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Table 3
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DH dye
Voc (V)
Jsc (mA/cm2)
ff
h (%)
DH-1
DH-2
DH-3
N719
0.69
0.59
0.56
0.61
6.85
5.56
4.45
0.63
0.65
0.63
0.57
3.00
2.13
1.58
4.86
14.04
electron-withdrawing 1,2,3-triazole group does favor the spatial
charge separation in DH dyes. Thus, all DSSCs based on DH dyes
show a relatively high Voc value. Especially, the Voc value of DH-1-
based cell is even higher than that of the N719-based cell. However,
the Jsc values of the DH dye cells are far from the N719-based cell
device. The narrow absorption band of DH dyes is the crux of the
problem. In addition, the electron-withdrawing 1,2,3-triazole
structure, which seems to favor enhancing Voc value, possibly
hinders the electron injection into the CB of TiO2 that is adverse to
the generation of photocurrent. Indeed, from the point of view of
practical application, DH dyes are not panchromatic, since only
a narrow part of the solar spectrum is absorbed. However, this
situation can be improved through modifying the structure such as
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to extend
p
-backbone in this similar family of dyes. The structural
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Three new metal-free organic dyes (DH-1, DH-2 and DH-3)
composed with different branched numbers of anchoring groups
have been synthesized through a convenient ‘Click’ reaction. The
introduction of the 1,2,3-triazole unit is favorable for the charge
separation of the DH dyes, which can effectively suppress the
charge recombination and increase the Voc and fill factor of DH-
based DSSCs. However, the introduction of more branched struc-
ture in the DH dyes makes the molecular polarity decrease that
leads to the narrow and blue-shifted absorption and is unfavorable
for the DSSCs performance. This work provides beneficial infor-
mation for developing similar families of new organic dyes for
DSSCs.
Acknowledgments
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coumarin dyes for stable and efficient organic dye-sensitized solar cells. J Phys
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We are grateful to the National Natural Science Foundation of
China (Nos. 20972122 and 20774071) and the Specialized Research
Fund for the Doctoral Program of Higher Education of China (No.
20100141110010) for financial support.
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