Development of polyacrylamide-co-acrylic acid/ sodium carboxy methyl cellulose/ sodium sulfide polymer electrolyte for photovoltaic applications

Abstract

Today, the development of photovoltaic (PV) technology based on solar energy is vital to overcome the continuous depletion of fossil fuels which bring various environmental impacts particularly global warming and air pollution. The electrolyte of a PV cell is one of the most essential components. Highly efficient electrolyte is crucial for high performance photovoltaic cell. Liquid electrolytes have yields to produce high efficiency cell over other types of electrolytes, however, it has drawbacks of leakage and corrosion with low volatility. To overcome these issues, solid electrolytes motivate us to undertake among the most promising candidates due to excellent chemical and physical stability, improved durability with wider operating temperature and stay steady. Therefore, this research was intended to develop a highly efficient solid electrolyte. In this study, a solid polymer electrolyte (P-Na-S) comprising poly(acrylamide-co-acrylic acid), sodium carboxymethylcellulose (Na-CMC), sodium sulfide (Na2S) blend has been fabricated by solution casting method. To fabricate solid polymer electrolytes containing of (P-Na-S), with and without ethylene carbonate (EC) as plasticizer. The concentration of Na2S was added with varied range from 10 to 50 wt.% salt. Electrochemical Impedance Spectroscopy (EIS) technique, FTIR and XRD were used to characterize electrical and optical properties. Consequently, polymeric plasticizer, ethylene carbonate (EC), was then added to the certain amount of (P-Na-S) to investigate the effect of the plasticizer on the electrolyte performance. The EC concentration was varied from 10 to 50 wt%. Based on the electrical conductivity measurement, the optimum electrolyte composition was found to be 30 wt.% Na2S salt and 40wt.% EC plasticizer. The highest conductivity of further salt was 9.82 x 10-7 Scm- 1 achieved at 30 wt.% Na2S. The addition of EC from 10 to 50 wt.% caused an increase in the conductivity from 1.06 x 10-6 at 10 wt.% EC to the maximum 2.74± 2.52 x 10-4 Scm-1 at 40wt% EC which signify (P-Na-S)-EC. From the impedance measurements, the lowest activation energy for the electrolyte without EC was 0.36 eV, which was estimated for the electrolyte of30wt% N a2S. Meanwhile, for the electrolyte with 40wt% EC, a minimum activation energy dropped to 0.16 eV. This study gives a comprehensive description of electron transport through intramolecular circuits of covalent bonds and ionic compound from tunneling to thermally activated hopping. It exhibits that higher conductivity is associated with lower activation energy. FTIR measurements revealed that the peaks of the relevant functional groups shifted when the different concentrations of Na2S salt and EC were added, indicating chemical interactions among materials added. XRD analysis showed the polymer electrolyte improved largely the amorphous region when N a2S was added. However, the addition of EC increased again crystallinity. This work explores based on ion activities and movement of these electrolyte systems.