oligomers, das gleichzeitig elektronische Wechselwirkungen aufbaut. Das resultierende funktionalisierte Graphenmaterial wurde mithilfe von Raman‐ und Elektronenspektroskopie untersucht und versuchsweise in einer photoelektrochemischen Zelle eingesetzt.

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