Browsing by Author "Keremane, K.S."

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A Molecular-Level Exploration of Dopant-Free Pyrazine-Derived Hole Transport Materials: Investigation of Interfacial Interaction in Perovskite Photovoltaics
(John Wiley and Sons Inc, 2025) Sheshachala, A.; Keremane, K.S.; Bhat, V.G.; Karunakar Shankar, S.; Asuo, I.M.; Doumon, N.Y.; Poudel, B.; Udayakumar, U.
The development of innovative core structures and peripheral groups for organic hole-transporting materials (HTMs) continues to be a focal point in enhancing the performance of perovskite solar cells (PVSCs). This study reports the design and synthesis of dopant-free pyrazine-based HTMs. PS1 features a D–A–D type structure with pyrazine as the acceptor and 4,4?-dimethoxy triphenylamine (4,4?-OMe-TPA) as the donor, while PS2 adopts a D–?–A–?–D configuration with an additional thiophene unit as ?-spacer along with 4,4?-OMe-TPA as donor. Both compounds are synthesized through a simple two-step synthetic procedure. These HTMs are subjected to structural, photophysical, electrochemical, theoretical, and photoelectrochemical studies with an emphasis on evaluation of structure–property relationships. Theoretical studies are conducted to explore the electronic distribution, optimized molecular structure, and frontier molecular orbitals. Their performance in PVSCs is systematically evaluated without adding dopants. PS2 exhibits superior photoluminescence quenching compared to PS1, indicating more efficient charge transfer from the perovskite layer. Notably, PS2 achieves a power conversion efficiency (PCE) of 11.9%, surpassing the performance of PS1 (PCE of 10.15%). These findings highlight the potential of adjusting the electron-deficient core and ?-bridge units as an effective strategy to optimize the properties of HTMs and improve their performance in PVSC applications. © 2025 Wiley-VCH GmbH.
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.
Biomass-Derived Reaction Media Towards the Iodination of Anilines Under the Catalytic Influence of Magnetically Separable Pd@rGO-CuFe2O4
(Bentham Science Publishers, 2025) Reetu, R.; Teli, Y.A.; Patel, M.J.; Keremane, K.S.; Dutta, S.; Malakar, C.C.; Almeer, R.
Investigation of a biomass-derived solvent, such as ?-valerolactone (GVL), for the iodination of anilines was devised. The process is accomplished under the catalytic influence of a magnetically separable Pd@rGO-CuFe2O4catalyst (with 0.00047 mol% Pd loading) at 25°C. The catalyst is recovered from the reaction medium using an external magnet and recycled for five consecutive reaction cycles with very minor catalyst leaching. The developed strategy has been thoroughly studied over a series of starting materials to obtain the iodoaniline derivatives, and the desired products were obtained effectively in yields up to 91% with high regioselectivity. A plausible reaction mechanism was proposed based on previous findings. This method has been extended to gram-scale synthesis with a 76% yield of the desired product. © 2025 Bentham Science Publishers
Carbazole based organic dyes as effective photosensitizers: A comprehensive analysis of their structure-property relationships
(John Wiley and Sons Inc, 2022) Naik, P.; Keremane, K.S.; Elmorsy, M.R.; El-Shafei, A.; Vasudeva Adhikari, A.V.
The present work describes the effect of structural modification of carbazole-based photosensitizers carrying carboxylic acid as a common anchoring functionality, on the photovoltaic parameters of newly fabricated DSSCs. In this study, we have selected our previously reported three carbazole-based derivatives, viz. S1-3 having different structural designs, that is, D-π-A (S1), D-D-π-A (S2), and A-π-D-π-A (S3) with different donor units and π-spacers, but an identical cyanoacetic acid anchoring unit. We have evaluated their optical, electrochemical, and photovoltaic behaviors in order to explore their structure-property relationships. Also, the theoretical investigations were performed to obtain a deeper understanding of their HOMO-LUMO levels, charge distribution in FMOs, directional flow of electrons within the push-pull type sensitizers, and optical behavior. Finally, the DSSCs were constructed by employing these dyes as sensitizers without any co-absorbents and the performance of the devices was evaluated by using illuminated current-voltage characteristics. Among the tested dyes, di-anchoring S3 exhibited improved PCE of 3.77 % due to its strong adsorption on the TiO2 surface that resulted in superior VOC of the cell. While the S2 containing electron-releasing anisole as an auxiliary donor exhibited better JSC value leading to the optimum PCE of 3.73 % which is comparable to that of S3. Obviously, these results validate the role of the π-spacer and additional donor of the sensitizers on the overall performance of the DSSCs. © 2021 The Authors. Electrochemical Science Advances published by Wiley-VCH GmbH.
Dopant-free hydrophobic fluorene-based hole transport materials: impact of methoxy-substituted triphenylamine and carbazole peripheral groups on the performance of perovskite solar cells
(Royal Society of Chemistry, 2025) Bhat, V.G.; Keremane, K.S.; Subramanya, K.S.; Archana, S.; Hegde, A.; Asuo, I.M.; Poudel, B.; Udayakumar, U.
Hole-transporting materials (HTMs) are crucial for charge separation in perovskite solar cells (PVSCs). Besides possessing suitable HOMO/LUMO energies, HTMs should ideally be hydrophobic to protect the perovskites from atmospheric moisture to enhance device stability. We designed two fluorene-core D-?-D-type organic HTMs (V1 and V2), consisting of either 4,4?-methoxy triphenylamine (V1) or N-phenyl-3,6-methoxy carbazole (V2) as the peripheral donor moiety. Optoelectronic characterization and density functional theory calculations confirmed the intramolecular charge transfer within these new HTMs. UPS and REELS analyses revealed favorable HOMO-LUMO energy level alignment of V1 and V2 with the work functions of MAPbI3 and gold electrode for effective charge extraction. TRPL and transient absorption studies commendably explained better quenching of perovskite's luminescence by V1 over V2, suggesting a better interfacial contact of V1 with the perovskite layer. Accordingly, the PVSCs with V1 and V2 as HTMs in an architecture ITO/SnO2/MAPbI3/HTM(V1 or V2)/Au demonstrated power conversion efficiency (PCE) of 14.05% and 12.73% respectively. Also, the device with V1 retains 75% of its initial efficiency for more than 480 hours. The contact angle measurements revealed the strong hydrophobicity of both alkylated fluorene molecules (V1 and V2), and impedance spectroscopy measurements further revealed higher Rrec values for these HTMs, indicating improved charge transport and reduced recombination losses. These findings demonstrate the potential of the newly developed hydrophobic fluorene-based HTMs for achieving long-lasting performance in PVSCs. © 2025 The Royal Society of Chemistry.
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.
Highly efficient carbazole based co-sensitizers carrying electron deficient barbituric acid for NCSU-10 sensitized DSSCs
(2018) Naik, P.; Keremane, K.S.; Elmorsy, M.R.; Su, R.; El-Shafei, A.; 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
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
Improvement in performance of N3 sensitized DSSCs with structurally simple aniline based organic co-sensitizers
(2018) Naik, P.; Abdellah, I.M.; Abdel-Shakour, M.; Su, R.; Keremane, K.S.; El-Shafei, A.; Vasudeva, Adhikari, A.
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
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
Improving the Performance of Carbon-Based Perovskite Solar Modules (70 cm2) by Incorporating Cesium Halide in Mesoporous TiO2
(American Chemical Society, 2021) Keremane, K.S.; Prathapani, S.; Haur, L.J.; Bruno, A.; Priyadarshi, A.; Vasudeva Adhikari, A.V.; Mhaisalkar, S.G.
We present the fabrication of highly efficient large-area carbon-based perovskite solar cells (C-PSCs) using CsX (X = Cl, Br, and I)-modified mesoporous (mp) TiO2 beads of 40 nm size as an electron transport material. Here, triple-layered scaffolds made of cesium halide-modified TiO2 exhibit efficient charge extraction as confirmed by enhanced photoluminescence quenching and inhibit the UV-activated degradation processes of perovskite, leading to an enhanced operational stability. Among the three cesium halide modifications, devices containing CsBr-modified TiO2 showed the highest short-circuit current density, yielding a photoconversion efficiency (PCE) of 12.59% of the device, with 0.7 cm2 active area and 11.55% for a large-area module (70 cm2). These devices are stable in an ambient atmosphere (25 °C, 65-70% RH) over 2700 h as well as at a high temperature (85 °C) over 750 h with virtually no hysteresis. © 2021 American Chemical Society. All rights reserved.
New Carbazole-Based Sensitizers for p-Type DSSCs: Impact of the Position of Acceptor Units on Device Performance
(American Chemical Society, 2022) Keremane, K.S.; Pellegrin, Y.; Planchat, A.; Jacquemin, D.; Odobel, F.; Vasudeva Adhikari, A.V.
We report the design, synthesis, and characterization of two new carbazole-based organic dyes PC1-2as potential sensitizers for NiO-based p-type dye-sensitized solar cells (p-DSSCs). The D-A-π-A' configured PC1dye comprises a thienyl unit as a π-spacer and a malononitrile as an end-capping acceptor unit, whereas in PC2the cyanovinylene group serves as an acceptor unit and a thienyl group acts as a donor unit in a D-A-D configuration. These molecules achieved excellent solubility due to their long-branched alkyl chains. The current work encompasses their structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies, establishing structure-property relationships. PC1-2exhibit λabsand λemiin the range of 389-404 and 448-515 nm, respectively, with a band gap in the range of 2.88-2.92 eV. Electrochemical studies confirm the feasibility of electron injection, regeneration, and recombination. The introduction of an additional electron-withdrawing group (cyanovinylene group) on the dye PC1skeleton endows it with a higher dye loading capacity, high hole injection, and a strengthened intramolecular charge transfer (ICT) effect, resulting in a redshifted ICT absorption with a higher molar extinction coefficient. Among the two new dyes, the device based on PC1achieved the highest power conversion efficiency (PCE) of 0.027% with a short-circuit current density (JSC) of 1.29 mA·cm-2, open-circuit voltage (VOC) of 67 mV, and fill factor (FF) of 31%, whereas the device with dye PC2performed less efficiently (PCE: 0.018%, JSC: 0.92 mA·cm-2, VOC: 68 mV, and FF: 30%). Conclusively, the study provides insights into the intricacies involved in the structural modification of carbazole-based p-type dyads for the development of highly efficient DSSCs. © 2022 American Chemical Society. All rights reserved.
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.
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.
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.
Simple 3,6-disubstituted Carbazoles as Potential Hole Transport Materials: Photophysical, Electrochemical and Theoretical Studies
(Blackwell Publishing Inc., 2021) Keremane, K.S.; Rao, R.; Vasudeva Adhikari, A.V.
Developing effective and low-cost organic hole-transporting materials (HTMs) is crucial for the construction of high-performance perovskite solar cells (PSCs) and to promote their production in commercial ventures. In this context, we herein report the molecular design, synthesis and characterization of two novel D-A-D-A-D architectured 9-(2-ethylhexyl)-9H-carbazoles, connecting the mono/dimethoxyphenyl substituted cyanovinylene sidearms symmetrically at 3rd and 6th positions of the carbazole heterocycle (CZ1-2), as potential hole-transporting materials (HTMs). The current work highlights their structural, photophysical, thermal, electrochemical and theoretical investigations, including their structure-property correlation studies. Evidently, the optical studies showcased their excellent fluorescence ability due to their push–pull natured structure with extended ?-conjugation. Further, in-depth solvatochromic studies demonstrated their intramolecular charge-transfer (ICT)-dominated optoelectronic behavior, supported by various correlation studies. Also, the optical results revealed that CZ1 and CZ2 display ?absand ?emi in the order of 410–430 nm and 530–560 nm, respectively, with a bandgap in the range of 2.5–2.6 eV. Finally, their quantum chemical simulations have provided an insight into the predictions of their structural, molecular, electronic and optical parameters. Conclusively, the study furnishes a deeper understanding of the intricacies involved in the structural modification of carbazole-based HTMs for achieving better performance. © 2020 American Society for Photobiology
Simple carbazole derivatives with mono/dimethoxyphenylacrylonitrile substituents as hole-transporting materials: Performance studies in hybrid perovskite solar cells
(John Wiley and Sons Inc, 2021) Keremane, K.S.; Vasudeva Adhikari, A.V.
Herein, we report the development of two new low-cost 9-(2-ethylhexyl)-9H-carbazoles carrying the mono/dimethoxyphenyl substituted cyanovinylene units symmetrically at 3- and 6-positions of the carbazole core (CZ1-2), as potential hole-transporting materials (HTMs) for perovskite solar cell (PSC) application. The current work highlights their structural, photophysical, electrochemical, theoretical, and photoelectrochemical studies, including evaluation of their structure-property relationships. Evidently, the optical studies showcased their excellent fluorescence ability due to their push-pull natured structure; their ?abs and ?emi values were found to be in the order of 410–430 nm and 530–560 nm, respectively, with a bandgap in the range of 2.5–2.6 eV. Further, their theoretical studies, performed by using the DFT simulations clearly revealed in-depth information on their molecular geometries, FMO, and electronic properties. Finally, new PSCs were fabricated successfully by employing CZ1-2 as HTMs to evaluate their photovoltaic performances. Their results indicated that the device with CZ1 displayed enhanced PCE of 2.55% (JSC= 7.85 mA/cm2, VOC= 0.79 V and FF = 40%) than the cell with CZ2 (PCE = 1.71%, JSC= 8.15 mA/cm2, VOC = 0.4 V, FF = 49%) and the obtained data are well comparable with reference, Sipro-OMeTAD (PCE = 4.76%, JSC= 12.27 mA/cm2, VOC = 0.84 V, FF = 45%). Conclusively, the study furnishes a deeper understanding of the intricacies involved in the structural modification of in low-cost HTM in achieving an enhanced performance of the devices. © 2021 The Authors. Electrochemical Science Advances published by Wiley-VCH GmbH.
Simple thiophene based organic dyes as active photosensitizers for dssc application: From molecular design to structure property relationship
(Sumy State University larysa.odnodvorets@gmail.com, 2020) Keremane, K.S.; Naik, P.; Vasudeva Adhikari, A.V.
The main objective of our present investigation includes the design synthesis and characterization of two novel D--A configured thiophene based dyes C1-2, carrying two different anchors and the same donor system. In the new design, a simple O-alkylated phenyl group as a donor scaffold, cyanovinylene and thiophene group serve as a-spacer, while cyanoacetic acid, barbituric acid units function as electron acceptor/ anchoring units. The newly synthesized compounds were characterized by FTIR, NMR spectroscopic techniques including the elemental analysis. Further, their optical properties were investigated by using UV-visible, fluorescence spectrophotometer. In addition, the Density functional theory (DFT) calculations were performed to get their electron distribution in FMO levels. In order to investigate their photovoltaic characteristics, the synthesized dyes were employed as sensitizers towards the fabrication of DSSC's. The device fabricated with dye C1 displayed better PCE of 1.2 % with JSC of 3.64 mA·cm-2, VOC of 0.50 V and FF of 65 % than other dye C2. These experimental results provide a better understanding and deeper insight into the intricacies involved in the design of superior sensitizers to further improve the performance of DSSCs. © 2020 Sumy State University.
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.
Solvent selection for highly reproducible carbon-based mixed-cation hybrid lead halide perovskite solar cells via adduct approach
(2020) Keremane, K.S.; Prathapani, S.; Haur, L.J.; Bahulayan, D.; Adhikari, A.V.; Priyadarshi, A.; Dr.; Mhaisalkar, S.G.; Prof.
The major problem identified in carbon-based mixed cation perovskite solar cells (PSCs) is the selection of a suitable solvent for single-step solution-processed perovskite deposition in order to promote their scalable production. Herein we report a detailed study on the selection of appropriate solvent for the one-step deposition of cesium-formamidinium lead iodide (Cs0.1FA0.9PbI3) perovskite via Lewis acid-base adduct approach for fully printable mesoporous PSCs with mesoporous TiO2/ZrO2/C architecture. Highly reproducible Cs0.1FA0.9PbI3 solar cells were fabricated via adducts of PbI2 with eco-friendly dimethyl sulfoxide (DMSO). The best cells fabricated with the above approach yielded a photoconversion efficiency (PCE) of 12.33% for a small area device (active area: 0.09 cm2) and 10.1% for a large area device (active area 0.7cm2). The average power conversion efficiency for 62 PSCs was found to be 10.5% under an AM 1.5G illumination. Finally, the mixed cation perovskite in carbon architecture using the Lewis acid-base adduct approach is remarkably stable, with less than 1% change from the initial PCE after 1800h of storage under dark ambient conditions (25 C, 60 70% RH). 2020 International Solar Energy Society