Impact of Electrolytes Based on Different Solvents on the Long Term Stability of Dye Sensitized Solar Cells

• Published in: Electrochimica acta 2015-06, Vol.168, p.111-115
• Main Authors: Mohanty, Shyama Prasad, Bhargava, Parag
• Format: Article
• Language: English
• Subjects: Aging; N-methyl-2-pyrrolidone; Sealant; Zinc leaching
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2015.03.202

•Aging studies were carried out under heat (60°C) and illumination with DSSCs.•DSSCs with MPN, PC and GBL showed decrease in performance over 60 days.•With NMP, increase in JSC and efficiency was observed whereas VOC decreased.•Leaching of Zn2+ from sealant and desorption of NMP from TiO2 are possible causes. The present article demonstrates the effect of different solvents used in the preparation of electrolyte on the photoelectrochemical characteristics of dye sensitized solar cells (DSSCs) aged under heat (60°C) and illumination for 60 days. The study has been carried out with four different solvents: 3-methoxypropionitrile (MPN), N-methyl-2-pyrrolidone (NMP), propylene carbonate (PC) and γ-butyrolactone (GBL) which differ in terms of donor number, viscosity and dielectric constant. For DSSCs with electrolytes based on MPN, PC and GBL as solvents, performance decreases with time. In contrast, for DSSC with NMP as solvent in electrolyte, increase in JSC and hence, efficiency up to 15 days has been observed followed by a gradual decrease, but remaining above its initial value after 60 days. However, VOC of such cell decreases with time. There are two possible causes for the above observations. Desorption of NMP molecules from titania surface occurred with aging. Secondly, zinc ions leached into the electrolyte following reaction of NMP with sealant were adsorbed on titania surface. The causes behind aging behavior of cells prepared with different solvent based electrolytes have been analyzed using electrochemical impedance analysis of DSSCs, energy-dispersive X-ray spectroscopy (EDS) of photoanodes and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) of electrolyte containing sealant sample which had also undergone aging under similar condition.