Design and synthesis of organic dyes with various donor groups: promising dyes for dye-sensitized solar cells

The present work is involved in the computational and experimental studies of organic dyes and their applications as dye-sensitized solar cells (DSSCs). This comprised the study of three hydrazone-based sensitizers (E)-2-cyano-N '-((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide (CHMA), (E)-2-cyano-N '-(4-(dimethylamino)benzylidene)acetohydrazide (CDBA), (E)-N '-(anthracen-9-ylmethylene)-2-cyanoacetohydrazide (AMCH) that have been prepared and confirmed by means of several analytical procedures like Fourier transform infrared, UV-visible and nuclear magnetic resonance techniques to investigate the best possible selection for DSSCs by computational and experimental techniques. The computational methods are applied to optimize the structures of prepared organic dyes via density functional theory (DFT) method at B3LYP/6-311G(p,d) level of theory. The time-dependent DFT (TD-B3LYP/6-311G**) was used with and without solvent to find out the absorption spectra and matched with the experimental data and the electro-optical and reorganization energies of prepared dyes were further investigated. The results revealed that the prepared dyes would be better sensitizers for DSSCs because of small highest-occupied molecular orbital-lowest-unoccupied molecular orbital energy gap. Moreover, on the basis of the above results, we fabricated the devices via the doctor blade method to study the photovoltaic performance with the prepared dyes (CHMA, CDBA and AMCH). The dye AMCH exhibited the maximum efficiency with commercial TiO2.