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.
In a recent study, TiO 2 nanorod electrodes were prepared by the hydrothermal approach followed by calcination at various temperatures from 300 to 600 °C. The effects of calcination temperature on the morphological and structural properties were investigated. The novel analogue of aminonaphthoquinone(2R-(nalkylamino)-1,4-naphthoquinone) photosensitizer, viz. BrA1, 2bromo-3-(methylamino)naphthalene-1,4-dione was synthesized from 2,3-dibromonaphthalene-1,4-dione. X-ray crystallographic data collection and refinement confirm that BrA1 crystallizes in the triclinic space group P1̅ . After loading BrA1, the photosensitizer on the annealed TiO 2 nanorod (TiO 2 NR) electrodes, the optical properties of the photoanodes showed broadbands in each of the UV and visible regions, which are attributed to the π →π* and n → π* charge-transfer transitions, respectively. The dye-sensitized solar cell (DSSC) system was formed by loading the BrA1 photosensitizer on TiO 2 NR. The electrochemical impedance spectroscopy (EIS) analyses confirm that calcination temperature improves the charge transportation by lowering the resistance path during the photovoltaic process in TiO 2 NR (400 °C) photoanode-based DSSCs due to the sufficient photosensitizer adsorption and fast electron injection. Due to the effective light harvesting by the BrA1 photosensitizer and charge transport through the TiO 2 nanorod, the power conversion efficiencies (PCE) of the TiO 2 NR (400 °C/BrA1-based) DSSCs were improved for 2-bromo-3-(methylamino)naphthalene-1,4-dione.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.