“…The maximum absorption wavelength (λ max ) is exhibited at 439, 438, and 427 nm for NO 2 Lw-loaded TiO 2 , ZnO, and Nb 2 O 5 photoanodes, respectively. The NO 2 Lw-loaded TiO 2, ZnO, and Nb 2 O 5 photoanodes show the redshift in the visible region, confirming the formation of complexation between NO 2 Lw and TiO 2 , ZnO, and Nb 2 O 5 photoanodes, which demonstrates the sufficient amount of photosensitizer adsorbed on the TiO 2 , ZnO, and Nb 2 O 5 surfaces. , …”
Section: Resultsmentioning
confidence: 63%
“…The NO 2 Lw-loaded TiO 2, ZnO, and Nb 2 O 5 photoanodes show the redshift in the visible region, confirming the formation of complexation between NO 2 Lw and TiO 2 , ZnO, and Nb 2 O 5 photoanodes, which demonstrates the sufficient amount of photosensitizer adsorbed on the TiO 2 , ZnO, and Nb 2 O 5 surfaces. 117 , 118 …”
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.
“…The maximum absorption wavelength (λ max ) is exhibited at 439, 438, and 427 nm for NO 2 Lw-loaded TiO 2 , ZnO, and Nb 2 O 5 photoanodes, respectively. The NO 2 Lw-loaded TiO 2, ZnO, and Nb 2 O 5 photoanodes show the redshift in the visible region, confirming the formation of complexation between NO 2 Lw and TiO 2 , ZnO, and Nb 2 O 5 photoanodes, which demonstrates the sufficient amount of photosensitizer adsorbed on the TiO 2 , ZnO, and Nb 2 O 5 surfaces. , …”
Section: Resultsmentioning
confidence: 63%
“…The NO 2 Lw-loaded TiO 2, ZnO, and Nb 2 O 5 photoanodes show the redshift in the visible region, confirming the formation of complexation between NO 2 Lw and TiO 2 , ZnO, and Nb 2 O 5 photoanodes, which demonstrates the sufficient amount of photosensitizer adsorbed on the TiO 2 , ZnO, and Nb 2 O 5 surfaces. 117 , 118 …”
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.
“…It has also been observed that there is no additional notable peak appeared in the spectra of doped material, which shows a good agreement of rare-earth metal in the host material. As the absorption is related to excitation and is dependent on the electron population, the UV or VIS response regions for all materials may vary significantly 27 . Figure 6 ( a ) UV–Vis diffuse reflectance spectra of synthesized bare/doped BiFeO 3 , ( b ) UV–Vis diffuse absorbance spectra of synthesized bare/doped BiFeO 3 , ( c ) Tauc plots against[F(R)*hv] 2 versus hv (eV), and ( d ) Photoluminescence spectra of synthesized bare/doped BiFeO 3 .…”
Section: Resultsmentioning
confidence: 99%
“…6, wherein high reflectance peaks were shown by Nd-doped BiFeO 3 and Pr-doped BiFeO 3 , while low reflectance peaks were shown by Gd-doped It has also been observed that there is no additional notable peak appeared in the spectra of doped material, which shows a good agreement of rare-earth metal in the host material. As the absorption is related to excitation and is dependent on the electron population, the UV or VIS response regions for all materials may vary significantly 27 . Moreover, the Tauc plot given in Fig.…”
This study reports light energy harvesting characteristics of bismuth ferrite (BiFeO3) and BiFO3 doped with rare-earth metals such as neodymium (Nd), praseodymium (Pr), and gadolinium (Gd) dye solutions that were prepared by using the co-precipitation method. The structural, morphological, and optical properties of synthesized materials were studied, confirming that 5–50 nm sized synthesized particles have a well-developed and non-uniform grain size due to their amorphous nature. Moreover, the peaks of photoelectron emission for bare and doped BiFeO3 were observed in the visible region at around 490 nm, while the emission intensity of bare BiFeO3 was noticed to be lower than that of doped materials. Photoanodes were prepared with the paste of the synthesized sample and then assembled to make a solar cell. The natural and synthetic dye solutions of Mentha, Actinidia deliciosa, and green malachite, respectively, were prepared in which the photoanodes were immersed to analyze the photoconversion efficiency of the assembled dye-synthesized solar cells. The power conversion efficiency of fabricated DSSCs, which was confirmed from the I–V curve, is in the range from 0.84 to 2.15%. This study confirms that mint (Mentha) dye and Nd-doped BiFeO3 materials were found to be the most efficient sensitizer and photoanode materials among all the sensitizers and photoanodes tested.
“…The red shift toward the longer wavelength in the visible region for all sensitizer-loaded TiO 2 photoanodes confirms the formation of complexation between the sensitizer and TiO 2 , which shows the sufficient amount of the sensitizer adsorb on the TiO 2 surface. 47,48 The UV−visible absorbance spectra of all three sensitizers show the absorption in ultraviolet and visible-region bands assigned to π → π* and n → π* charge transfer, respectively. 49 The absorption data for bare TiO 2 were analyzed, and the TiO 2 band gap was 3.2 eV.…”
Naphthoquinoneoxime derivatives, viz., LwOx, 3-hydroxy-4-(hydroxyimino)naphthalen-1
(4H)-one; PthOx, 3-hydroxy-4-(hydroxyimino)-2-methylnaphthalen-1(4H)-one; and Cl_LwOx, 2-chloro-3-hydroxy-4-(hydroxyimino)naphthalen-1(4H)-one, are used in fabrication of dye-sensitized solar
cells (DSSCs). The photophysical and electrochemical properties of
the sensitizers were studied. The HOMO–LUMO energy gaps of
the sensitizers (LwOx, PthOx, and Cl_LwOx) calculated by using the
intersection of UV–visible and fluorescence spectra are 2.85,
2.71, and 2.87 eV, respectively. The energy band alignment energy
level of the sensitizer, that is, the lowest unoccupied molecular
orbital (LUMO) and highest occupied molecular orbital (HOMO), should
match with the energy level of the TiO2 conduction band
and the redox potential of iodine/triiodide electrolyte to allow smooth
electron transfer. The electrochemical characterization of sensitizers
was done to find the LUMO and HOMO level of the sensitizer. It shows
that the LUMO level of (LwOx, PthOx, and Cl_LwOx) is above the conduction
band position of TiO2. Electrochemical impedance spectroscopy
was used to study the charge transport resistance and electron lifetime
of DSSCs. The charge transport resistance at the TiO2
|electrolyte|counter electrode interface was
reduced in the Cl_LwOx device; thus, the electron lifetime of Cl_LwOx
was enhanced compared to LwOx and PthOx sensitizers. The fabricated
device was characterized using photocurrent density–voltage
(J–V) measurement. It is
observed that there was an enhancement in the overall power conversion
efficiency (η) of the DSSCs fabricated by using Cl_LwOx sensitizers
as compared to LwOx and PthOx sensitizer-loaded photoanodes. Enhancement
in power conversion efficiency, that is, photovoltage and photocurrent,
is achieved due to the chlorine substituent. Thus, the chlorine substituent
naphthoquinoneoxime pushes the electron density, enhancing the pushing
nature and facilitating the lone pair present in the N–OH moiety
to attach to TiO2 more strongly.
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