Incorporation of organic additives with electron rich donors (N, O, S) in gelatin gel polymer electrolyte for dye sensitized solar cells

Abstract

A new sequence of GLN gel polymer electrolytes incorporated with KI/I2 redox pair and inexpensive organic additives were prepared. Five dissimilar N, O, and S containing organic compounds were used as additives for the application of DSSCs. The assimilation of organic additives into the GLN gel polymer electrolytes is confirmed by FTIR, DSC, XRD, UV–visible and SEM analyses. EIS analysis reveals that there is an increment in the conductivity up to 2.93X10-5 S/cm for SAA organic additive integrated gel polymer electrolyte than other organic additives. This is owing to more electrons donating nature of the SAA molecule which consists of N, S and O atoms together in its structure. The EIS experiment exposes the interfacial study in DSSCs to elucidate the charge transport mechanisms at the interface of photo electrodes and electrolyte medium of the devices. The charge transfer studies show a lower Rpt (685 Ω), higher Rct (1674 Ω) and Cµ (5.702 X 10-6F) values for SAA integrated GLN gel polymer electrolyte. This confirms mitigation of recombination process between TiO2 and I3- ions and also build a shift to Fermi level of TiO2. DFT calculations also confirm the strength and mode of interaction of individual additives adsorbed on TiO2 surfaces. The FMO analysis clearly reveals that functional groups play a vital role in the charge transfer process at interface materials. The N, O and S present in the SAA additive with GLN gel polymer electrolyte improves the PCE up to 5.8% under the sunlight illumination of 100mWcm−2.