Diameter-sorted SWCNT-porphyrin and SWCNT-phthalocyanine conjugates for light-energy harvesting

Atula S.D. Sandanayaka, Navaneetha K. Subbaiyan, Sushanta K. Das, Raghu Chitta, Eranda Maligaspe, Taku Hasobe, Osamu Ito, Francis D'Souza

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Abstract

A non-covalent double-decker binding strategy is employed to construct functional supramolecular single-wall carbon nanotubes (SWCNT)-tetrapyrrole hybrids capable of undergoing photoinduced electron transfer and performing direct conversion of light into electricity. To accomplish this, two semiconducting SWCNTs of different diameters (6,5 and 7,6) were modified via π-π stacking of pyrene functionalized with an alkyl ammonium cation (PyrNH3+). Such modified nanotubes were subsequently assembled via dipole-cation binding of zinc porphyrin with one (1) or four benzo-18-crown-6 cavities (2) or phthalocyanine with four benzo-18-crown-6 cavities at the ring periphery (3), employed as visible-light photosensitizers. Upon charactering the conjugates using TEM and optical techniques, electron transfer via photoexcited zinc porphyrin and phthalocyanine was investigated using time-resolved emission and transient absorption techniques. Higher charge-separation efficiency is established for SWCNT(7,6) with a narrow band gap than the thin SWCNT(6,5) with a wide band gap. Photoelectrochemical studies using FTO/SnO2 electrodes modified with these donor-acceptor conjugates unanimously demonstrated the ability of these conjugates to convert light energy into electricity. The photocurrent generation followed the trend observed for charge separation, that is, incident-photon-to-current efficiency (IPCE) of a maximum of 12% is achieved for photocells with FTO/SnO 2/SWCNT(7,6)/PyrNH3+:1.

Original languageEnglish
Pages (from-to)2266-2273
Number of pages8
JournalChemPhysChem
Volume12
Issue number12
DOIs
Publication statusPublished - 2011 Aug 22

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Keywords

  • crown ethers
  • electron transfer
  • nanotubes
  • photoelectrochemistry
  • self-assembly

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

Cite this

Sandanayaka, A. S. D., Subbaiyan, N. K., Das, S. K., Chitta, R., Maligaspe, E., Hasobe, T., Ito, O., & D'Souza, F. (2011). Diameter-sorted SWCNT-porphyrin and SWCNT-phthalocyanine conjugates for light-energy harvesting. ChemPhysChem, 12(12), 2266-2273. https://doi.org/10.1002/cphc.201100377