New derivatives of azopyrazolo dyes: Synthesis and optical characterization for application in sensitized solar cells

Abstract

Several novel pyrazolotriazine azo scaffolds were synthesized by the diazotization of 4-aminoacetanilide and coupling with 3-Aminocrotonitrile and then refluxed with hydrazine hydrate to furnish 4-(4-acetamidophenylazo)-3-amino-5-methyl-1H-pyrazol. The later scaffolds was diazotized and coupled with active methylene compounds namely; (malononitile, and ethyl cyanoacetate) afforded the corresponding novel pyrazolotriazines derivatives. All freshly synthesized scaffolds were elucidated by using FT-IR, 1H NMR, M S and elemental analysis, and they were evaluated for their sensitized solar cells to show promising results. Therefore, thin films of these dyes were prepared by using thermal evaporation technique. Optical properties of these films were conducted by employing the UV–vis-IR spectroscopy. Result of optical investigation indicated that the direct forbidden transition was the most probable transition. The high value and broad spectrum of absorption coefficient of these films in the UV and visible regions of spectra recommended its application in design of photovoltaic devices.