Poly(ethylene oxide) polymer matrix coupled with urea as gel electrolyte for dye sensitized solar cell applications

- Urea was used as a plasticizer for polymer electrolyte in DSSC, for the very first time.
- Urea modified electrolytes shows better ionic conductivity value of 4.28 × 10−4 S cm−1 and diffusion co-efficient of 2.06 × 10−6 cm2 S−1 for GPE containing 4 wt% of Urea.
- Photo-conversion efficiency of 6.82% was achieved for DSSC constructed using GPE containing 4 wt% of Urea.
- An upward shift of ∼160 mV in the conduction band of TiO2 in the case of GPE was determined from Chemical capacitance Vs applied voltage plot.

In this paper, a new series of gel polymer electrolytes modified with various weight percent of urea in Poly(ethylene oxide) polymer matrix and iodine-iodide based redox couple were reported for the application of dye-sensitized solar cell. The effect of urea on both molecular mobility and final morphology of GPE are characterized by Fourier Transform Infrared spectroscopy and Scanning Electron Microscopy. Electrochemical Impedance Spectroscopy and Linear Sweep Voltammetry show that the addition of urea gives a general increment in both ionic conductivity (σ) and tri-iodide diffusion coefficient. In particular, GPE containing 4 wt% of urea has an ionic conductivity, σ = 4.28 × 10−4 S cm−1 and tri-iodide diffusion coefficient, DI3− = 2.06 × 10−6 cm2 s−1. A maximum power conversion efficiency of 6.82% in the photovoltaic performance is achieved. Further, a variation of charge transfer resistance and chemical capacitance at the TiO2/dye/interfaces as a function of bias voltage is observed. It suggests an upward shift in the conduction band of TiO2 in the case of gel electrolytes.

Influence of Urea interaction with polymer on various characteristics of GPE like morphology, Electrochemical impendence, Electron lifetime and Chemical capacitance which leads to better DSSC performance {Liq indicates liquid electrolyte and A, B, C, D and E indicates GPE modified with various wt% of Urea (0%, 2%, 4%, 6% and 8% respectively)}.166