I am a research scholar at IISER Thiruvananthapuram, India.
I am a researcher from India. I have Physics background. at present, I am concentrating on the fabrication and characterization of different organic solar cells. I am also interested in synthesizing various metal nanoparticles and incorporating them into organic solar cells (plasmonic solar cell) and study its plasmonic effects.
Solar energy to meet our daily energy needs.
To meet our growing energy needs, the conventional energy resources are insufficient. Renewable energy resources like solar energy are being used as an alternative source. But the high cost of Si (inorganic) solar cells prevents its wide usage. In this scenario, organic solar cells, which are low cost and flexible, can be used to convert solar energy into useful electricity. Researchers all over the world are working on such organic systems to improve the efficiency and performance. Organic solar cells have the advantage of being fabricated using roll-to-roll mechanism and printing technology. This enables the production of organic solar cells in large quantity.
Abstract: Nanocrystal/polymer solid solar cells have the advantages of low-cost, simple process, and flexible manufacture. In this work, ternary solid solar cells based on FeS2 and PbS nanocrystals exhibited photovoltaic conversion efficiency of 3.0% and 3.1%, respectively. As a kind of semiconductor with optical absorption in the visible and near-infrared regions, FeS2 nanocrystals matched well with the solar radiation spectrum. Furthermore, PbS Nanocrystals could increase the number of electrons, due to its multiple exciton effect. Additionally, the FeS2 nanocrystals solar cells showed high stability, with 83.3% of its initial efficiency remained after 15 weeks of exposure in air, and kept good stable performance at 20–80 °C. The photovoltaic conversion efficiency fluctuation magnitudes were also found to be smaller than quantum-dot sensitized solar cell under the same conditions.
Pub.: 23 Apr '16, Pinned: 01 Jul '17
Abstract: Publication date: March 2017 Source:Solar Energy Materials and Solar Cells, Volume 161 Author(s): Ramasamy Ganesamoorthy, Govindasamy Sathiyan, Pachagounder Sakthivel Bulk hetro-junction organic solar cells (BHJ-OSCs) which made by coating the blend of highly electron rich, poly-3-hexylthiophene (P3HT) as a donor and extremely electron deficient, soluble C60 derivative, [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as an acceptor between the high work function positive electrode, ITO and low work function metal negative electrode Al, showed exciting results than the bilayer counterpart in the last two decades, thus the scientific circle and solar cell manufacturing groups are focusing on this treasured field. Fullerene derivative based BHJ-OSCs showed astonishing efficiencies due the high donor-acceptor (D-A) interface, high open-circuit voltage (Voc), easy processing, and thermal stability. Hence, the design of the fullerene derivative plays a vital role in the efficiency of the OSCs. Numerous papers were published on the PC61/71BM and various functionally modified fullerene acceptors in the past several years with higher efficiency, higher LUMO level, and improved solubility. The symmetrical structure of PC61BM showed high aggregation properties, insufficient absorption in the visible region, but unsymmetrical PC71BM had a good optical absorption in the visible region, hence it was the most desirable choice for best performing solar cells. From the comparison, it was clear that the modification in the PC61/71BM core with aryl group, alkyl chain length, and end group modification didn’t show any significant difference in the PCE with the P3HT polymer donor in BHJ-OSCs device structure. Fullerenes multi-adducts performed better than the PC61/71BM due to the development in the Voc. In multi-functionalization, mainly bis-functionalization showed better performance than mono-adduct. C60 and C70 based hetro bis-adducts namely, C60(CH2)(Ind), and OQMF70 showed the highest PCE of 5.90%, and 6.61% respectively, which was comparable with the indene based bis-adducts. Commonly, tris-adduct fullerenes showed the lowest PCE due to the isomer effect and electron trapping, but OQBMF was a hetro tris-adduct of C60-methanofullerenes, which showed a excellent PCE of 6.43% due to improved Voc. Similarly, indene substituted C60 and C70 fullerenes based bis-adducts showed supreme PCE, of 6.5% (IC60BA) and ~6.7% (IC70BA) respectively, peak PCE was attributed to the high electron donating indene group, which enhanced the LUMO level due to the shrinkage in the π-system. The dihydronapthyl based fullerene bis-adduct derivatives such as, NC60BA, and NC70BA showed the best performance of 5.37%, and 5.95% respectively, than the mono-adduct. Even though abundant fulleropyrrolidines were reported, the performance of the fulleropyrrolidines based device was very deprived than the PC61/71BM based devices. Though the OSCs are comparatively efficient for commercial application due the insufficient efficiency and lower environmental stability factors controls the early arrival to the market. Therefore, it is essential to go through the recent fullerene derivatives based literatures, including mono-, bis-, tris- and multi-adducts of various methanofullerene derivative, indene based fullerene derivatives, dihydronaptyl substituted fullerenes, fulleropyrolidines, 1,2 and 1,4-adducts and fullerene derivatives for OSCs applications. In this regard, we discussed the present development in fullerene derivative and summarized the efficient fullerene derivatives for the BHJ-OSCs application and suggest a possible scenario for the future development in the fullerene cage. Graphical abstract
Pub.: 05 Dec '16, Pinned: 01 Jul '17
Abstract: Modifying the electron-withdrawing capability in donor–acceptor conjugated copolymers allows designing new polymers with better optical properties. These materials have been successfully applied in bulk heterojunction solar cell devices, and recently a great progress in the enhancement of power conversion efficiencies (PCE) has been achieved. In 2006 Scharber proposed a design rule to obtain PCE values over 10%, optimizing the orbital energy levels of the donor material. The present work proposes a methodology capable to predict theoretically the best efficiencies imparted by a group of 65 conjugated monomeric units selected from the literature, generating 2080 possible DA combinations. The geometries, frontier levels and optical properties were estimated by DFT methods. Based on the results, it was possible to predict the PCE of the most promising 22 copolymers. The results of the calculations indicated that several polymers investigated showed the predicted PCE between 9% and 10%. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017
Pub.: 08 Apr '17, Pinned: 01 Jul '17
Abstract: The nanoparticles Au/TiO2 embedded system plays a very important role in the plasmonic solar cell. Recently the scientists have focused their research both on the theoretical and technological problems. One of research orientations is focused on optimizing the characterizations of Au/TiO2 nanoparticles (NPs) for increasing efficiency of the plasmonic solar cell. This paper outlines the synthesis methods and some technological developments for preparation of the Au(10 %)/TiO2 and Au(40 %)/TiO2 solutions in the presence of polyvinylpyrrolidone (PVP) with different reaction rates of sodium borohydride adding into chemical reaction to control the Au NPs sizes, densities and dispersion of Au NPs being in Au/TiO2 NPs solution aiming to make the suitable Au/TiO2 thin film for application in plasmonic solar cell. The morphological, structural, absorption spectra of the Au/TiO2 NPs solutions in the presence of PVP and without PVP are investigated by the HRTEM, EDX, XRD and UV–Vis spectroscopy techniques. Depending on the technological conditions, in presence of PVP, the synthesized Au NPs being in Au/TiO2 solutions have their sizes are in range of 3–4 nm and of 8–10 nm with uniformly dispersed for the cases of slow reaction rate, and fast reaction rate, respectively, meanwhile the results of Au NPs synthesized without PVP which has different Au sizes, not uniformly dispersed. Based on experiment results the role and effects of PVP on controllable Au sizes, NPs densities and on the enhancement of the absorption spectra from peaks of 600 nm to the violet range are investigated and discussed.
Pub.: 04 Jul '16, Pinned: 01 Jul '17
Abstract: Flexible and crystallized indium-tin oxide (ITO) thin films were successfully obtained on plastic polyethylene terephthalate (PET) films with monolayered graphene as a platform. The highly crystalline ITO (c-ITO) was first fabricated on a rigid substrate of graphene on copper foil and it was subsequently transferred onto a PET substrate by a well-established technique. Despite the plasma damage during ITO deposition, the graphene layer effectively acted as a Cu-diffusion barrier. The c-ITO/graphene/PET electrode with the 60-nm-thick ITO exhibited a reasonable sheet resistance of ~45 Ω sq(-1) and a transmittance of ~92% at a wavelength of 550 nm. The c-ITO on the monolayered graphene support showed significant enhancement in flexibility compared with the ITO/PET film without graphene because the atomically controlled monolayered graphene acted as a mechanically robust support. The prepared flexible transparent c-ITO/graphene/PET electrode was applied as the anode in a bulk heterojunction polymer solar cell (PSC) to evaluate its performance, which was comparable with that of the commonly used c-ITO/glass electrode. These results represent important progress in the fabrication of flexible transparent electrodes for future optoelectronics applications.
Pub.: 11 Jun '17, Pinned: 01 Jul '17