Jitender Gaur

Diacetylene bridged triphenylamines as hole transport materials for solid state dye sensitized solar cells

We have synthesized and characterized a series of triphenylamine-based hole-transport materials (HTMs), and studied their function in solid-state dye sensitized solar cells (ss-DSSCs). By increasing the electron-donating strength of functional groups (–H < –Me < –SMe < –OMe) we have systematically shifted the oxidation potential and ensuing photocurrent generation and open-circuit voltage of the solar cells. Correlating the electronic properties of the HTM to the device operation highlights a significant energy offset required between the Dye – HTM highest occupied molecular orbital (HOMO) energy levels. From this study, it is apparent that precise control and tuning of the oxidation potential is a necessity, and usually not achieved with most HTMs developed to date for ss-DSSCs. To significantly increase the efficiency of solid-state DSSCs understanding these properties, and implementing dye-HTM combinations to minimize the required HOMO offset is of central importance.

Potential Antioxidant Anthraquinones Isolated from Rheum emodi Showing Nematicidal Activity against Meloidogyne incognita

Antioxidant and nematicidal properties were evaluated for R. emodi extractives which are extracted by standardizing and adopting accelerated solvent extraction (ASE) method along with traditional Soxhlet extraction. The extracted material was separated using flash chromatography and the separation conditions and solvents were standardized for the extracted plant constituents. The purity was detected by using analytical reverse phase high pressure liquid chromatography (HPLC). LC-MS/MS detection in the direct infusion mode of the isolated, purified products afforded four anthraquinones, characterized by their infrared spectra (IR) and 1H spectra as chrysophanol, physcion, emodin, and aloe-emodin. Five antraquinone glucoside derivatives and piceatannol-3-O-β-d-glucopyranoside have also been detected from the extracted product. During in vitro evaluation the antioxidant potential of methanolic crude extract (CE1) was the highest, followed by ethyl acetate crude extract (CE2) and chloroform extract (CE3) in DPPH radical scavenging activity. The CE1 also demonstrated outstanding nematicidal activity as compared with other extracts, pure anthraquinones, and even positive control azadirachtin. The study conclusively demonstrated the antioxidant potential of R. emodi extracts and also its ability in extenuating the Meloidogyne incognita (root-knot nematode). The bioassay results can be extrapolated to actual field condition and clinical studies.

Interaction studies of carbon nanomaterials and plasma activated carbon nanomaterials solution with telomere binding protein

Most cancer cells have telomerase activity because they can express the human telomerase reverse transcriptase (hTERT) gene. Therefore, the inhibition of the hTERT expression can play an important role in controlling cancer cell proliferation. Our current study aims to inhibit hTERT expression. For this, we synthesized graphene oxide (GO) and a functionalized multiwall carbon nanotube (f-MWCNT), latter treated them with cold atmospheric pressure plasma for further analysis of the hTERT expression. The inhibition of hTERT expression by GO, f-MWCNT, plasma activated GO solution (PGOS), and plasma activated f-MWCNT solution (PCNTS), was studied using two lung cancer cell lines, A549 and H460. The hTERT experimental results revealed that GO and PGOS sufficiently decreased the hTERT concentration, while f-MWCNT and PCNTS were unable to inhibit the hTERT concentration. Therefore, to understand the inhibition mechanism of hTERT, we studied the binding properties of GO and PGOS with telomere binding protein (AtTRB2). The interaction studies were carried out using circular dichroism, fluorescence, 1H-15N NMR spectroscopy, and size-exclusion chromatography (SEC) binding assay. We also used docking simulation to have an better understanding of the interactions between GO nanosheets and AtTRB2 protein. Our results may provide new insights that can benefit in biomedical treatments.

In-situ Growth of CdS Nanorods in PTB7 by Solvothermal Process for Hybrid Organic Inorganic Solar Cell applications

We demonstrate a high yielding, green approach using solvothermal, in situ growth of CdS nanorods (NRs) in a low band gap polymer, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl]] (PTB7). The use of chloroaniline dithiocarbamate and chloroaniline as ligands to functionalize the Cd (II) ions provides a new path for solubilization of Cd (II) complex in the chlorobenzene solvent. It removes use of volatile and hazardous chemicals such as pyridine as ligand which are conventionally used to enhance solubility of such complexes. It is the first example of solvothermal process used for in situ growth of CdS NRs in a polymer matrix. This nanocomposite is used to fabricate hybrid-organic–inorganic-solar cells (HOISC) as donor–acceptor combination in the bulk hetrojunction (BHJ) geometry. The incorporation of CdS NRs shows significant decrease in the band gap of PTB7 from 1.71 eV to 1.59 eV and the photoluminescence (PL) studies show significant quenching in the PL of PTB7 by the addition of CdS NRs. This suggests that the PTB7:CdS NRs is a potential nanocomposite for the bulk heterojunction active layer in the HOISCs. The HOISCs fabricated using the PTB7:CdS as donor–acceptor combination give power conversion efficiency of the order of 1.16 %. This work has implication in the development of green economical and efficient HOISC by using highly controlled synthetic process.

Sustainable Organic Polymer Solar Cells Using TiO2 Derived From Automobile Paint Sludge

We demonstrate green synthesis of TiO2 nanoparticles (Nps) derived from automobile paint sludge (APG) and its application in the development of sustainable and solution processable polymer solar cells (PSCs). The APG contains TiO2 > 35 % of its weight with several surfactants, organic polymers and ~ 2 to 10 % inorganic matter depending on the type of paints used. The TiO2 is generally present as micro sized particles in the APG which on hydrothermal treatment transform into nano sized particles. These organic matter is thermally extracted by a specially designed reaction vessel, where as the inorganic impurities are removed by repeated washing with dilute acids and bases. The TiO2 Nps are characterized by SEM imaging, EDX analysis, powder XRD, TG/DTA and FTIR, spectroscopy techniques. The TiO2 Nps are re-suspended in methanol for application in PSCs as an efficient electron transport layer. The TiO2 layer was spin coated on bulk hetero junction active layer of low band gap donor polymers P3HT with PCBM as electron acceptor. The performance of the TiO2 Nps is analyzed by fabricating devices in ITO/PEDOT:PSS/active layer/TiO2/Al configuration. The present work has implication for ultra low cost and sustainable PSCs with advantage of recycling of a highly hazardous industrial waste.

Charge Transport Studies in Pure and CdS Doped PBDTTPD:CdS Nanocomposite for Solar Cell Application

The recent trends in organic photovoltaic is towards the development of hybrid solar cells using the active absorption layer of a nancomposite layer having conjugated polymer incorporated with inorganic quantum dots, nanorods, nanoparticles, etc. The dispersion of nanomaterials in polymer matrix leads to inadequate charge transfer, agglomeration etc., which is a hindrance towards achieving high efficiency in the hybrid solar cells. On the other hand if nanomaterials are grown in situ into polymer matrix, it may enable to overcome the above disadvantage. Keeping this in view, we have synthesized a nanocomposite of PBDTTPD:CdS by in situ growth of CdS nanorods into polymer matrix. The charge transport mechanism was studied and the nanocomposite showed improvement in charge carrier mobility over the pure polymer which has been attributed to improvement in inter-chain charge transport by the presence of inorganic nanocrystals in polymer matrix.

Synthetic Strategies for Free & Stable N-Heterocyclic Carbenes and Their Precursors

Recently, chemical cross coupling reactions have emerged as a powerful tool in the hands of synthetic organic chemist to synthesize complicated organic scaffolds like drugs, natural products, optical devices and industrially impor- tant materials. Stable N-Heterocyclic Carbene (NHC) acts as an important catalyst system in various cross coupling reac- tions. This review describes various strategies used for the synthesis of free and stable NHCs. Historical developments made in the propagation of the idea of free and stable carbene have also keenly been illustrated in the introduction of this