A locust bean and pectin polymer blend integrated with thio-bridged pyridinyl additive as a novel cobalt and copper gel electrolyte system for dye-sensitized solar cells

Abstract

An intensive correlation has been attempted on 2-(pyridin-2-yl)-1-(4-(trifluoromethyl)phenyl)-1H-benzo[d]imidazole ligand-coordinated cobalt and copper metal complex electrolytes (Co2+/3+[ptpbi]3 and Cu1+/2+[ptpbi]2) with blend biopolymer electrolyte based on Locust Bean Gum and Pectin (LP) as a host matrix to enhance the performance of organic DPTCY sensitizer (2D-π-D′-A-π-A). Comparatively, the ligand coupled bulky CF3 acceptor on the para position of benzyl moiety-substituted 2-(pyridin-2-yl)-benzimidazole (on the N–H position) [ptpbi]-coordinated copper metal complex shows a higher redox potential (0.62 V vs NHE) compare to Co2+/3+ redox system. The photovoltaic performance of thio-bridged pyridinyl based organic compounds (MPP and DSP) with/without highly electron-donating substituents (methyl group) as an additive in QSSE host for dye-sensitized solar cell applications has been employed. A thorough investigation has been made for blending polysaccharide polymer-based electrolytes E1 to E4 through DSC, FTIR, UV–Vis spectroscopic techniques. The analysis of assembled device as [TiO2/DPTCY Dye/Mn+/m + redox/additive/LP blend biopolymer/Pt] has achieved a maximum PCE of 5.97% under 1 sun (100 mW cm−2) condition with 1.5AM. These results signify a record for copper complex with methyl-substituted thio-bridged pyridinyl (MPP) with higher efficiency. These devices had shown a higher chemical capacitance (6.06 × 10−6 F), recombination resistance (25.5 Ω), charge transfer resistance (5.67 Ω), ionic conductivity (1.568 (S cm−1) × 10−3), electron lifetime (48.97 ms), diffusion coefficient (2.63 × 10−7 cm−2 s), dielectric constant (2.76 × 102) and dielectric loss (4.41 × 103) compared with other substitution-based additives. These additives have trapped the diffusion of Cu2+ and Co3+ ion species has resulted in the constraint resistance and enhancement of the catalytic effect of the counter electrode. The higher charge relaxation time and a negative shift in the Quasi-Fermi level of TiO2 arise by correlating photocurrent and photovoltage in suppression of recombination reaction.