Impacts of dye extracting solvents and pH on the stability of the oxalis triangularis as dye sensitizer by time-varying on DSSCs

Dye a sensitized solar cell (DSSC) is expected to be a potential leader in the technology of solar cells in the future. The low-cost manufacturing of this technology offers an alternative to the silicon-based solar cells. Realizing the low efficiency and rapid degradation of DSSCs, researchers are lead to analyze the factors to maintain its stability. In this paper, DSSC was fabricated by using natural dye, Oxalis Triangularis, with varying different solvents; ethanol, water and pure dye. The degradation trends and stability of the extracting dye in each solvent was observed by time-variation analysis. The degradation of extracted dye was observed at 0 min, 30 mins, 1 hour, 2 hours, 24 hours, 25 hours and 48 hours. As for the extracting solvent, ethanol yields a better performance by maintaining its stability for 48 hour, while for water solvent, the DSSC starts to degrade after 25 hour being fabricated. The highest efficiency of Oxalis Triangularis is achieved in ethanol solvent about 0.05907% with Voc 0.0810mV, Isc 0.0204mA/cm2, FF 614.5 at 2 hours, followed by in water solvent about 0.09540% with Voc 0.1359mV, Isc 0.0268mA/cm2, FF 3.6434 at 30 minutes and pure dye 0.00032% with Voc 0.1305mV, Isc 0.1721mA/cm2, FF 397.3 after 25 hours. Then, Oxalis Triangularis was extracted in different pH which pH 2.3, pH 3.2, pH 5, pH 7, pH 7.5, pH 7.8 for 0 min and after 1 hour. Oxalis Triangularis achieved high-energy conversion efficiency about 2.619×10-6%, at the high acidity and 4.53×10-6%, for alkaline pH value, which is at pH 2.5 and pH 7.8, respectively. Nevertheless, after one hour, the efficiency of each pH values was changed about 0.006×10-6% for pH 2.5 and 2.219×10-6% for pH 7.8 due to the oxidation and chemical reaction of the dye solution. The results discussed in this paper describe the acceptable optimum time for fabrication before degradation started to occur after the DSSCs being stored at room temperature.