Faculty Publications
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Item Push-Pull Phenoxazine-Based Sensitizers for p-Type DSSCs: Effect of Acceptor Units on Photovoltaic Performance(John Wiley and Sons Inc, 2022) Keremane, K.S.; Planchat, A.; Pellegrin, Y.; Jacquemin, D.; Odobel, F.; Vasudeva Adhikari, A.Finding new efficient p-type sensitizers for NiO photocathodes is a great challenge for the development of promising low-cost tandem dye-sensitized solar cells (DSSCs). Now, the focus of researchers investigating these cells has been to create high-performance p-type systems. With this intention, herein, the design and synthesis of six new phenoxazine-based donor–acceptor (D–A)-configured organic dyes PO1–6 was reported, comprising different acceptor moieties specially designed for the sensitization of mesoporous p-type semiconductor NiO for the construction of p-type DSSCs (p-DSSCs). This work includes structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies of these dyes, including evaluation of their structure-property relationships. The optical studies revealed that PO1–6 displayed adequate absorption and emission features in the range of 480–550 and 560–650 nm, respectively, with a bandgap in the order of 2.05–2.40 eV, and their thermodynamic parameters favored an efficient interfacial charge transfer involving NiO. Among the six new dyes, the device based on sensitizer PO2 carrying electron-withdrawing 1,3-diethyl-2-thiobarbituric acid achieved the highest power conversion efficiency of 0.031 % (short-circuit current density=0.89 mA cm−2, open-circuit voltage=101 mV, and fill factor=35 %). Conclusively, the study furnishes an understanding of the intricacies involved in the structural modification of phenoxazine-based sensitizers to further ameliorate the performance of the p-type DSSCs. © 2022 Wiley-VCH GmbH.Item Anionic Fluorine and Cationic Niobium Codoped Tin Oxide Thin Films as Transparent Conducting Electrodes for Optoelectronic Applications(John Wiley and Sons Inc, 2023) Reddivari, R.; Reddy, N.P.; Santhosh, R.; Maharana, G.; Fernandes, J.M.; Padmanaban, D.B.; Kovendhan, M.; Veerappan, G.; Laxminarayana, G.; Murali, M.; Joseph, D.P.Exploration of alternatives for supplementing indium tin oxide electrode is currently trending due to scarcity of indium, leading to a steep increase in the cost of related optoelectronic components. Codoping of niobium (Nb) and fluorine (F) into SnO2 lattice as cationic and anionic dopants, respectively, is explored by spray deposition technique. A fixed 10 wt% F and varying Nb concentration from 0 to 5 wt% is incorporated into the SnO2 lattice. X-ray diffraction reveals substitution of Nb and F into the SnO2 lattice without altering the structure. Optical transmittance is found to increase with Nb content up to 4% of Nb (77.59%), and it decreases thereafter. Scanning electron microscope and optical profiler imply a relatively smooth surface with sharp-tipped particles which vary with Nb concentration. Sheet resistance decreases up to 3 wt% of Nb doping and increases thereafter. Contact angle measurement indicates that upon doping with Nb, the films turn hydrophilic. Among the deposited films, 4 wt% of Nb-doped film shows the highest figure of merit of 5.01 × 10−3 Ω−1. The surface work function of the 4 wt% Nb-doped SnO2 film is 4,687.85 meV. The optimal films are tested as electrodes in dye-sensitized solar cells and are discussed in detail. © 2023 Wiley-VCH GmbH.Item Efficiency enhancement in dye-sensitized solar cells through neodymium-doped graphene quantum dot-modified TiO? photoanodes(Elsevier B.V., 2025) Senadeera, G.K.R.; Weerasekara, W.M.S.K.; Jaseetharan, T.; Sandunika, P.U.; Kumari, J.M.K.W.; Dissanayake, M.A.K.L.; Muhiuddin, M.; Rahman, M.R.; Bhat K, U.; Akhtar, M.W.; Udayakumar, U.; Siddique, A.B.; Ekanayake, P.This study explored the effects of Neodymium-doped graphene quantum dots (NdGQDs) on improving the performance efficiency of TiO2 based dye-sensitized solar cells (DSSCs). By employing in-situ physical assisted mixing, DSSCs with optimized NdGQDs in TiO2 photoanodes showed a power conversion efficiency of 8.76 %, a significant improvement compared to the 6.01 % efficiency of pristine TiO2-based DSSCs under 100 mW cm?2 illumination (AM 1.5). Notably, the short-circuit current density increased by 74 %. HRTEM analysis revealed that the NdGQDs have a size range of approximately 7–9 nm. UV–visible spectroscopy and Mott-Schottky analysis revealed a positive shift in the Fermi level, promoting better electron transfer and increased photocurrent density at the expenses of the open circuit voltage. Electrochemical impedance spectroscopy characterization of DSSCs incorporating NdGQD-modified photoanodes revealed a reduction in electron transfer resistance at the photoanode|dye|electrolyte interface, accompanied by an increase in recombination resistance within the device suppressing the electron recombination rate. © 2024 Elsevier B.V.Item New carbazole-based symmetric double D–A type chromophores for DSSC application: Impact of di-anchoring nature on photoelectrochemical processes(Elsevier B.V., 2025) Keremane, K.S.; Eletmany, M.R.; Abdellah, I.M.; Naik, P.; Vasudeva Adhikari, A.V.Herein, we report the systematic molecular design, synthesis, and characterization of a new series of carbazole-based organic dyes with a symmetric double donor–acceptor configuration, bearing seven different acceptor units as potential photosensitizers. The new molecules consist of strong electron-donating carbazole twin molecules linked together by a linear alkyl chain (C5H10) and attached to the various anchoring units, viz. cyanoacetic acid (DCP1), rhodanine-3-acetic acid (DCP2), rhodanine (DCP3), 1,3-dimethylbarbituric acid (DCP4), barbituric acid (DCP5), 1,3-diethyl-2-thiobarbituric acid (DCP6), and 4-nitrophenyl acetonitrile (DCP7). We performed structural, photophysical, thermal, electrochemical, and theoretical studies to assess the role of the dual anchoring nature of the chromophores on photoelectrochemical processes and their suitability as photosensitizers. The optical results revealed that all the dyes display ?abs and ?emi in the 404–465 nm and 503–556 nm range, respectively, with a bandgap of 2.44–2.70 eV. Furthermore, we have successfully fabricated new Dye-Sensitized Solar Cells (DSSCs) using dyes DCP1–7 as photosensitizers. Among them, DCP1 achieved the power conversion efficiency (PCE) of ?2 % under standard AM 1.5 solar conditions. Also, electrochemical impedance spectroscopy (EIS) has been carried out to investigate electronic and ionic processes within the cell. Conclusively, these studies showcase the significant potential of carbazole twin molecules with various anchoring units in improving the overall performance of DSSCs. © 2025 Elsevier B.V.Item Enhancing the Photoelectrochemical Performance of Ru(II)-Sensitized Dye-Sensitized Solar Cells Using Cyanopyridine-Based Cosensitizers(John Wiley and Sons Inc, 2025) Naik, P.; Abdellah, I.M.; Abdel-Shakour, M.; Keremane, K.S.; Vasudeva Adhikari, A.V.The cosensitization approach is one of the widely adopted strategies for systematically enhancing photovoltaic performance of dye-sensitized solar cells (DSSCs) by utilizing two or more dyes with distinct absorption spectra. This method achieves panchromatic absorption, improves intramolecular charge transfer performance, prevents dye aggregation, and increases dye loading capability. In this study, we investigated four previously reported push–pull-type dianchored chromophores (CP1–4) featuring a cyanopyridine scaffold as cosensitizer to enhance the performance of Ru(II)-based N3-sensitized DSSCs. Both the co-sensitized devices (N3 + CP1–4) and the N3-only devices were fabricated using a fixed dye concentration of 0.2 mM for each sensitizer/cosensitizers, while the coadsorbent chenodeoxycholic acid (CDCA) was systematically varied between 0 and 20 mM. This systematic variation of CDCA concentration was designed to examine its role in suppressing dye aggregation and modulating interfacial charge dynamics. Among the Series, CP4, carrying a thiobarbituric acid anchoring/acceptor group, demonstrated superior performance at all CDCA concentrations, achieving power conversion efficiency of 6.67%, 6.79%, and 5.74%, compared to 6.02%, 6.10%, and 5.44% for devices sensitized with N3 alone. Further, electrochemical impedance spectroscopy measurements confirmed the improved charge transport and reduced recombination in these devices. These findings highlight the potential of rationally engineered cosensitizers and optimized coadsorbent concentrations for enhancing the performance of metal-based sensitizers in DSSCs. © 2025 Wiley-VCH GmbH.