Asymmetric Dual Anchoring Sensitizers/Cosensitizers for Dye Sensitized Solar Cell Application: An Insight into Various Fundamental Processes inside the Cell (original) (raw)

2019, Journal of Physical Chemistry C

In order to study the various fundamental processes occurring inside the DSSC, we have fabricated devices employing newly synthesized diphenylamine based organic dyes with AD -π-A configuration, carrying four different anchoring groups, viz. cyanoacetic acid (DDC), rhodanine acetic acid (DDR), 4-hydrazinylbenzoic acid (DDH), and barbituric acid (DDB), as effective sensitizers/co-sensitizers. In the present work, all the bi-anchoring dyes were subjected to photophysical, electrochemical, thermodynamic, photoelectrochemical and theoretical studies. All of them displayed characteristic λ abs and λ emi in the range of 415-480 and 570-680 nm, respectively. Their optical and electrochemical band gaps were calculated to be in the order of 2.1 to 2.3 eV. The calculated driving forces for electron injection (ΔG inj), recombination (ΔG inj) and regeneration (ΔG reg) processes were found to be negative, showing the feasibility of these processes, while their DFT studies clearly indicated the directional flow of electrons within the dye in the cell. The devices with DDC as sensitizer displayed the highest conversion efficiency of 2.53%, whereas DDB exhibited the maximum of 7.69% when employed as a co-sensitizer along with Ru (II) based HD-2 dye. Finally, EIS circuit fitting was carried out in order to obtain different interface resistance values to study the fundamental processes of energy conversion.