Abstract
The 2-{4-[2-benzylidenehydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 1), 2-{4-[2-(1-naphthylmethylene)hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 2) and 2-{4-[2-(9-anthrylmethylene)- hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 3) were synthesized by direct tricyanovinylation of hydrazones. The bathochromic shift in absorption spectra has been observed by increasing the solvent polarity. The FTIR spectra of these new dyes exhibited three important absorption bands. The first band centered near 3260 cm-1 in System 1 while 3208 cm-1 and 3211 cm-1 in System 2 and System 3 for the nNH absorption, respectively. The second band is a sharp absorption band in the region of 2212-2209 cm-1, which was attributed to the cyano group absorption. The third is an absorption band in the region of 1611-1603 cm-1 ascribed for the C=N. Density functional theory (DFT) calculation of relative energies, relative enthalpies and free energies shows that E isomers are the most stable except System 3 in which the most stable is Z isomers. The conformational energy profile shows two maxima near (-90 and 90o) while three local minima observed at (-180, 0 and 180) for N1-N2-C1-C2 torsional angle. The highest occupied molecular orbitals (HOMOs) are localized on the whole molecules while lowest unoccupied molecular orbitals (LUMOs) are distributed on the tricarbonitrile. KEY WORDS: Dye-sensitized solar cells, HOMO, LUMO, Absorption, FTIR spectra Bull. Chem. Soc. Ethiop. 2015, 29(1), 137-148DOI: http://dx.doi.org/10.4314/bcse.v29i1.13
Highlights
The basic design of today’s high performance dye sensitized solar cells (DSSC) was developed in the early 1990’s by Grätzel et al [1]
The C-C, C-N and NN bond lengths of E and Z isomer of all the investigated systems are almost same while the C9C10 in Z isomer of System 2 and System 3 stretched compared to System 1
The lowest unoccupied molecular orbitals (LUMOs) energies of studied dyes are above the conduction band of TiO2
Summary
The basic design of today’s high performance dye sensitized solar cells (DSSC) was developed in the early 1990’s by Grätzel et al [1]. They have great potential applications in the fields of electronics, optics, catalysis and energy storage/conversion [1]. It is assumed that the world energy demand will increase by about 70% between 2000 and 2030. Fossil fuels are facing rapid resource depletion which is supplying 80% of all energy consumed worldwide. The resource reserves of fossil fuels throughout the whole world in 2002 were projected to last 40 years for oil, 60 years for natural gas and 200 years for coal. In order to achieve this, the integration of multiple excellent chromophores is necessary, and the energy transfer within the system should
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