Article

Gelling polysaccharide as the electrolyte matrix in a dye-sensitized solar cell

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Abstract

Hydrophilic polysaccharide, κ-carrageenan, was utilized as the polymer matrix in gel-electrolyte systems for dye-sensitized solar-cell (DSSC) applications. The influence of the solvent system was investigated to optimize the solubility of κ-carrageenan and tetrabutylammonium-iodide (TBAI)/I2 electrolytes by minimizing the water content because of its unfavorable effect on DSSCs. We report herein that two solvent systems, a water/acetonitrile mixed solvent and DMSO, were found to effectively dissolve the components. The composite natures of the κ-carrageenan-electrolyte systems in these solvents were confirmed with an FTIR analysis. The presence of κ-carrageenan did not impede the electrochemical properties of the electrolytes, as confirmed with cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep voltammetry. The incorporation of the gel electrolytes in DSSCs showed that the DMSO system exhibited better solar-cell efficiency compared to the mixed-solvent system.

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... The second generation of PV resembles the use of cadmium telluride (CdTe) and gallium arsenide (GaAs) as thin-film technology media. The third generation of PV can be a dye-sensitized solar cell (DSSC) otherwise known as Grӓtzel cell, perovskite solar cell, quantum dot solar cell, or such emerging technology that can pass the 31-41% efficiency rating standardized using Shockley-Queisser limit [1][2][3]. ...
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Article
The potential of κ-carrageenan derivatives as a green polymer electrolyte has been explored. κ-Carrageenan extracted from marine red algae was reacted with monochloacetic acid to form carboxymethyl κ-carrageenan. The powders were characterized by reflection fourier transform infrared (ATR-FTIR) spectroscopy,13C nuclear magnetic resonance, 1H nuclear magnetic resonance, X-ray diffraction and elemental analysis to confirm the structural, crystallinity and the degrees of substitution. A green polymer electrolyte of κ-carrageenan and carboxymethyl κ-carrageenan were prepared by solution-casting technique. The films were characterized by reflection fourier transform infrared (ATR-FTIR) spectroscopy and electrochemical impedance spectroscopy to determine the chemical interaction and ionic conductivity. The decrease in intensity of hydroxyl, carbonyl, sulfate and ether band confirmed the polymer solvent complex formation. XRD spectra show that chemical modification of κ-carrageenan does not change its amorphous properties. The ionic conductivity was found to increase by three magnitudes higher with the chemical modification of κ-carrageenan. The conductivity achieved was 2.0 × 10− 4 S cm− 1 for carboxymethyl κ-carrageenan in comparison to 5.3 × 10− 7 S cm− 1 for κ-carrageenan.
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The chemical stability of dye-sensitized solar cells (DSSC) determines both the cell performance and the cell life-time. The presence of water in the solar cell from surrounding leakage through the imperfection packaging sealants causes the decrease in life-time of photogenerated electrons on the working electrodes, which induces the occurrence of the dark current to the electrolytes and thus leakage current significantly deteriorated the life-time of the DSSC. Reliable electrolyte additives diminishing the influences of water to the DSSCs degradation process becomes a critical issue in maintaining an acceptable cell life-time.In this work, the effects of four benzimidazole derivatives a–d as the electrolyte additives in the presence of water were comprehensively examined by time-dependent photovoltaic performance of the cells. As a result, open-circuit voltage (Voc), short-circuit current (Jsc), efficiency (η), and fill factor (FF) collected from I–V curves were studied. In addition, electrochemical impedance spectroscopy (EIS) technique was implemented to evaluate the effects of the charge-transfer resistance (Rct) at the interfaces between TiO2/dye/electrolyte. Results showed that the bis-benzimidazole derivative c gives significant improvement in the long-term stability due to the effective protection of the ligands between dye and working electrodes from the attack by environmental water molecules.
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We have studied the influence of electrolytes on the photovoltaic performance of mercurochrome-sensitized nanocrystalline TiO2 solar cells using LiI, LiBr, and tetraalkylammonium iodides as the electrolyte. Short-circuit photocurrent density (Jsc) and open-circuit photovoltage (Voc) depended strongly on the electrolyte. Jsc of 3.42 mA cm−2 and Voc of 0.52 V were obtained for the LiI electrolyte and Jsc of 2.10 mA cm−2 and Voc of 0.86 V were obtained for the Pr4NI electrolyte. This difference in photovoltaic performance was due to the change in the conduction band level of the TiO2 electrode. Large Voc of 0.99 V was obtained for the LiBr electrolyte due to the large energy gap between the conduction band level of TiO2 and the Br/Br2 redox potential. Solar cell performance also depended strongly on organic solvent, suggesting that the physical properties of solvents such as Li ion conductivity and donor number affect photovoltaic performance.
Article
Stable and efficient dye-sensitized solar cells based on water-containing electrolytes are shown. For water contents up to 40%, no decrease in efficiency is seen. The cells are demonstrated to be stable for long periods of continuous illumination.This work lays a foundation for the further development of water-based cells for commercial production.
Carrageenan-Ionic Liquid Composite: Development of Polysaccharide-Based Solid Electrolyte System
  • D H Camacho
  • S J M Tambio
  • M I A Oliveros
D. H. Camacho, S. J. M. Tambio, M. I. A. Oliveros, Carrageenan-Ionic Liquid Composite: Development of Polysaccharide-Based Solid Electrolyte System, The Manila J. of Science, 6 (2011), 8-15
A Novel Biopolymer Gel Electrolyte System for DSSC Applications
  • P Bantang
  • D Camacho
P. Bantang, D. Camacho, A Novel Biopolymer Gel Electrolyte System for DSSC Applications, Proceedings of the DLSU Research Congress, 3, 2015