Ethynyl-linked push-pull porphyrin hetero-dimers for near-IR dye-sensitized solar cells: photovoltaic performances versusexcited-state dynamics

Ethynyl-linked porphyrin hetero-dimers substituted by a series of electron donors, namely, bis(4-methoxyphenyl)amino (BMPA), bis(4-tert-butylphenyl)amino (BTBPA) and 3,6-di-tert-butylcarbazol-9-yl (DTBC) as well as a reference dimer with a non-donor moiety (3,5-di-tert-butylphenyl, DTBP) have been s...

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Published in:Physical chemistry chemical physics : PCCP 2012-11, Vol.14 (48), p.16703-16712
Main Authors: Liu, Yizhu, Lin, Hong, Li, Jianbao, Dy, Joanne Ting, Tamaki, Koichi, Nakazaki, Jotaro, Nakayama, Daisuke, Nishiyama, Chie, Uchida, Satoshi, Kubo, Takaya, Segawa, Hiroshi
Format: Article
Language:English
Subjects:
Arrays
Density
Differential scanning calorimetry
Dyes
Photoelectric effect
Photovoltaic cells
Porphyrins
Solar cells
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Summary:Ethynyl-linked porphyrin hetero-dimers substituted by a series of electron donors, namely, bis(4-methoxyphenyl)amino (BMPA), bis(4-tert-butylphenyl)amino (BTBPA) and 3,6-di-tert-butylcarbazol-9-yl (DTBC) as well as a reference dimer with a non-donor moiety (3,5-di-tert-butylphenyl, DTBP) have been synthesized to systematically investigate the influence of donor introduction on the photovoltaic performances of near-IR dye-sensitized solar cells (DSCs) with these sensitizers incorporated. Despite the expected bathochromic shift and intensification of long-wavelength absorption bands as well as elevated LUMO levels and thus increased electron injection driving forces, the substitution of diphenylamino groups (BMPA and BTBPA) with stronger electron-donating abilities gave rise to surprising mediocrity in the short-circuit photocurrent densities (J sub(sc)), leading to overall energy conversion efficiencies in the order BMPA (3.94%) < DTBP (4.57%) < BTBPA (4.83%) < DTBC (5.21%). A study of the in situfluorescent behavior of these sensitizers revealed that for all the sensitizers, excited-state lifetimes were significantly shortened in the simulated DSC environment compared to those in a free solution. BMPA showed the shortest intrinsic in situlifetime while DTBC showed the longest one. These results were correlated with the photovoltaic performances, which is required for a better understanding and further design of porphyrin array sensitizers.
ISSN:1463-9076
1463-9084
DOI:10.1039/c2cp43165c