Faculty Publications
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Item New cyanopyridine based conjugative polymers as blue emitters: Synthesis, photophysical, theoretical and electroluminescence studies(Elsevier B.V., 2018) Pilicode, N.; K M, N.; M N, S.; Vasudeva Adhikari, A.V.Herein, we report the design of three new blue light emitting conjugated polymers (Th-Py-1, Th-Py-2 and Th-Py-3), carrying cyanopyridine ring as a strong electron accepting unit and thiophene as well as phenylene vinylene scaffolds with different substituents, as electron donating moieties. The newly designed monomers/polymers were synthesized using well-known synthetic protocols such as cyclocondensation, O-alkylation, Suzuki cross coupling, Wittig and Knoevenagel reactions. They were well-characterized by spectral, thermal, photophysical, electrochemical and gel permeation chromatography (GPC) techniques. Further, they were subjected to theoretical studies using DFT simulations, performed at B3LYP/TZVP level using Turbomole 7.2 V software package. The new polymers were tested in PLED devices (ITO/PEDOT: PSS/Polymer/Al) as emissive materials. Optical studies revealed that, all the polymers displayed light absorption in the range of 377–397 nm and blue light emission in the order of 432–482 nm, respectively. Further, their band-gaps were calculated to be in the order of 2.55–2.64 eV using both optical and electrochemical data. Furthermore, the TGA study indicated that, they possess good thermal stability with onset decomposition temperature, greater than 300 ?C under nitrogen atmosphere. Interestingly, use of these polymers in new PLEDs as emissive layers, has shown improved performance when compared to previously reported polymers in similar type of devices. They show blue light emission with a low threshold voltage of 3.5–3.9 V, affirming an efficient electron injection in the diodes. © 2018 Elsevier B.V.Item An Efficient Aniline-Based Co-Sensitizer for High Performance N3-Sensitized Solar Cells(Wiley-Blackwell info@wiley.com, 2018) Naik, P.; Abdellah, I.M.; Abdel-Shakour, M.; Acharaya, M.; Pilicode, N.; El-Shafei, A.; Vasudeva Adhikari, A.V.In this work, we report a comprehensive photovoltaic investigation of a structurally simple Donor-Acceptor (D?A) configured organic dye, N,N-PABA as an active co-sensitizer in DSSCs sensitized with well-known Ru (II) based N3 dye. This effective co-sensitizer (N,N-PABA) comprises N,N-dimethylaniline system as a donor scaffold linked with 4-aminobenzoic acid as an electron withdrawing functionality. In the present study, we have demonstrated the profound effect of concentration of sensitizer, i. e. N3 based dye as well as co-sensitizer, i. e. N,N-PABA on the photovoltaic performance characteristics of solar cells. Interestingly, the best photovoltaic performance was obtained for the co-sensitized device fabricated using 0.2 mM of N,N-PABA along with 0.3 mM of N3 sensitizer, in presence of 20 mM of CDCA. It displayed power conversion efficiency (PCE) of 5.82% with JSC of 14.35 mA.cm?2, VOC of 0.626 V and FF of 64.85%. Here, the N,N-PABA effectively filled the absorption valley, avoided the dye aggregation and reduced the charge recombination in the co-sensitized devices. Thus, the results ameliorate the role of efficient co-sensitizers to yield DSSC with improved performance by the selection of a matchable co-sensitizer at an appropriate concentration. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimItem New blue light emitting cyanopyridine based conjugated polymers: From molecular engineering to PLED applications(Elsevier B.V., 2019) Pilicode, N.; K M, N.K.; Acharya, M.; Naik, P.; N, S.M.; Vasudeva Adhikari, A.V.In this work, we report the design of three new cyanopyridine scaffold based polymers, viz. TPy 1-3 as potential blue light emitters for PLED applications. The new polymer design comprise, a cyanopyridine core as an electron accepting entity, thiophene as an electron donating unit with different auxiliary donors, viz. phenylene (TPy 1 ), biphenyl (TPy 2 ), and fluorene (TPy 3 ), and have been synthesized, following standard synthetic protocols including Suzuki-cross coupling polymerization reaction. Further, in order to assess all the prerequisites to act as an active emitter, the polymers TPy 1-3, were subjected to structural, thermal, linear optical, electrochemical and computational studies. The results revealed that, all the polymers were thermally stable up to 300 ?C and their estimated optical band-gaps were found to be 2.59–2.80 eV. Finally, new polymer light emitting diode (PLED) were fabricated by employing the polymers TPy 1-3, as active emissive material with a configuration of ITO/PEDOT: PSS/Polymer/Al. Interestingly, all the fabricated devices, exhibited an intense blue electroluminescence at 12 V with low threshold voltages of 4.2–4.8 V, signifying an effective injection of electron in the device. © 2019 Elsevier B.V.Item New cyanopyridine based conjugated polymers carrying auxiliary electron donors: From molecular design to blue emissive PLEDs(Elsevier Ltd, 2020) Pilicode, N.; Naik, P.; K M, K.M.; Acharya, M.; Satyanarayan, M.N.; Vasudeva Adhikari, A.V.Three new D-A (Donor-Acceptor) configured conjugated polymers, i.e. PPy1-3, centered on strong electron accepting cyanopyridine scaffold carrying varied auxiliary donors, viz. phenylene (PPy1), biphenyl (PPy2), and fluorene (PPy3) were designed and synthesized as blue emitters for PLEDs. The new polymers were subjected to spectral, thermal, photophysical and electrochemical characterization. Also, computational studies (DFT) were performed on the repeating units of polymer using Turbomole 7.2 V software package at the B3LYP/TZVP hybrid levels. Further, their weight average molecular masses were found to be 38.8 kDa, 38.9 kDa and 57.7 kDa, respectively as determined by GPC technique. Furthermore, the new polymers PPy1-3, were shown to be stable thermally up to 308–374 °C. Evidently, they exhibited good photophysical behavior with their optical energy band gaps of 2.53–2.64 eV. Finally, the polymers PPy1-3 were employed as an active emissive layer in standard ITO/PEDOT:PSS/Polymer/Al configured PLEDs. Interestingly, at 12 V all the newly fabricated devices exhibit a stable blue characteristic electroluminescence with low threshold voltages of 3.40–5.20 V, confirming an efficient injection of electrons in the diodes. From the results, it is clear that, the polymers PPy1-3, can be considered as prospective blue light emitters for PLED application. © 2019 Elsevier LtdItem Synthesis, characterization and electroluminescence studies of cyanopyridine-based ?-conjugative polymers carrying benzo[: C] [1,2,5]thiadiazole and naphtho[1,2- c:5,6- c ?]bis([1,2,5]thiadiazole) units(Royal Society of Chemistry orders@rsc.org, 2020) Pilicode, N.; Naik, P.; Acharya, M.; Vasudeva Adhikari, A.V.Four new donor-acceptor type cyanopyridine-based conjugative polymers, i.e.TDPy1-4, carrying different electron-donating aromatic/heteroaromatic moieties in the backbone were synthesized from their respective co-monomers by using the Suzuki cross-coupling polycondensation protocol. These polymers were designed to possess good control of color emission and to have balanced charge injection, and transport properties. Their structures were confirmed by spectroscopic studies and their thermal stability was evaluated using the TGA technique. The photophysical, electrochemical and electroluminescence properties of these materials were established in order to assess their suitability for PLED applications. DFT-based computational studies were performed to verify and elucidate the above-said properties. Evidently, they demonstrate good green fluorescence with optical band gap (Eg) values of 2.14-2.27 eV. Finally, new PLEDs based on TDPy1-4 were fabricated with a structure of ITO/PEDOT:PSS/polymer/Al, wherein they are able to act as green light emitters with stable electroluminescence behaviors. © 2020 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Nicotinonitrile centered luminescent polymeric materials: Structural, optical, electrochemical, and theoretical investigations(John Wiley and Sons Inc, 2020) Pilicode, N.; Naik, P.; Vasudeva Adhikari, A.V.Herein, we describe the design, synthesis, and structural characterization of three new push-pull type conjugative polymers, that is, VPPy1-3 comprising strong electron-withdrawing N-heterocyclic nicotinonitrile scaffold coupled with electron-donating phenylene units through vinylene bridges, as promising candidates for optoelectronic applications. They were successfully synthesized from their respective co-monomers by simple polycondensation synthetic routes, viz. Knoevenagel and Wittig reactions. All the polymers were subjected to photophysical, electrochemical, thermal, and theoretical studies in order to ascertain their suitability in polymer light-emitting diode applications as blue emitters. Evidently, they are readily soluble in most of the organic solvents, enabling them easy solution-processable. These new polymers display strong blue photoluminescence at the peak in the range of 431 to 462 nm with a wide optical bandgap in the order of 2.55 to 2.63 eV. The obtained electrochemical data were employed to evaluate their HOMO/LUMOs. The density functional theory calculations generated useful information on their FMO, molecular geometries, and electronic properties. Also, the influence of their structural modification on the above-said properties was discussed in detail to reveal the structure-property relationship. Conclusively, these results illustrate the great prospective of this class of polymeric materials for the application in solution-processable blue LEDs. © 2020 Society of Plastics EngineersItem New cyanopyridine-based ?-conjugative poly(azomethine)s: Synthesis, characterization and electroluminescence studies(John Wiley and Sons Ltd, 2021) Pilicode, N.; Naik, P.; K M, K.M.; Acharya, M.; Satyanarayan, M.N.; Vasudeva Adhikari, A.V.Four new Schiff-base type conjugative polymers (CPs), that is, Py1-4 carrying a strong electron-withdrawing cyanopyridine scaffold coupled with different electron-donating aromatic/heteroaromatic moieties were synthesized from their respective co-monomers by simple poly-condensation route. They were subjected to structural, thermal, photophysical, and electrochemical characterizations and theoretical investigations in order to identify their suitability in polymer light-emitting diode (PLED) application. All these polymers showed good film-forming ability and exhibited favorable photophysical behaviors with an optical bandgap in the order of 2.54-2.68 eV. Further, their electrochemical data were used to evaluate highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels. Finally, Py1-4 were successfully employed as blue-light emitter in the construction of new ITO/PEDOT:PSS/ Py1-4/Al configured light-emitting diodes (LED), and the fabricated devices demonstrated stable blue electroluminescence behavior endorsing an effective electrons injection in the PLEDs. © 2020 John Wiley & Sons LtdItem Synthesis, optical, electrochemical, and computational investigation of new cyanopyridine-centered organic dyads(Elsevier B.V., 2023) Naik, P.; Pilicode, N.; Keremane, K.S.; Acharya, M.; Vasudeva Adhikari, A.V.Herein we report the molecular design, synthesis, and inclusive investigation of four novel di-anchored symmetric dyes (CP1-4) centered on electron deficient cyanopyridine scaffold as possible photosensitizers for DSSC application. These new chromogens (CP1-4) comprise a powerful electron-withdrawing cyanopyridine moiety linked with additional electron attracting functionalities such as cyanoacetic acid (CP1), 3-(carboxymethyl) rhodanine (CP2), 2,4,6-pyrimidinetrione (CP3), and 2,6-dihydroxy-2-mercaptopyrimidine (CP4), as effective acceptor/anchoring units via biphenyl donor units. Their in-depth optical and electrochemical behaviour were investigated to assess their suitability as photosensitizers. Further, the molecular modeling calculations were undertaken to understand their ground state properties and energy level potentials. The comprehensive studies revealed that they own all the requisites to performance as a potential photosensitizer for DSSC application. © 2023 Elsevier B.V.