Enhancement of power conversion efficiency of dye-sensitized solar cell via symmetrical Bi-anchoring organic molecules as co-sensitizer

Abstract

A strategy has carried to improvise the photovoltaic performance of DSSCs using auxiliary compounds as co-sensitizer along with organic sensitizer. Herein, bi-anchoring metal-free aromatic organic molecules (A-π-A) based co-sensitizer was utilized with organic sensitizer (DTTCY) and a Co 2+/3+ [bnbip] redox couple incorporated PEG-HEC quasi-solid-state electrolyte for an efficient DSSCs. Interestingly, ACY organic co-sensitized device (typically TiO 2 /ACY/DTTCY/Co 2+/3+ [bnbip]/PEG-HEC/Pt) has achieved a maximum power conversion efficiency of 8.3% under AM 1.5 G illumination (100 mW cm −2 ). At the same instance, NCY and PCY co-sensitized devices achieved comparably lower PCE of 7.44% and 6.99% respectively. These results prove that longer π-conjugation and bi-anchoring group of ACY molecules has induced electron injection process on TiO 2 surface. The influences of co-sensitizer are strongly covered the naked spectrum in the UV region and fill the vacant area in TiO 2 that induces a change in Quasi Fermi level of and decreases recombination flanked by photo-anode and oxidized cobalt species. The PCE results of ACY sensitized device are sustained by some electrochemical factors such as Bulk Resistance (R s = 17.23 Ω), Recombination Resistance (R Rec = 18.84 Ω), Charge Transfer Resistance (R CT = 1.136 Ω), Chemical capacitance (C μ = 13.66 μF), Ionic Conductivity (σ = 2.31 E −03 S cm −1 ), electron lifetime (τ n = 52.85 μs), electron transport time (τ d = 3.29.\μs) and collection efficiency (η COL = 93.97 %), rate of reaction constant (K eff = 18.92 s −1 ), Electron Density (n s = 1.21 E +17 cm −3 ), Dielectric constant (D eff = 0.011 mm 2 s -1 ), Dielectric Length (L n = 0.776 mm). The opportunity of trapping the co-sensitizer system functionalizes the anode surface supposed to avoid back electron transfer and dye degradation. The motive of the study is to enhance the photo-ability of metal-free DTTCY sensitizer along with metal-free co-sensitizer and metal-free additives integrated into the blend polymer electrolyte. • Design and synthesis of (A-π-A) based co-sensitizer for DSSCs application. • PEG-HEC polymer with Cobalt redox couple used as an effective QSS electrolyte. • ACY organic co-sensitized device has achieved a maximum PCE of 8.3%. • ACY co-sensitizer reduces recombination reaction in DSSCs.