Jaykrushna Das

Bio: Jaykrushna Das is an academic researcher from Weizmann Institute of Science. The author has contributed to research in topics: Perovskite (structure) & Fourier transform infrared spectroscopy. The author has an hindex of 6, co-authored 8 publications receiving 332 citations. Previous affiliations of Jaykrushna Das include Indian Institute of Technology Bombay & Tata Institute of Fundamental Research.

Dye Sensitized Solar Cells: A Review

Abstract: The development of dye sensitized solar cells (DSSCs), which have derived inspiration from photosynthesis, has opened up exciting new possibilities and paradigms for producing solar photovoltaics possibly at lower cost. The dye-sensitized solar cells with moderate power conversion (∼10%) efficiencies can be manufactured under regular lab conditions without needing clean rooms or very specialized facilities. The entire processing need not involve even a single vapour deposition step. The DSSCs can be considered to be electrochemical devices consisting of (a) a photoanode which has a thick film of a wide band gap oxide semiconductor (like TiO2), typically coated on a transparent conductive oxide (TCO) glass substrate, with TiO2 being sensitized with adsorbed dyes that absorb visible light, (b) an electrolyte that establishes the internal electrical continuity between anode and counter electrode and mainly plays the role of regenerating the dye such that the photoexcitation, electron injection and current fl...

Nonhydrolytic Route for Synthesis of ZnO and Its Use as a Recyclable Photocatalyst

Abstract: A simple, convenient and versatile synthetic approach has been demonstrated for large-scale synthesis of zinc glycerolate microcrystals having preferential growth along the (100) axis. Glycerol has been used both as a ligand and as a solvent. This glycerolate precursor has subsequently been converted into the hexagonal phase of zinc oxide (ZnO) with wurtzite structure by calcining in air. A number of techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, solid-state 13C NMR spectroscopy, and thermogravimetric analysis (TGA) measurements have been used to investigate the morphology, crystallinity, and structure of the products obtained before and after calcination. Furthermore, the room-temperature photoluminescence (PL) of the ZnO nanocrystals has also been investigated along with rhodamine B degradation. The latter has been used as a probe reaction to evaluate the photocatalytic performance...

Zinc glycolate: a precursor to ZnO.

Abstract: A simple and versatile solvent-growth process using ethylene glycol has been demonstrated for the synthesis of novel faceted bipyramidal zinc glycolate. Upon thermal treatment in air, this structur...

A facile nonaqueous route for fabricating titania nanorods and their viability in quasi-solid-state dye-sensitized solar cells

Abstract: A facile and simple process has been detailed for the synthesis of titanium glycerolate nanofibers using glycerol as both a solvent and a chelating agent. This complex has then been successfully converted to a high surface area anatase phase of titanium dioxide (TiO2) through solid state transformation without alteration in the overall fiber morphology. The structure, crystallinity and morphology of the products before and after transformation have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), solid-state 13C NMR and thermogravimetric analysis (TGA) measurements. As a demonstration of a potential application, these anatase nanorods (NRs) have been used as a photoanode to fabricate a dye-sensitized solar cell (DSSC) using a gel polymer electrolyte. Devices with efficiencies of 2.8% and 4.4% were recorded under light intensity of 100 mW/cm2 and 10 mW/cm2 illumination respectively.

Thiophene-modified perylenediimide as hole transporting material in hybrid lead bromide perovskite solar cells

Abstract: A small molecule based on N,N′-dialkyl perylenediimide (PDI) as core derivatized with thiophene moieties (Th-PDI) was synthesized. Its HOMO (highest occupied molecular orbital) level was measured to be between 5.7 and 6.3 eV vs. local vacuum level depending on doping and measurement method. Th-PDI was successfully applied as hole-transporting material (HTM) in CH3NH3PbBr3 hybrid perovskite solar cells. Three different cell architectures, each with a different mode of operation, were tested: (1) using a mesoporous (mp) TiO2 substrate; (2) mp-Al2O3 substrate; (3) planar dense TiO2 substrate. The first gave the best overall efficiency of 5.6% while the mp-Al2O3 gave higher open-circuit photovoltage (VOC) but lower efficiency (2.2%). The cells exhibited good reproducibility with very little J–V hysteresis (the mp-Al2O3 showed a more appreciable hysteresis of individual photovoltaic parameters but little dependence of efficiency on scan direction). Storage of unencapsulated cells in 25–30% relative humidity demonstrated fairly good stability with <20% efficiency drop after 37 days. While further optimization of each layer in the device is needed, the synthetically-simple new molecule shows promise as an inexpensive and readily-doped HTM for use in photovoltaic cells where a deep HOMO level is needed.

Cesium Enhances Long-Term Stability of Lead Bromide Perovskite-Based Solar Cells.

Abstract: Direct comparison between perovskite-structured hybrid organic–inorganic methylammonium lead bromide (MAPbBr3) and all-inorganic cesium lead bromide (CsPbBr3), allows identifying possible fundamental differences in their structural, thermal and electronic characteristics. Both materials possess a similar direct optical band gap, but CsPbBr3 demonstrates a higher thermal stability than MAPbBr3. In order to compare device properties, we fabricated solar cells, with similarly synthesized MAPbBr3 or CsPbBr3, over mesoporous titania scaffolds. Both cell types demonstrated comparable photovoltaic performances under AM1.5 illumination, reaching power conversion efficiencies of ∼6% with a poly aryl amine-based derivative as hole transport material. Further analysis shows that Cs-based devices are as efficient as, and more stable than methylammonium-based ones, after aging (storing the cells for 2 weeks in a dry (relative humidity 15–20%) air atmosphere in the dark) for 2 weeks, under constant illumination (at max...

Cesium Enhances Long-Term Stability of Lead Bromide Perovskite-Based Solar Cells

Abstract: Direct comparison between perovskite-structured hybrid organic-inorganic - methyl ammonium lead bromide (MAPbBr3) and all-inorganic cesium lead bromide (CsPbBr3), allows identifying possible fundamental differences in their structural, thermal and electronic characteristics. Both materials possess a similar direct optical band-gap, but CsPbBr3 demonstrates a higher thermal stability than MAPbBr3. In order to compare device properties we fabricated solar cells, with similarly synthesized MAPbBr3 or CsPbBr3, over mesoporous titania scaffolds. Both cell types demonstrated comparable photovoltaic performances under AM1.5 illumination, reaching power conversion efficiencies of ~6 % with a poly-aryl amine-based derivative as hole transport material. Further analysis shows that Cs-based devices are as efficient as, and more stable than methyl ammonium-based ones, after aging (storing the cells for 2 weeks in a dry (relative humidity 15-20%) air atmosphere in the dark) for 2 weeks, under constant illumination (at maximum power), and under electron beam irradiation.

Synthesis of ZnO/Au and ZnO/Ag nanoparticles and their photocatalytic application using UV and visible light

Abstract: We report a simple and convenient method for the synthesis of a ZnO/Au and ZnO/Ag heterostructure nanoflower by applying a surfactant mediated route. Initially, pure ZnO nanoflowers have been synthesized followed by Au and Ag deposition on ZnO surface using hydrazine hydrate as reducing agent. Structure, crystallinity, and morphology have been assessed by X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy techniques. The influences of the deposited metal nanoparticles (Au and Ag) on the surface of ZnO have been emphasized by applying the as-synthesized nanostructure in dye degradation under illumination of UV and visible light. The basic motivation behind this work is to find a superior photocatalyst, which can work under UV as well as visible light i.e., to cover the whole range of the solar spectrum. Photocatalytic performances of bare ZnO, ZnO/Au, and ZnO/Ag have been studied thoroughly. Photodegradation results under UV and visible light demonstrated that the incorporation of noble metal nanoparticles significantly (or drastically) increases the catalytic efficiency by promoting the photogenerated charge carrier separation. The main advantage of the proposed ZnO/Au and ZnO/Ag semiconductor is that it delays the recombination process of the electron–hole pairs generated by the photon absorption, which in lieu increases the photocatalytic efficiency. It is a challenging issue to fabricate stable photocatalysts which can work under visible light as it covers 43% of sunlight. To investigate the role of photogenerated electrons and holes in dye degradation, scavenging experiments using different scavengers have also been performed.