Molecular geometry, synthesis and photovoltaic performance studies over 2-cyanoacetanilides as sensitizers and effective co-sensitizers for DSSCs loaded with HD-2

The design, synthesis and photovoltaic performance of metal-free 2-cyanoacetanilide based organic dyes, SA1-6 have been reported as sensitizers/co-sensitizers in dye sensitized solar cells (DSSCs). All dyes possess the thermodynamic requirements to be applied in DSSCs. The DFT and TD-DFT calculations were completed using Guassian09 package software. The obtained results showed appropriate charge separation between the ground state oxidation potential (GSOP) and excited state oxidation potential (ESOP) levels of the dyes. In addition, there was a good a greement between the theoretical and experimental data. Over co-sensitization, SA1-6 exhibited better efficiency than the main sensitizer HD-2. Among the dyes we synthesized, SA1 displayed improved PCE of 8.02 % with increasing in both V-OC value of 0.682 V and J(SC) value of 20.33 mA/cm(2), whereas the DSSC fabricated with dye HD-2 alone showed PCE of 7.49 % with J(SC) of 19.01 mA/cm(2) and V-OC of 0.63 V. Finally, Electrochemical impedance spectroscopy measurements, beside electron lifetimes of SA1-6 and HD-2, were obtained and are in good agreements with the experimental photovoltaic parameters.