Suresh Thogiti

Comparison of triphenylamine based single and double branched organic dyes in dye-sensitized solar cells

A series of single and double branched organic dyes (1–4) utilizing two different acceptor groups, 2-cyanoacetic acid and rhodanine-3-acetic acid as anchoring moieties, were synthesized and characterized for their potential in dye sensitized solar cells (DSSCs). The DSSC based on sensitizer 3 has the best power conversion efficiency (3.51%) among all the devices assessed, which was 2 times higher than that of 1 with only one anchoring group. Compared to the 1–2 congeners with only one anchor, the dianchoring dyes 3–4 could suppress charge recombination more effectively and increase the electron injection efficiency, leading to a higher open-circuit voltage and short-circuit current.

Discrete photoelectrodes with dyes having different absorption wavelengths for efficient cobalt-based tandem dye-sensitised solar cells

A pn-tandem dye-sensitised solar cell (pn-DSSC) employing a set of sensitisers with complementary absorption spectra and a less-corrosive cobalt-based electrolyte is presented. We applied three organic sensitisers (denoted C343, DCBZ, and SQ) featuring different absorption wavelengths for the p-DSSC, while keeping the n-DSSC sensitiser (denoted DCA10CN2) constant. Characterisation of the Co+2/+3-based DSSC devices revealed that SQ dye, with a longer absorption wavelength, showed broader spectra and increased photocurrent activity in the visible and near-infrared region compared to the other two devices with C343 and DCBZ in the pn-DSSCs. As a result, the short-circuit current density increased significantly to 4.00 mA cm−2, and the devices displayed overall power conversion efficiencies of as high as 1.41%, which is comparable to that of the best pn-DSSCs in the literature. Our results demonstrate that complementary absorption between the two photoelectrodes is important for enhancing the photovoltaic performance of pn-DSSCs.

Application of CBZ dimer, C343 and SQ dye as photosensitizers for pn-tandem DSCs

A pn-tandem dye-sensitized solar cell (pn-DSC) was prepared with three different sensitized dyes CBZ Dimer (CBZD), C343, and SQ in two different compartments of the n-type or p-type cells. The constructed tandem solar cell was exhibited considerable improvement in experimental pn-DSCs parameters, open-circuit voltage, short-circuit current, fill factor, etc. These results were achieved under air mass 1.5 illumination with three different sensitized dyes in the upper and lower compartment of the pn-DSCs. These results demonstrate a complementary absorption among the two photoelectrodes in the pn-DSCs is a good approach to the efficient and low cost pn-DSCs.

Effect of LiI/I2 concentration and photoelectrode thickness on the photovoltaic properties of NiO-based p-type dye-sensitized solar cells

ABSTRACT In this paper, we have studied the effect of LiI and I2 concentrations on the photovoltaic properties of dye-sensitized solar cells (DSSCs) based on NiO. For all concentrations of iodine, the photo-voltage (VOC) and current density (JSC) increased with increasing LiI concentration. The increment in JSC is ascribed to the higher charge transport efficiency of the device. In addition, the effect of NiO film thickness on the efficiency of the as-fabricated DSSCs was investigated, and an optimum efficiency of 0.0587% was obtained for the DSSC with a double-layer NiO film.

Effect of Iodine Concentration in the Quasi-Solid State Electrolyte on the Photovoltaic Performance of Dye-Sensitized Solar Cells

In the present study, the effect of iodine concentration on the photovoltaic properties of dye sensitized solar cells (DSSCs) based on the quasi-solid state electrolyte has been investigated. The electron transport properties and interfacial recombination kinetics have been evaluated by electrochemical impedance spectroscopy (EIS). It is found that increasing the concentration of iodine decreases the open-circuit voltage (Voc) whereas short circuit current density (Jsc) and fill factor (FF) shows improvement. The increment in Jsc for 0.05 M I2 concentration is ascribed to the decreased charge transfer resistance value obtained by EIS analysis. In addition increasing the concentration of I2 decreases the Voc which is attributed to the increased recombination with tri-iodide ions (I3−) as verified from the EIS analysis under dark condition.

The Effect of Difference Molar Ratios of Dibromo-EDOT as Hole Transporting Material for Solid State Dye-Sensitized Solar Cells

The dye-sensitized solar cells (DSSCs) are one of the promising organic photovoltaic cells due to their low cost, flexibility, and relatively good efficiency. Nevertheless, utilization of liquid electrolyte in DSSCs brings practical problems for commercialization, which leads to solid-state dye-sensitized solar cells (ssDSSCs), that based on organic conducting polymers or inorganic p-type semiconductors as hole transport materials (HTM). A one-side ssDSSCs fabricated here, with a conductive polymer Dibromo-EDOT as an HTM, and also check ssDSSCs efficiency by variation of the HTM concentrations. The morphology of cells examined through SEM, and intensity-modulated photocurrent/voltage spectroscopy, measurements were used to elucidating the electrochemical properties of ssDSSCs. We also optimize the blocking layer thickness and different molar ratios of HTM for the best efficient ssDSSCs.

Effect of electrolyte redox potentials on the photovoltaic performance in dye-sensitized solar cells based on porphyrin dye

ABSTRACT We have investigated the effect of two different kinds of cobalt electrolytes on the photovoltaic performance in dye-sensitized solar cells (DSSCs) using the established porphyrin dye (YD-2). We have characterized the photovoltaic performance of DSSCs containing iodide/triiodide and two different Co3+/2+ electrolytes to confirm the relationship between redox potential of cobalt(III/II) tris(2,2′-bipridine), [Co(bpy)3]3+/2+, cobalt(III/II) tris(1,10-phenanthroline), [Co(phen)3]3+/2+ and the photovoltaic characteristics in DSSCs. Compared to the iodine-based electrolyte, the photovoltage of the DSSCs based on [Co(phen)3]3+/2+ was increased by 15%. The current densities in [Co(bpy)3]3+/2+ and [Co(phen)3]3+/2+-based devices decrease due to their larger size and decrease in difference bewteen HOMO level of dye and redox potential of electrolytes.

Synthesis and investigation of triphenylamine-based double branched organic dyes for p-type dye-sensitized solar cells

ABSTRACT Two double branched organic dyes (T1I and T2I) were synthesized, characterized, and employed as photosensitizers in p-type dye-sensitized solar cells (p-DSSC); we have compared with corresponding single branched dye (TC1) and reference dye P1. The absorbance of the dyes in solution was red shifted and the oxidation potential gradually decreased with increasing the donating ability. It was found that modification from single branched (TC1) to double branched (T1I and T2I) system resulted in increased photocurrent density leading to the higher photovoltaic performances. The charge transporting ability is increased with the introduction of double branching, as evidenced from electrochemical impedance analysis.

Improved performance of dye-sensitized solar cells based on solution treated PEDOT as efficient counter electrode

ABSTRACT The dye-sensitized solar cell (DSSC) is a promising alternative to the Si solar cell because of its low-cost and easy fabrication. The conductive polymer counter electrode, PEDOT has attracted much attention on DSSCs. To enhance efficiency, the electrochemical deposition of PEDOT onto FTO glass was carried out in 4 solution deposition ratios 4:6, 6:4, 8:2 and 9:1 of distilled water and acetonitrile. The best efficiency of the resulting DSSCs with 9:1/ PEDOT as compared to the reference cell. The excellent photoelectric properties, and low cost allow the PEDOT electrode to be a credible alternative electrode for use in DSSCs.

Fluorescent material concentration dependency: Förster resonance energy transfer in quasi-solid state DSSCs

Förster resonance energy transfer (FRET) is critical for wide spectral absorption, an increased dye loading, and photocurrent generation of dye-sensitized solar cells (DSSCs). This process consists of organic fluorescent materials (as an energy donor), and an organic dye (as an energy acceptor on TiO2 surfaces) with quasi-solid electrolyte. The judicious choice of the energy donor and acceptor facilitates a strong spectral overlap between the emission and absorption regions of the fluorescent materials and dye. This FRET process enhances the light-harvesting characteristics of quasi-solid state DSSCs. In this study, DSSCs containing different concentrations (0, 1, and 1.5 wt%) of a fluorescent material (FM) as the energy donor are investigated using FRET. The power conversion efficiency of DSSCs containing FMs in a quasi-solid electrolyte increased by 33% over a pristine cell. The optimized cell fabricated with the quasi-solid state DSSC containing 1.0 wt% FM shows a maximum efficiency of 3.38%, with a short-circuit current density (JSC) of 4.32 mA/cm−2, and an open-circuit voltage (VOC) of 0.68 V under illumination of simulated solar light (AM 1.5G, 100 mW/cm−2).