298
J. B. Liyanage et al.
efficiency of 4.90% has been obtained after optimizing the amount of GaN used in
the composite mixture, which is an increase of about 60% when compared with that
of a DSC of pure P25 nanoparticles. Here the photovoltaic performance has increased
due to the decrease in charge transfer resistance and the increase in charge recombination resistance, at the electrolyte/dye/semiconductor interface (Huang et al. 2014).
Another metal nitride composite that has been studied is titanium nitride (TiN)
with TiO 2 . Higher content of TiN has shown a higher absorption of visible light. The
V OC has been increased as the flat band potential has shifted to a more negative value.
The increase in FF can be attributed to the high conductivity of the film. However,
this system yielded a decrease in J sc which can be due to the low amounts of dye
adsorption. Here an efficiency of 7.27% was observed, which is much higher than
that obtained by simply using a P25 photoanode (Li et al. 2015).
15.3.4 Metal Sulfides
Photovoltaic properties of some metal sulfide-TiO 2 composites have been studied,
several which have shown remarkable potential in solar cell applications. Ding et al.
studied a one step, high temperature, solvothermal method to synthesize TiO 2 -sulfide
nanospheres. They were prepared using the respective hydrated sulfate. The considered composite materials are CdS (Wang et al. 2010), Cu 2 S (Peng et al. 2014),
ZnS (Sadikin et al. 2019) and Co 9 S 8 (Yuan et al. 2017). These sulfide containing
composites absorbed visible light and the high reaction temperature improved the
crystallinity, making the composite mixtures suitable for DSSC application as well
(Ding et al. 2012).
15.3.5 Carbon Nanostructures
Carbonaceous nanomaterials are an economic option to composite with TiO 2 , which
can result in enhanced efficiency of DSCs. The proposed activity of carbonaceous
materials is either by excitation of the carbonaceous compound followed by charge
injection to TiO 2 (Wang et al. 2005) or by formation of a Ti–O–C bond which leads
to the creation of energy states within the band gap of TiO 2 (Pyrgiotakis et al. 2005),
facilitating more efficient light absorption. The mechanism depends on the synthetic
technique used. These composites also show improvement in dye adsorption and
increased electron transport.
One of the most commonly used carbon nanostructures in preparing composites
with TiO 2 are carbon nanotubes (CNT). As they not only have a large electronsstorage capacity, but also can show electronic conductivity similar to that of metals
(Kongkanand et al. 2007). The 1D nano-structure and good electrical conductivity
of CNT are beneficial to transport the electrons within TiO 2 films and enhance their
photocatalytic and photoelectric conversion efficiencies (Yu et al. 2007).
J. B. Liyanage et al.
efficiency of 4.90% has been obtained after optimizing the amount of GaN used in
the composite mixture, which is an increase of about 60% when compared with that
of a DSC of pure P25 nanoparticles. Here the photovoltaic performance has increased
due to the decrease in charge transfer resistance and the increase in charge recombination resistance, at the electrolyte/dye/semiconductor interface (Huang et al. 2014).
Another metal nitride composite that has been studied is titanium nitride (TiN)
with TiO 2 . Higher content of TiN has shown a higher absorption of visible light. The
V OC has been increased as the flat band potential has shifted to a more negative value.
The increase in FF can be attributed to the high conductivity of the film. However,
this system yielded a decrease in J sc which can be due to the low amounts of dye
adsorption. Here an efficiency of 7.27% was observed, which is much higher than
that obtained by simply using a P25 photoanode (Li et al. 2015).
15.3.4 Metal Sulfides
Photovoltaic properties of some metal sulfide-TiO 2 composites have been studied,
several which have shown remarkable potential in solar cell applications. Ding et al.
studied a one step, high temperature, solvothermal method to synthesize TiO 2 -sulfide
nanospheres. They were prepared using the respective hydrated sulfate. The considered composite materials are CdS (Wang et al. 2010), Cu 2 S (Peng et al. 2014),
ZnS (Sadikin et al. 2019) and Co 9 S 8 (Yuan et al. 2017). These sulfide containing
composites absorbed visible light and the high reaction temperature improved the
crystallinity, making the composite mixtures suitable for DSSC application as well
(Ding et al. 2012).
15.3.5 Carbon Nanostructures
Carbonaceous nanomaterials are an economic option to composite with TiO 2 , which
can result in enhanced efficiency of DSCs. The proposed activity of carbonaceous
materials is either by excitation of the carbonaceous compound followed by charge
injection to TiO 2 (Wang et al. 2005) or by formation of a Ti–O–C bond which leads
to the creation of energy states within the band gap of TiO 2 (Pyrgiotakis et al. 2005),
facilitating more efficient light absorption. The mechanism depends on the synthetic
technique used. These composites also show improvement in dye adsorption and
increased electron transport.
One of the most commonly used carbon nanostructures in preparing composites
with TiO 2 are carbon nanotubes (CNT). As they not only have a large electronsstorage capacity, but also can show electronic conductivity similar to that of metals
(Kongkanand et al. 2007). The 1D nano-structure and good electrical conductivity
of CNT are beneficial to transport the electrons within TiO 2 films and enhance their
photocatalytic and photoelectric conversion efficiencies (Yu et al. 2007).