Enhancing the performance of dye-sensitized solar cells by incorporating nanosilicate platelets in gel electrolyte

Abstract: Two kinds of gel-type dye-sensitized solar cells (DSSCs), composed of two types of electrolytes, were constructed and the respective cell performance was evaluated in this study. One electrolyte, TEOS-Triton X-100 gel, was based on a hybrid organic/inorganic gel electrolyte made by the sol–gel method and the other was based on poly(vinyidene fluoride-co-hexafluoro propylene) (PVDF-HFP) copolymer. TEOS-Triton X-100 gel was based on the reticulate structure of silica, formed by hydrolysis, and condensation of tetraethoxysilane (TEOS), while its organic subphase was a mixture of surfactant (Triton X-100) and ionic liquid electrolytes. Both DSSC gel-type electrolytes were composed of iodine, 1-propy-3-methyl-imidazolium iodide, and 3-methoxypropionitrile to create the redox couple of I3 −/I−. Based on the results obtained from the I–V characteristics, it was found that the optimal iodine concentrations for the TEOS-Triton X-100 gel electrolyte and PVDF-HFP gel electrolyte are 0.05M and 0.1M, respectively. Although the increase in the iodine concentration could enhance the short-circuit current density (J SC), a further increase in the iodine concentration would reduce the J SC due to increased dark current. Therefore, the concentration of I2 is a significant factor in determining the performance of DSSCs. In order to enhance cell performance, the addition of nanosilicate platelets (NSPs) in the above-mentioned gel electrolytes was investigated. By incorporating NSP-Triton X-100 into the electrolytes, the J SC of the cells increased due to the decrease of diffusion resistance, while the open circuit voltage (V OC) remained almost the same. As the loading of the NSP-Triton X-100 in the TEOS-Triton X-100 gel electrolyte increased to 0.5wt%, the J SC and the conversion efficiency increased from 8.5 to 12mA/cm2 and from 3.6% to 4.7%, respectively. However, the J SC decreased as the loading of NSP-Triton X-100 exceeded 0.5wt%. At higher NSP-Triton X-100 loading, NSPs acted as a barrier interface between the electrolyte and the dye molecules, hindering electron transfer, hence, reducing the cell''s photocurrent density. The same behavior was also observed in the PVDF-HFP gel electrolyte DSSC system. [Copyright &y& Elsevier]