Versatile 1-D Nanostructures for Green Energy Conversion …
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like structures suffer from large charge carrier recombination losses as the charge
carrier has to cross many grain boundaries. When light falls on 1-D nanostructured
arrays, it undergoes diffuse scattering as shown in Fig. 4c, which reduces the reflection
losses and boosts the light harvesting.
To manifest all these beneficial properties of 1-D nanostructures in PSC, scientists
have developed various 1-D nanostructures and have successfully applied in various
types of solar cells. Corresponding literature survey is given in Table 1.
The 1-D nanostructures, like nanoribbons, nanorods, nanobelts, and so on, of
ZnO, TiO 2 , CdO, CdSe, and so on have proven to be beneficial for solar cells because
they easily provide large surface to volume ratios, facile surface functionalization,
high aspect ratios, and superior stabilities owing to perfect crystallinities (Kamble
et al. 2014). Considering all the benefits mentioned above, we have synthesized
1-D nanostructures of various materials, like ZnO, TiO 2 , CdSe, CdO, CdO–ZnO
composite and so on, by cost-effective and green chemical route. The synthesis
of nanostructures is often carried out with environmentally hazardous and toxic
chemicals, like olylamine, dodecanthiol, octadecene, hydrazene hydrate and so on.
Here we have synthesized 1-D nanostructures of various materials by simple, nonvacuum, low temperature and scalable green chemical route.
The ZnO nanorods are synthesized by hydrothermal technique at 90 °C. We have
studied the effect of hydroxide anion generating agents like hexamine and ammonia.
Earlier it was believed that hexamine plays a key role in 1-D growth of ZnO, but
through our work we have shown that with the use of ammonia also one can grow 1D ZnO nanostructures with high aspect ratio and shorter reaction time as compared
to hexamine (Kamble et al. 2014). Figure 5a depicts the uniform growth of high
aspect ratio ZnO nanorods array with rod diameter in range 20–60 nm and length in
few micrometers. The cross-sectional image in Fig. 5b and very high intensity XRD
peak of (002) plane (Fig. 5c) gives an idea of large aspect ratio of synthesized ZnO
nanorod arrays.
Synthesized ZnO nanorod arrays are successfully applied in photoelectrochemical solar cells. We also have fabricated 1-D core/shell nanostructures
of ZnO–CdS for fabrication of semiconductor sensitized solar cell (SSSC) (Kamble
et al. 2015a, b). The ZnO–CdS core/shell structure based on 1-D ZnO facilitates
the maximum light harvesting and reduced recombination losses; all the details of
synthesis and solar cell performance are given in our research articles (Kamble et al.
2015a, b).
Considering the remarkable physico-chemical properties of 1-D TiO 2 , such as
high optical transmittance in the visible–IR spectral range, high chemical stability,
mechanical resistance, efficient electron transporter and self-cleaning property, 1D TiO 2 is widely used in various applications like perovskite solar cells, DSSC,
QDSSC, photocatalysis, sensors, self-cleaning materials, Li-ion battery and so on
(Bian et al. 2014; Giannuzzi et al. 2014; Liu et al. 2008; Mali et al. 2017).
Various techniques found to be used for the synthesis of 1-D TiO 2 , like electrochemical anodization, AAO template-assisted deposition, CVD, sol–gel and so
on. Among all these techniques, the precise control over size and shape can be
achieved through hydrothermal technique. Not only the TiO 2 nanorods but also the
337
like structures suffer from large charge carrier recombination losses as the charge
carrier has to cross many grain boundaries. When light falls on 1-D nanostructured
arrays, it undergoes diffuse scattering as shown in Fig. 4c, which reduces the reflection
losses and boosts the light harvesting.
To manifest all these beneficial properties of 1-D nanostructures in PSC, scientists
have developed various 1-D nanostructures and have successfully applied in various
types of solar cells. Corresponding literature survey is given in Table 1.
The 1-D nanostructures, like nanoribbons, nanorods, nanobelts, and so on, of
ZnO, TiO 2 , CdO, CdSe, and so on have proven to be beneficial for solar cells because
they easily provide large surface to volume ratios, facile surface functionalization,
high aspect ratios, and superior stabilities owing to perfect crystallinities (Kamble
et al. 2014). Considering all the benefits mentioned above, we have synthesized
1-D nanostructures of various materials, like ZnO, TiO 2 , CdSe, CdO, CdO–ZnO
composite and so on, by cost-effective and green chemical route. The synthesis
of nanostructures is often carried out with environmentally hazardous and toxic
chemicals, like olylamine, dodecanthiol, octadecene, hydrazene hydrate and so on.
Here we have synthesized 1-D nanostructures of various materials by simple, nonvacuum, low temperature and scalable green chemical route.
The ZnO nanorods are synthesized by hydrothermal technique at 90 °C. We have
studied the effect of hydroxide anion generating agents like hexamine and ammonia.
Earlier it was believed that hexamine plays a key role in 1-D growth of ZnO, but
through our work we have shown that with the use of ammonia also one can grow 1D ZnO nanostructures with high aspect ratio and shorter reaction time as compared
to hexamine (Kamble et al. 2014). Figure 5a depicts the uniform growth of high
aspect ratio ZnO nanorods array with rod diameter in range 20–60 nm and length in
few micrometers. The cross-sectional image in Fig. 5b and very high intensity XRD
peak of (002) plane (Fig. 5c) gives an idea of large aspect ratio of synthesized ZnO
nanorod arrays.
Synthesized ZnO nanorod arrays are successfully applied in photoelectrochemical solar cells. We also have fabricated 1-D core/shell nanostructures
of ZnO–CdS for fabrication of semiconductor sensitized solar cell (SSSC) (Kamble
et al. 2015a, b). The ZnO–CdS core/shell structure based on 1-D ZnO facilitates
the maximum light harvesting and reduced recombination losses; all the details of
synthesis and solar cell performance are given in our research articles (Kamble et al.
2015a, b).
Considering the remarkable physico-chemical properties of 1-D TiO 2 , such as
high optical transmittance in the visible–IR spectral range, high chemical stability,
mechanical resistance, efficient electron transporter and self-cleaning property, 1D TiO 2 is widely used in various applications like perovskite solar cells, DSSC,
QDSSC, photocatalysis, sensors, self-cleaning materials, Li-ion battery and so on
(Bian et al. 2014; Giannuzzi et al. 2014; Liu et al. 2008; Mali et al. 2017).
Various techniques found to be used for the synthesis of 1-D TiO 2 , like electrochemical anodization, AAO template-assisted deposition, CVD, sol–gel and so
on. Among all these techniques, the precise control over size and shape can be
achieved through hydrothermal technique. Not only the TiO 2 nanorods but also the