Faculty Publications

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    Structure-Property Evaluation of Knoevenagel-Derived π-Conjugated Organic Systems
    (John Wiley and Sons Inc, 2025) Ravikumar, M.V.; Raj, A.K.; Rajeswara Rao, M.; Lakshmi, V.
    π-Conjugated organic compounds display unique optical and electrical properties, rendering them appropriate for semiconducting applications. Knoevenagel condensation is one of the important reactions that facilitate the formation of olefin linkages (−C=C−) and thus has been widely employed to synthesize new π-conjugated molecules. This review summarizes the synthesis of π-conjugated compounds constructed using four novel π-conjugated moieties: diketonate/azopyrrole-BF2 complexes (BF), p-azaquinodimethane (AQM), diketopyrrolopyrrole (DPP), and barbituric acid (BA), alongside their optoelectronic features and applications in sensing, bioimaging, and photovoltaic technologies. © 2025 Wiley-VCH GmbH.
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    Structurally simple D–A-type organic sensitizers for dye-sensitized solar cells: effect of anchoring moieties on the cell performance
    (Springer Verlag service@springer.de, 2017) Naik, P.; Su, R.; Babu, D.D.; El-Shafei, A.; Vasudeva Adhikari, A.
    Abstract: In this work, we report synthesis and device fabrication studies of four metal-free D–A-type dyes (A1–A4) based on structurally simple N,N-dimethyl-4-vinyl aniline carrying four different acceptor/anchoring groups, as sensitizers for sensitizing photoanode (TiO2). In the sensitizers, N,N-dimethylaniline ring acts as an electron donor, while barbituric acid, N,N-dimethyl barbituric acid, thiobarbituric acid and N,N-diethyl thiobarbituric acid function as electron acceptor/anchoring units. They were synthesized in good yield via Knoevenagel protocol in neutral condition without any catalyst. Further, they were subjected to structural, electrochemical and optical characterization in order to evaluate their structure, band gap and absorption/emission behavior. The studies reveal that all the four dyes have thermodynamic feasibility of electron injection as well as electron recombination; their optical band gaps were found to be in the range of 2.35–2.56 eV. High-quality crystals of A2 and A4 were grown by slow evaporation technique using its solution with 1:1 pet ether (60–80 °C)/ethyl acetate solvent mixture at room temperature. Their SC-XRD studies disclose that the crystals are in the triclinic system with space group P-1. Further, DFT studies were performed using Turbomole V7.1 software package to evaluate their optimized geometry and HOMO and LUMO levels. Finally, DSSC device fabricated with the dye A1 showed relatively good efficiency when compared to other dyes mainly due to the effective binding of barbituric acid on the surface of TiO2 through NH or OH functional group. Graphical Abstract: [Figure not available: see fulltext.]. © 2017, Iranian Chemical Society.
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    Highly efficient carbazole based co-sensitizers carrying electron deficient barbituric acid for NCSU-10 sensitized DSSCs
    (Elsevier Ltd, 2018) Naik, P.; Keremane, K.S.; Elmorsy, M.R.; Su, R.; El-Shafei, A.; Vasudeva Adhikari, A.V.
    Herein, we report a comparative study of four interesting metal-free carbazole based organic dyes with different structural configurations, carrying electron deficient barbituric acid (C1-4), as effective co-sensitizers in DSSCs sensitized with NCSU-10 dye. The new entities comprise different structural architectures, viz. D-A (C1), D-?-A (C2), D-D-?-A (C3) and D-A-?-A (C4) configurations with same accepting/anchoring moiety. They consist of carbazole as donor scaffold linked to barbituric acid as an acceptor/anchoring unit via different ?-spacers. This paper describes the study of all the four co-sensitizers with regard to their structural, photophysical, electrochemical, theoretical and photovoltaic investigations. Also, it includes their structure-performance correlation study in detail. The devices co-sensitized with C1-4 displayed the superior photovoltaic performance when compared to NCSU-10 alone. The results ameliorate the role of efficient co-sensitizers to yield DSSC with improved performance. © 2018 Elsevier Ltd
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    Improvement in performance of N3 sensitized DSSCs with structurally simple aniline based organic co-sensitizers
    (Elsevier Ltd, 2018) Naik, P.; Abdellah, I.M.; Abdel-Shakour, M.; Su, R.; Keremane, K.S.; El-Shafei, A.; Vasudeva Adhikari, A.V.
    In this work, we report comprehensive photovoltaic investigation of four structurally simple D-A configured organic dyes, A1-4 as active co-sensitizers in DSSCs sensitized with well-known Ru (II) based N3 dye. These effective co-sensitizers (A1-4) comprise N,N-dimethylaniline ring as donor scaffold linked with electron withdrawing functionalities, viz. barbituric acid (A1), N,N-dimethyl barbituric acid (A2), thiobarbituric acid (A3), and N,N-diethyl thiobarbituric acid (A4) as acceptor/anchoring units. In the present study, for the first time we have demonstrated the profound role of various simple organic molecules carrying different heterocyclic anchoring units on the photovoltaic parameters of the N3 sensitized devices. Also, the effect of concentration of sensitizer/co-sensitizers on the device performance characteristics has been investigated in depth. From the results, it is evident that, the device fabricated using co-sensitizer A2 carrying N,N-dimethyl barbituric acid along with sensitizer N3 in all concentrations outperformed when compared to N3 alone or other co-sensitizers. Interestingly, the best photovoltaic performance was obtained for the co-sensitized device fabricated using 0.3 mM co-sensitizer A2 along with 0.2 mM of N3 sensitizer. It displayed PCE of 7.02% with JSC of 15.27 mA·cm?2, VOC of 0.671 V and FF of 68.47%. Thus, the observed results have thrown new light upon the device optimization to yield DSSCs with improved performance by the selection of matchable co-sensitizers at appropriate concentrations. © 2018 Elsevier Ltd
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    Asymmetric Dual Anchoring Sensitizers/Cosensitizers for Dye Sensitized Solar Cell Application: An Insight into Various Fundamental Processes inside the Cell
    (American Chemical Society service@acs.org, 2019) Kesavan, R.; Attia, F.; Su, R.; Anees, P.; El-Shafei, A.; Vasudeva Adhikari, A.V.
    To study the various fundamental processes occurring inside the dye sensitized solar cell (DSSC), we have fabricated devices employing newly synthesized diphenylamine-based organic dyes with A-D-?-A configuration, carrying four different anchoring groups, namely, cyanoacetic acid (DDC), rhodanine acetic acid (DDR), 4-hydrazinylbenzoic acid (DDH), and barbituric acid (DDB), as effective sensitizers/cosensitizers. In the present work, all the bianchoring dyes were subjected to photophysical, electrochemical, thermodynamic, photoelectrochemical, and theoretical studies. All of them displayed characteristic ?abs and ?emi in the range of 415-480 and 570-680 nm, respectively. Their optical and electrochemical band gaps were calculated to be in the order of 2.1 to 2.3 eV. The calculated driving forces for electron injection (?Ginj), recombination (?Ginj), and regeneration (?Greg) processes were found to be negative, showing the feasibility of these processes, while their DFT studies clearly indicated the directional flow of electrons within the dye in the cell. The devices with DDC as sensitizer displayed the highest conversion efficiency of 2.53%, whereas DDB exhibited the maximum of 7.69% when employed as a cosensitizer along with Ru (II) based HD-2 dye. Finally, EIS circuit fitting was carried out in order to obtain different interface resistance values to study the fundamental processes of energy conversion. © © 2019 American Chemical Society.
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    Simple thiophene-bridged D-?-A type chromophores for DSSCs: a comprehensive study of their sensitization and co-sensitization properties
    (Royal Society of Chemistry, 2020) Keremane, K.S.; Abdellah, I.M.; Naik, P.; El-Shafei, A.; Vasudeva Adhikari, A.V.
    Herein, we report the design and synthesis of four new thiophene-bridged D-?-A configured organic dyes T1-4 comprising different donors, ?-spacers and anchoring units, as potential sensitizers and co-sensitizers for DSSCs. The current work also highlights their structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies, including evaluation of their structure-property relationships. The optical results revealed that the dyes T1-4 display ?abs and ?emi in the range of 402-461 nm and 556-575 nm, respectively, with a bandgap in the order of 2.31-2.58 eV. Furthermore, the results showed that the dyes possess all the pre-requisites to act as sensitizers/co-sensitizers. Among the tested dyes, the device based on sensitizer T2 achieved the highest PCE compared to the other three dyes, under the standard conditions. Furthermore, their co-sensitized devices were fabricated by co-adsorbing them with the well-known Ru-based MH-12 sensitizer and interestingly the co-sensitizer T3 carrying an alkoxy group and a barbituric acid anchor displayed the highest PCE of 8.79%, which is much higher than that of MH-12 alone (8.18%). Conclusively, the study furnishes a deeper understanding of the intricacies involved in the structural modification of sensitizers/co-sensitizers in achieving an enhanced performance of the devices. This journal is © 2020 the Owner Societies.