40
T. Maeda
Fig. 2.25 Squaraine dyes used as electron donor materials for bulk heterojunction solar cells
2PA molecules (Ceymann Rosspeintner et al. 2006). These multiple chromophoric
systems based on squaraines exhibited a large 2PA cross section.
Furthermore, squaraine dyes were one of the substantial candidates for electron
donor materials used in organic photovoltaics because their prominent absorption
and electron-donating nature is proved by their high oxidation potentials (Chen et al.
2015). Dyes 42 and 43 show a certain level of performance in the bulk heterojunction solar cells using fullerene derivative, (6,6)-phenyl C 61 butyric acid methyl ester
(PCBM) as electron acceptor materials (Fig. 2.25) (Mayerhöffer et al. 2009; Wei
et al. 2011). Pagani et al. reported pyrrole-based squaraines 44 for donor materials
(Silvestri et al. 2008).
The intense absorption in the far-red and near-infrared region of squaraine is
also useful for the sensitizers of dye-sensitized solar cells. Unsymmetrical squaraine
sensitizer consisting of triphenylamine-thiophene and carboxy indolenine components 45 was synthesized and used for the sensitizer for TiO 2 -based dye-sensitized
solar cells (Li et al. 2010). The cell shows panchromatic response, thanks to the broad
absorption band of 45 on TiO 2 . Dyes 46 in which the cyanoacryl group is attached
to the squaraine chromophores through rigid π-conjugated spacers were synthesized
by catalytic cross-coupling reaction as a key reaction using the corresponding halogenated squaraine dye as substrate. These dyes have high performance as sensitizers
in dye-sensitized solar cells (Fig. 2.26) (Shi et al. 2011b; Jradi et al. 2015).
Squaraine dye 47 with branch structure was synthesized by the Sonogashira
coupling between triarylamine with ethynyl groups and iodinated squaraines. It is also
applied to the sensitizers in dye-sensitized solar cells (Fig. 2.27) (Nguyen et al. 2016).
Fig. 2.26 Squaraines with peripheral donor components designed for dye-sensitized solar cells
T. Maeda
Fig. 2.25 Squaraine dyes used as electron donor materials for bulk heterojunction solar cells
2PA molecules (Ceymann Rosspeintner et al. 2006). These multiple chromophoric
systems based on squaraines exhibited a large 2PA cross section.
Furthermore, squaraine dyes were one of the substantial candidates for electron
donor materials used in organic photovoltaics because their prominent absorption
and electron-donating nature is proved by their high oxidation potentials (Chen et al.
2015). Dyes 42 and 43 show a certain level of performance in the bulk heterojunction solar cells using fullerene derivative, (6,6)-phenyl C 61 butyric acid methyl ester
(PCBM) as electron acceptor materials (Fig. 2.25) (Mayerhöffer et al. 2009; Wei
et al. 2011). Pagani et al. reported pyrrole-based squaraines 44 for donor materials
(Silvestri et al. 2008).
The intense absorption in the far-red and near-infrared region of squaraine is
also useful for the sensitizers of dye-sensitized solar cells. Unsymmetrical squaraine
sensitizer consisting of triphenylamine-thiophene and carboxy indolenine components 45 was synthesized and used for the sensitizer for TiO 2 -based dye-sensitized
solar cells (Li et al. 2010). The cell shows panchromatic response, thanks to the broad
absorption band of 45 on TiO 2 . Dyes 46 in which the cyanoacryl group is attached
to the squaraine chromophores through rigid π-conjugated spacers were synthesized
by catalytic cross-coupling reaction as a key reaction using the corresponding halogenated squaraine dye as substrate. These dyes have high performance as sensitizers
in dye-sensitized solar cells (Fig. 2.26) (Shi et al. 2011b; Jradi et al. 2015).
Squaraine dye 47 with branch structure was synthesized by the Sonogashira
coupling between triarylamine with ethynyl groups and iodinated squaraines. It is also
applied to the sensitizers in dye-sensitized solar cells (Fig. 2.27) (Nguyen et al. 2016).
Fig. 2.26 Squaraines with peripheral donor components designed for dye-sensitized solar cells