Effect of Lithium Iodide Addition on Poly(ethylene oxide)−Poly(vinylidene fluoride) Polymer-Blend Electrolyte for Dye-Sensitized Nanocrystalline Solar Cell

Abstract

The effect of lithium iodide concentration on the conduction behavior of poly(ethylene oxide)-poly(vinylidene fluoride) (PEO-PVDF) polymer-blend electrolyte and the corresponding performance of the dye-sensitized solar cell (DSSC) were studied. The conduction behavior of these electrolytes was investigated with varying LiI concentration (10-60 wt % in polymer blend) by impedance spectroscopy. A "polymer-in-salt" like conduction behavior has been observed in the high salt concentration region. The transition from "salt-in-polymer" to "polymer-in-salt" conduction behavior happened at the salt content of 23.4 wt %, which is much lower than 50 wt % as generally reported. The electrolyte shows the highest ionic conductivity (approximately 10(-3) S cm(-1)) at the salt concentration above 23.4 wt %. From the evaluation of salt effect on the performances of corresponding DSSC, we find that increasing LiI concentration leads to increased short-circuit photocurrent density (Jsc) caused by enhanced I3(-) diffusion up to an LiI content of 28.9 wt %. Above this limitation, the Jsc decreases as a result of increased charge recombination caused by the further increased I3(-) concentration. The open-circuit voltage (Voc) increases gradually with LiI concentration owing to the enhanced I(-) content in DSSC. The optimized conversion efficiency is obtained at a salt content of 28.9 wt % in the "polymer-in-salt" region, with high ionic conductivity (1.06 x 10(-3) S cm(-1)). Based on these facts, we suggest that the changes of conduction behavior and the changes of I3(-) and I(-) concentrations in the electrolytes contribute to the final performance variation of the corresponding DSSC with varying LiI concentration.

PEO/PVdF–HFP electrolytes for natural dye sensitized solar cell applications: effect of modified nano-TiO2 on electrochemical and photovoltaic performance

“…The presence of fluorine that has a relatively smallest ionic radius and high electro negativity PVDF-HFP is expected to improve the ionic transport and reduce the recombination rate at the semiconductor photoanode and polymer electrolyte interface. And also it is known to be photochemically stable even in & S. Mohanty papers.journal@gmail.com the presence of TiO 2 and Pt, which confirms the suitability in DSSC for long term stability outdoor applications [9]. Another, polymer host PEO based electrolytes have improved the performance and stability, which is originated from the existence of more number of channels between electrodes to maintain the liquid like nature for fast ion transport.…”

Solid state metal-free eosin-Y dye sensitized solar cell based on PVdF-HFP electrolytes: combined effect of surface modified TiO2 and plasticizer on electrochemical and photovoltaic properties

“…Mainly, the conduction at higher concentration of salt is due to the formation of charged ionic clusters. When the electrolyte system approaches the polymer in salt region, the ionic clusters act as transient bridges and connect with each other to form segments of the infinite percolation pathways and exchange the ions [17]. Hence, this way, the ionic conductivity of electrolytes has been increased.…”

“…Among the polymers used in electrochemical device applications, a flouro polymer like PVdF has received great attention because of the presence of fluorine that has the relatively smallest ionic radius and high electronegativity. These features are expected to improve the ionic transport as well as reduce the recombination rate at the semiconding photoanodepolymer electrolyte interface [17]. The CF 2 group present in PVdF structure can give a better compatibility, when it will be blended with other polymers.…”

P(MMA-EMA) Random Copolymer Electrolytes Incorporating Sodium Iodide for Potential Application in a Dye-Sensitized Solar Cell

“…Besides, SPEs have been reported to show promising results for application in DSSCs [2,3]. SPEs are also safer, free from leakage problems, show good thermal stability and are easier to handle for device fabrication [4][5][6].…”