On the azo dyes derived from benzoic and cinnamic acids used as photosensitizersin dye-sensitized solar cells

Abstract

In order to get a better insight into the relationship between molecular structure and photovoltaic performance, six monoazo dye molecules containing benzoic and cinnamic acid moieties were synthesized and their photovoltaic properties were studied. Three of them have not been previously used in solar cells. Spectroscopic measurements of the investigated compounds coupled with theoretical calculations were performed. Short-circuit current density, open-circuit voltage, and fill-factor were determined. It was found that a larger amount of short-circuit current density will be generated if the HOMO-LUMO energy gap is lower, determined by the stability of the molecule and the electronic effect of the donor moiety. Among both series of synthesized dye molecules, the highest obtained values of short-circuit current density were achieved with (2-hydroxynaphthalene-1-ylazo)benzoic acid and (2-hydroxynaphthalene-1-ylazo)cinnamic acid, and thus they were regarded as promising candidates for application in dye-sensitized solar cells.

A detailed UV–Vis spectral investigation of six azo dyes derived from benzoic- and cinnamic acids: experimental and theoretical insight

“…The FT-IR, 1 H and 13 C NMR spectroscopic characterization provided data that confirmed the existence of the hydrazone tautomeric forms of A1 and A2 and the azo forms for B1 and B2 in the solid state and DMSOd 6 [6]. As for the ester A2a, the same occurrence as with A1 and A2 could be observed.…”

“…All the investigated azo dye molecules were synthesized by a diazo-coupling reaction between the appropriate diazonium salt and the corresponding coupling reagent. The detailed synthetic procedures, as well as the thorough characterization of the selected compounds, have been provided in the previous paper, including melting points, FT-IR, 1 H and 13 C NMR spectroscopic analysis [6]. The UV-Vis 1700 Shimadzu spectrophotometer was used to provide the absorption spectra of dye molecules at room temperature.…”

“…Recent experimental results [6] showed that the molecules of the A-series exist in the hydrazone tautomeric form, while the molecules in the B-series exist exclusively in the azo form. In order to verify these observations, a DFT analysis of possible tautomeric forms for these two series was performed.…”

“…Therefore, the determination of the exact structural forms in a different environment (solvents, acidic and basic medium) for the investigated compounds is essential, since they exhibit azohydrazone tautomerism and thus different charge distributions. Although four of them exhibit the tautomeric property from a theoretical standpoint, for the purpose of the previous research, only two systems were investigated [6].…”

Spectroscopic Behaviour of Two Novel Azobenzene Fluorescent Dyes and Their Polymeric Blends

“…On the other hand, the ability of azobenzene compounds to reversibly change from the stable trans-isomer to cis form upon photoirradiation (photoisomerization) causes nonradiative deactivation and very small/negligible fluorescence. The rapid photoisomerization of the azo bridge finds applications in on-off photoswitching techniques, such as in optical data storage, dye-sensitized solar cells, pharmaceuticals, and non-linear optics [2][3][4][5][6][7][8]. Azo-containing molecules can play the Scheme 1.…”