Faculty Publications
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Item Exploring the application of new carbazole based dyes as effective p-type photosensitizers in dye-sensitized solar cells(Elsevier Ltd, 2017) Naik, P.; Planchat, A.; Pellegrin, Y.; Odobel, F.; Vasudeva Adhikari, A.V.Herein, we report the design and the synthesis of three new D-A type metal-free carbazole based dyes (C1–3) as effective photosensitizers for p-type DSSCs. In this new design, the electron rich carboxy substituted carbazole unit has been attached to three different electron withdrawing species, viz. N,N-dimethyl barbituric acid, N,N-diethyl thiobarbituric acid and N-ethyl rhodanine. They were well-characterized by spectral, photophysical and electrochemical analyses. Further, their optical and electrochemical parameters along with molecular geometries, optimized from DFT have been employed to apprehend the effect of structures of C1–3 on their photovoltaic performances. Further, the photovoltaic performance of C1–3 was determined along with the standard dye P1 and their PCE values were found to be in the order of P1 (0.047%) > C2 (0.040%) > C1 (0.016%) > C3 (0.001%). Interestingly, the NiO based p-type DSSC fabricated with C2 carrying electron withdrawing N,N-diethyl thiobarbituric acid displayed VOC as 59 ± 4 mV and FF as 29 ± 1%, which are higher than that of benchmark reference P1. This is attributed to the highest light harvesting ability, the greatest regeneration driving force and the lowest interfacial charge recombination of C2 among the tested dyes. Conclusively, the results showcase the potential of carbazole based D-A type sensitizers in the development of efficient p-type DSSCs. © 2017 Elsevier LtdItem Synthesis and photovoltaic performance of a novel asymmetric dual-channel co-sensitizer for dye-sensitized solar cell beyond 10% efficiency(Elsevier Ltd, 2017) Babu, D.D.; Su, R.; Naik, P.; El-Shafei, A.; Vasudeva Adhikari, A.V.In this paper, we report the design and synthesis of a new bi-anchoring indole based co-sensitizer DBA-8 with A-?-D-A (acceptor-? bridge-donor-acceptor) architecture, carrying indole moiety as a donor and barbituric acid as acceptor/anchoring groups. Its photo-physical and electrochemical properties along with molecular geometries, calculated from Density Functional Theory (DFT) are employed to comprehend the effect of co-sensitizer structure on photovoltaic characteristics of DSSCs. The abovementioned organic dye (DBA-8) was employed as a co-sensitizer along with well-known ruthenium based sensitizer NCSU-10 in order to broaden the spectral responses of the co-sensitized DSSC. In the present work, for the first time we are demonstrating the profound role of a dual-anchoring co-sensitizer that can play in ameliorating the overall performance of a solar cell. The photovoltaic studies indicated that, the co-sensitizer DBA-8 succeeded in increasing the light harvesting ability in the device significantly. Notably, the device co-sensitized using 0.2 mM DBA-8 along with ruthenium based chromophore NCSU-10, showed a maximum efficiency of 10.68% (Jsc = 25.14 mAcm?2, Voc = 0.695 V, ff = 61.2%). Further, the good agreement between the theoretically and experimentally obtained ?max data vindicate that, the energy functional and basis set employed in this study can be successfully utilized for predicting the absorption spectra of new photosensitizers, with great precision before synthesis. Furthermore, all these findings showcase the vast potential of bi-anchoring molecules in improving the overall performance of the dye-sensitized solar cells. © 2017 Elsevier LtdItem New carbazole based dyes as effective co-sensitizers for DSSCs sensitized with ruthenium (II) complex (NCSU-10)(Elsevier B.V., 2018) Naik, P.; Su, R.; Elmorsy, M.R.; El-Shafei, A.; Vasudeva Adhikari, A.V.Herein, we report the design and synthesis of three new D–A type metal-free carbazole based dyes (S1–3) as effective co-sensitizers for dye-sensitized solar cell (DSSC) sensitized with Ru(II) complex (NCSU-10). In this new design, the electron rich carbazole unit was attached to three different electron withdrawing/anchoring species, viz. 4-amino benzoic acid, sulfanilic acid and barbituric acid. The dyes were characterized by spectral, photophysical and electrochemical analysis. Their optical and electrochemical parameters along with molecular geometries, optimized from DFT have been employed to apprehend the effect of the structures of these co-sensitizers on the photovoltaic performances. Further, S1–3 dyes were co-sensitized along with a well-known NCSU-10 dye in order to broaden the spectral response of the co-sensitized devices and hence improve the efficiency. The photovoltaic performance studies indicated that, the device fabricated using S1 dye as co-sensitizer with 0.2 mM of NCSU-10 exhibited improved PCE of 9.55% with JSC of 22.85 mA cm?2, VOC of 0.672 V and FF of 62.2%, whereas the DSSC fabricated with dye NCSU-10 (0.2 mM) alone displayed PCE of 8.25% with JSC of 20.41 mA cm?2, VOC of 0.667 V and FF of 60.6%. Furthermore, electronic excitations simulated using time-dependent DFT, were in good agreement with the experimentally obtained results of the co-sensitizers, indicating that the exchange-correlation function and basis set utilized for predicting the spectra of the co-sensitizers are quite appropriate for the calculations. In conclusion, the results showed the potential of simple organic co-sensitizers in the development of efficient DSSCs. © 2017 Science PressItem A simple D-A-?-A configured carbazole based dye as an active photo-sensitizer: A comparative investigation on different parameters of cell(Elsevier B.V., 2020) Babu, D.D.; Naik, P.; Keremane, K.S.An organic photosensitizer (DP-1) with D-A-?-A architecture was systematically analyzed along with our previously reported dye N1. In the design, the dyes carry carbazole as donor, thiophene acetonitrile as ?-spacer connected to varied acceptor/anchoring unit i.e., cyanoacrylic acid (N1) and 4-aminobenzoic acid (DP-1). Generally, cyanoacrylic acid and carboxyl groups have been investigated extensively as effective electron acceptor/anchoring unit for the design of the sensitizer for dye-sensitized solar cells (DSSC) application and displayed superior photon conversion efficiency. In the present work, both the dyes were taken up for various studies focusing on photophysical, electrochemical, theoretical and photovoltaic investigation in the corresponding solar cells. From the photophysical and electrochemical studies it was established that, the both dyes show upright thermodynamic feasibility for electrochemical processes in the cell i.e., both electron and dye regeneration. Also, the DFT studies appends the existence of feasible HOMO-LUMO charge distribution. Finally, the devices fabricated by employing these dyes as sensitizer with 10 mM DCA as co-adsorbent. The device based on N1 displayed improved photon conversion efficiency compared to the cell sensitized using DP-1. This work may provide a new strategy for designing efficient photosensitizers to further ameliorate the DSSCs performance. © 2020 Elsevier B.V.Item Push-pull carbazole twin dyads as efficient sensitizers/co-sensitizers for DSSC application: effect of various anchoring groups on photovoltaic performance(Royal Society of Chemistry, 2025) Keremane, K.S.; Abdellah, I.M.; Eletmany, M.R.; Naik, P.; Anees, P.; Vasudeva Adhikari, A.V.To investigate the effect of various anchoring groups of organic sensitizers on fundamental processes occurring inside DSSCs and their overall performance, we designed and synthesized nine new double donor-acceptor (D-A) type organic dyes DCH1-9 comprising carbazole-based twin molecules as electron donors, with a non-conjugated linear alkyl chain as an extended linker featuring multiple acceptor units. Their photophysical, thermal, electrochemical, and theoretical properties were examined to gain a deeper understanding of the structure-property relationship. Photophysical results revealed that all dyes display ?abs and ?emi in the range of 400-470 nm and 500-560 nm, respectively, with a bandgap in the range of 2.46-2.74 eV. The push-pull structure with extended conjugation results in strong fluorescence characteristics. Photophysical and electrochemical studies confirm their thermodynamic feasibility for electron injection, recombination, and dye regeneration in cells. Quantum chemical simulations further provided insights into their structural, electronic, and optical parameters. New DSSCs were fabricated employing dyes DCH1-9 as sensitizers/co-sensitizers. The cell sensitized with DCH1 achieved the highest power conversion efficiency (PCE) of 2.45% under standard AM 1.5 solar conditions. Furthermore, co-sensitization of DCH1-9 with the Ru-based HD-2 sensitizer resulted in an improved PCE of 8.82% for DCH2, surpassing HD-2 alone (6.79%). EIS studies were conducted to further explore their energy conversion processes. Conclusively, these investigations highlight the significant potential of dyes carrying carbazole twin molecules with different anchoring units in enhancing the overall performance of DSSCs. © 2025 The Royal Society of Chemistry.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.