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β‐Functionalized Push–Pull Porphyrin Sensitizers in Dye‐Sensitized Solar Cells: Effect of π‐Conjugated Spacers
Author(s) -
Ishida Masatoshi,
Hwang Daesub,
Zhang Zhan,
Choi Yung Ji,
Oh Juwon,
Lynch Vincent M.,
Kim Dong Young,
Sessler Jonanthan L.,
Kim Dongho
Publication year - 2015
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201500085
Subject(s) - porphyrin , dye sensitized solar cell , conjugated system , photochemistry , chemistry , energy conversion efficiency , intramolecular force , electrolyte , polymer chemistry , materials science , organic chemistry , polymer , electrode , optoelectronics
A series of new β‐functionalized push–pull‐structured porphyrin dyes were synthesized so as to investigate the effect of the π‐conjugated spacer on the performance of dye‐sensitized solar cells (DSSCs). Suzuki‐ and Heck‐type palladium‐catalyzed coupling methodologies were used to obtain various β‐functionalized porphyrins and β‐benzoic acid (ZnPH n ) and β‐vinylbenzoic acid (ZnPV n ) derivatives from β‐borylated porphyrin precursors. Photophysical studies of the resulting porphyrins revealed a clear dependence on the nature of the β linker. In particular, it was found that a β‐vinylene linkage perturbs the electronic structure of the porphyrin core; this is less true for a β‐phenyl linkage. Theoretical analyses provided support for the intrinsic intramolecular charge‐transfer character of the β‐functionalized, push–pull porphyrins of this study. The extent of charge transfer depends on the nature of the β‐conjugated linkage. The photovoltaic performances of the cells sensitized with β‐phenylenevinylene ZnPV n exhibited higher power conversion efficiency values than those bearing β‐phenyl linkages (ZnPH n ). This was ascribed to differences in light‐harvesting efficiency. Furthermore, compared to the use of a standard iodine‐based electrolyte, the DSSC performance of cells made from the present porphyrins was improved by more than 1 % upon using a cobalt(II/III)‐based electrolyte. Under standard AM 1.5 illumination, the highest efficiency, 8.2 %, was obtained by using cells made from the doubly β‐butadiene‐linked porphyrin.