Dye-sensitized solar cell based on an inclusion complex of a cyclic porphyrin dimer bearing four 4-pyridyl groups and fullerene C60Electronic supplementary information (ESI) available: 1H NMR and 13C NMR for compounds 1, 2 and H4-C4-CPDPy(TEO). See DOI: 10.1039/c6ra01131d

• Main Authors: Ooyama, Yousuke, Uenaka, Koji, Kamimura, Takuya, Ozako, Shuwa, Kanda, Masahiro, Koide, Taro, Tani, Fumito
• Format: Journal Article
• Published: 08.02.2016
• ISSN: 2046-2069
• DOI: 10.1039/c6ra01131d

Cyclic free-base porphyrin dimers ( H 4 -C 4 -CPD Py (TEO) and H 4 -Ptz-CPD Py (TEO) ) linked by butadiyne or phenothiazine bearing four 4-pyridyl groups and their inclusion complexes ( C 60 ⊂H 4 -C 4 -CPD Py (TEO) and C 60 ⊂H 4 -Ptz-CPD Py (TEO) ) with fullerene C 60 have been applied to dye-sensitized solar cells (DSSCs) as a new class of porphyrin dye sensitizers with pyridyl anchoring groups for attachment on a TiO 2 electrode. The FTIR spectra of the porphyrin dimers adsorbed on TiO 2 nanoparticles demonstrated that these porphyrin dimers are adsorbed on the TiO 2 surface through the formation of hydrogen bonding of pyridyl groups and/or pyridinium ions at Brønsted acid sites on the TiO 2 surface. The adsorption amount of the porphyrin dimers adsorbed on the TiO 2 electrode is 2.0 × 10 17 molecules per cm 2 , that is, the adsorption amount of the porphyrin unit is 4.0 × 10 17 cm −2 , which is higher than that of dye sensitizers with pyridyl groups reported so far. The photovoltaic performance of DSSCs based on phenothiazine-bridged cyclic porphyrin dimer H 4 -Ptz-CPD Py (TEO) is higher than that of DSSCs based on butadiyne-linked cyclic porphyrin dimer H 4 -C 4 -CPD Py (TEO) . Moreover, the photovoltaic performances of DSSCs based on cyclic free-base porphyrin dimers are higher than those of DSSCs based on their C 60 inclusion complexes C 60 ⊂H 4 -C 4 -CPD Py (TEO) and C 60 ⊂H 4 -Ptz-CPD Py (TEO) . On the basis of the electrochemical measurements (voltammetry and electrochemical impedance spectroscopy) and the transient absorption spectroscopy, the differences in the photovoltaic performances among these cyclic free-base porphyrin dimers are discussed from kinetic and thermodynamic considerations concerning the electron transfer processes in DSSCs. Cyclic free-base porphyrin dimers linked by butadiyne or phenothiazine bearing four 4-pyridyl groups and their inclusion complexes with fullerene C 60 have been applied to dye-sensitized solar cells as a new class of porphyrin dye sensitizers.