This research focuses on the first demonstration of NO2Lw (2-hydroxy-3-nitronaphthalene-1,4-dione) as a photosensitizer
and TiO2, ZnO, and Nb2O5 as photoanode
materials for dye-sensitized solar cells (DSSCs). The metal-free organic
photosensitizer (i.e., nitro-group-substituted naphthoquinone, NO2Lw) was synthesized for this purpose. As a photoanode material,
metal oxides, such as TiO2, ZnO, and Nb2O5, were selected. The synthesized NO2Lw contains
an electron-withdrawing group (−NO2) and anchoring
groups (−OH) that exhibit absorption in the visible range.
The UV–visible absorbance spectrum of NO2Lw demonstrates
the absorption ascribed to ultraviolet and visible region charge transfer.
The NO2Lw interacts with the TiO2, ZnO, and
Nb2O5 photoanode, as shown by bathochromic shifts
in wavelengths in the photosensitizer-loaded TiO2, ZnO,
and Nb2O5 photoanodes. FT-IR analysis also studied
the bonding interaction between NO2Lw and TiO2, ZnO, and Nb2O5 photoanode material. The TiO2, ZnO, and Nb2O5 photoanodes loaded
with NO2Lw exhibit a shift in the wavenumber of the functional
groups, indicating that these groups were involved in loading the
NO2Lw photosensitizer. The amount of photosensitizer loading
was calculated, showing that TiO2 has higher loading than
ZnO and Nb2O5 photoanodes; this factor may constitute
an increased J
SC value of the TiO2 photoanode. The device performance is compared using photocurrent–voltage
(J–V) curves; electrochemical
impedance spectroscopy (EIS) measurement examines the device’s
charge transport. The TiO2 photoanode showed higher performance
than the ZnO and Nb2O5 photoanodes in terms
of photoelectrochemical properties. When compared to ZnO and Nb2O5 photoanodes-based DSSCs, the TiO2 photoanode Bode plot shows a signature frequency peak corresponding
to electron recombination rate toward the low-frequency region, showing
that TiO2 has a greater electron lifetime than ZnO and
Nb2O5 photoanodes based DSSCs.
