Low-Symmetry Ω-Shaped Zinc Phthalocyanine Sensitizers with Panchromatic Light-Harvesting Properties for Dye-Sensitized Solar Cells.
Chemistry
; 22(52): 18760-18768, 2016 Dec 23.
Article
em En
| MEDLINE
| ID: mdl-27723139
ABSTRACT
Two low-symmetry phthalocyanines (Pcs) substituted with thiophene units at the non-peripheral (α) and peripheral (ß) positions were synthesized and their optical, electronic-structure, and electrochemical properties were investigated. The substitution of thiophene units at the α positions of the phthalocyanine skeleton resulted in a red shift of the Q band and significantly modified the molecular-orbital electronic distributions just below the HOMO and just above the LUMO, with distortion of the typical Gouterman four-orbital arrangement of MOs. Two amphiphilic Ω-shaped ZnPcs (αPcS1 and αPcS2) bearing a π-conjugated side chain with an adsorption site at an α position of the Pc macrocycle were synthesized as sensitizers for dye-sensitized solar cells (DSSCs). The absorption spectra of αPcS1 and αPcS2 showed red shifted Q bands and a broad band from 350 to 550â
nm assignable to the intramolecular charge-transfer transition from the ZnPc core to the side chains. Time-dependent DFT calculations provided a clear interpretation of the effect of the thiophene conjugation on the typical phthalocyanine core π MOs. Compound αPcS1 was used as a light-harvesting dye on a TiO2 electrode for a DSSC, which showed a panchromatic response in the range 400-800â
nm with a power conversion efficiency of 5.5 % under one-sun conditions.
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MEDLINE
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En
Ano de publicação:
2016
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Article