Synthesis and characterization of cationic starch gel polymer electrolyte for dye-sensitized solar cell application

• Main Author: Lobregas, Michaela Olisha S.
• Format: text
• Language: English
• Published: Animo Repository 2018
• Subjects: Polyelectrolytes; Dye-sensitized solar cells
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5542
• Institution: De La Salle University

Starch-based gel polymer electrolytes are good potential substitutes for conventional synthetic polymer electrolytes due to its low cost, high efficiency, excellent biodegradability and wide availability. However, its limited solubility, intrinsic hydrophilicity and crystalline characteristics limit the ionic conductivity of the electrolyte as well as its efficiency. This study reports the improvement in the starch properties through chemical modification and, the preparation of gel electrolyte using the modified starch as the polymer matrix and imidazolium-based ionic liquid as plasticizer. Potato starch was modified by incorporation of ionic liquid moieties in its chain resulting to cationic starch. The attachment of ionic moiety onto the starch backbone was confirmed by FTIR, 1H-NMR, thermogravimetric and elemental analyses. The cationic starch had high water solubility, flaky morphology, and high gelatinization temperature. The starch gel electrolyte showed enhanced conductivity with increase in ionic liquid content and redox couple (KI/I2) concentration. The optimized composition of the starch gel electrolyte having the highest ionic conductivity and the most efficient migration of I-/I- 3 redox couple contained 1:3 cationic starch: ionic liquid weight ratio and 70% wt KI/I2. Its application in dye-sensitized solar cell (DSSC) had a power conversion efficiency of 0.634%. DSSC with starch gel electrolyte retained 41.67% of its efficiency up to 20 days and has good contact between electrodes. Despite low performance against commercial liquid electrolyte, its better stability and excellent contact filling property makes it a promising electrolyte.