Asok K. Jana

Studies on storage photoelectrochemical cell consisting of phenazine dye-EDTA and different redox couples

A new type of photoelectrochemical cell has been developed using phenazine dye and EDTA aqueous solution and aqueous solution of different redox couples separated by a Pyrex sintered glass membrane (porosity G-4). The different phenazine dyes used are phenosafranin. safranin-O, safranin-T, and neutral red. The redox couples used are Cu+Cu2+, Fe(CN)64−Fe(CN)63−, I−I2, and solFe2+Fe3+. An interesting observation is that the growth of maximum photovoltage takes 15–25 min, whereas the decay to the original dark voltage requires two to three days. Cell characteristics such as open-circuit voltage, short-circuit current, fill factor, power efficiency, and solar energy efficiency have been determined.

Enhancement in power output of solar cells consisting of mixed dyes

A new type solar cell consisting of dye-redox system have been developed. Instead of single dye, mixture of two dyes along with a reducing agent, EDTA was taken in the illuminated compartment of an H-shaped cell in which I−/I2 redox couple in the dark compartment are separated by glass membrane (Porosity G-4). The dyes used for mixed system are of four classes: phenazine, thiazine, xanthene and acridine. Calculated solar energy efficiency (SEE) and other cell characteristics of mixed dye-solar cell is larger in comparison to the cell with single dye.

A thin-film solar cell consisting of phenosafranin in a polymer matrix

A p-n junction solar sandwich cell has been constructed with phenosafranin dye in a thin film of polyvinyl alcohol placed between a semitransparent conducting glass coated with indium oxide and a platinum foil. A large increase of photovoltage has been observed when the phenosafranin is used in the thin film rather than in the solid polycrystalline state.

Absorption spectra of nitroanilines in micellar solution-II

The absorption spectra of nitroanilines (o-, m- and p-) in aqueous and nonaqueous solution of neutral surfactant-Triton X-100 (TX-100) reveal many interesting phenomena. Nitroanilines and TX-100 behave as electron acceptor and donor, respectively, in both media during charge-transfer (CT) complex formation though water plays an important role in aqueous media. The thermodynamic and spectrophotometric parameters of nitroanilines-TX-100 interactions in two media have been determined and the electron accepting capability among the nitroanilines have been also established. In addition to this, role of surface in CT interaction, the site of CT interaction, intensity and stability of CT interaction between nitroanilines and TX-100 have been pointed out.

Storage solar cell consisting of phenosafranin-EDTA in surfactant solution

Abstract A new photoelectrochemical cell consisting of phenosafranin, a cationic phenazine dye, and ethylenediaminetetraacetic acid in surfactant solution, separated from a saturated aqueous solution of iodine by a Pyrex sintered glass membrane, has been developed. The different surfactants used were cetyltrimethylammonium bromide (CTAB; cationic), sodium lauryl sulphate (SLS; anionic) and Triton X-100 (neutral). The results show that the electrical performance of the cell is decreased in SLS, increased slightly in Triton X-100 and increased appreciably in CTAB compared with the cell without surfactant. The possible mechanisms of the cell in the various surfactants are discussed.

Photoelectrochemical and spectral studies of phenosafranin in different reducing agents

Abstract The photovoltages developed in systems consisting of phenosafranin dye and different reducing agents such as Fe 2+ , I − , Fe(CN) 6 4− , Cu + , and EDTA in deoxygenated aqueous solutions have been found to correlate with the oxidation potentials of the reducing agents. From the absorption and fluorescence spectra of phenosafranin in these reducing agents, the equilibrium constants ( K c ), the Stern-Volmer constants ( K sv ), as well as quenching rate constants ( K q ) have been determined which also show the same correlation.

Absorption spectra of 7, 7, 8, 8-tetracyanoquinodimethane in micellar solutions

The absorption spectra of 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) with nonionic surfactant. Triton X-100, anionic surfactant, SLS and cationic surfactant, CTAB in aqueous and nonaqueous media have been studied. The spectral studies show that TCNQ forms 1:1 charge-transfer (CT) complex with Triton X-100 in both media. The aqueous solution of TCNQ shows an absorption maxima at 610 nm, which is unperturbed in the presence of SLS but is shifted to 650 nm in the presence of CTAB, indicating the interaction of TCNQ with the cationic surfactant and not with the anionic surfactant. In addition to this, the stability of TCNQ-Triton X-100 complex has been determined and the probable site of CT interaction has been pointed out.

Photoelectrochemical cells consisting of phenosafranin-EDTA and different redox couples with illuminated semiconductor electrode

A photoelectrochemical cell, semiconductor(In[sub 2]O[sub 3])/dye-EDTA // redox couple/Pt, has been developed using phenosafranin dye and EDTA aqueous solution in one compartment and Cu[sup +]/Cu[sup 2+], Fe(CN)[sub 6][sup 4[minus]]/Fe(CN)[sub 6][sup 3[minus]], I[sup [minus]]/I[sub 2], and Fe[sup 2+]/Fe[sup 3+] in the other compartment of an H-shaped cell separated by a glass membrane. All the cell characteristics such as open-circuit voltage, short-circuit current, fill factor, power efficiency, and solar energy efficiency have been determined. There is 2-3 fold increase of efficiency of the cell compared to the same cell with illuminated Pt electrode.

Solar cells consisting of phenazine dyes in polymer matrix

We have constructed p−n heterojunction solar sandwich cells with phenazine dyes in a thin film of polyvinyl alcohol placed between a conducting glass coated with indium oxide and a platinum foil. The current-voltage relations of the cells have been measured in the dark and light under both forward and reverse biases.

Kinetics of temperature-dependent photoinduced redox reactions in a photoelectrochemical cell

Abstract The effect of temperature on the electrode kinetics of photovoltage generation in photoelectrochemical (PEC) cells consisting of a phenazine dye-EDTA system, separated from an aqueous solution of an electron acceptor like iodine by a salt bridge has been studied. The phenazine dyes used are phenosafranin, safranin-O, and safranin-T. The maximum photovoltages (Voc) generated and the sunlight engineering efficiency (SEE) have been found to increase with increasing temperature, but there is a fixed critical temperature for each dye above which the Voc decreases: 29°C for phenosafranin, 35°C for safranin-T, and 40°C for safranin-O. The photovoltage growth and decay follow the functional forms related to the relaxation times. The rate constants for the forward and backward reactions have been calculated from these relaxation times at different temperatures. The rate of the photoinduced chemical reaction increases with an increase in temperature from 20°C–50°C for all the dyes, with concomitant decrease for the backward reaction. The free energies of electron transfer across the electrode/electrolyte interface have been calculated. The activation energies calculated from the rate constants at different temperatures for phenosafranin-EDTA, safranin-T-EDTA, and safranin-O-EDTA reactions are 5.14, 5.60, and 5.63 kJ mol−1 respectively.