Graphene nanocomposites
have emerged as potential photoanode materials
for increased performance of the dye-sensitized solar cells (DSSCs)
via charge transfer. Various metal-oxide-decorated graphene nanocomposites
have widespread applications in energy devices, such as solar cells,
fuel cells, batteries, sensors, electrocatalysis, and photocatalysis.
However, the possible role of these composites in DSSC applications
has largely remained unexplored. Herein, we studied a Sb2O3-decorated graphene–D−π1–π2–A sensitized TiO2 nanocomposite
(dye-(TiO2)9/Sb2O3@GO)
as a model multi-junction light-harvesting system and examined the
impact of various π-bridges on the optical and photovoltaic
properties of the push–pull dye system employed in this light-harvesting
system. We have shown that by changing the spacer unit, the light
sensitivity of nanocomposites can be varied from visible to near-infrared
wavelengths. Furthermore, with the integration of metal-oxide-decorated
graphene nanocomposites on D−π1–π2–A systems and D−π–A systems, composite
photoelectrodes displayed better optical and photovoltaic characteristics
with an enhanced absorption spectrum in the wavelength range of 800–1000
nm. The performance of the D−π1–π2–A system has been evaluated in terms of various photovoltaic
parameters such as the highest occupied molecular orbital–lowest
unoccupied molecular orbital energy gaps, excited-state oxidation
potential (E
dye
*), free energy of electron injection (G
inject), total reorganization energy (λtotal), and open-circuit voltage (V
oc). This work throws light on the current trends and the future opportunities
in graphene–metal oxide nanocomposite-based DSSCs for better
harvesting of the solar spectrum and better performance of solar devices.