Application of Polymerizable Ionic Liquid and Its Carbon Nano- tube Composites on Electrolytes for Dye-sensitized Solar Cells
Date Issued
2010
Date
2010
Author(s)
Lin, Pei-Yi
Abstract
This research mainly focused on the fabrication and applications of new type ionic liquid polymers and their carbon nanotube composites on dye sensitized solar cell. There are two major parts in this research. For the first part, we synthesized two kinds of ionic liquid monomer carrying acrylic functional group , 1-methyl-3- [2-[(1-oxo-2-propenyl) oxy]-ethyl]- imidazolium iodide (DIL) and 1-methyl-3- [2-[(1-oxo-2-propenyl) oxy]-ethyl]- benzimidazolium iodide (BDIL), and polymerized them by atom transfer radical polymerization, and then used the brominated carbon nanotube to initiate polymerization under the same condition. All the nano-composites were characterized by high-resolution TEM、x-ray photoelectron spectroscopic and thermo-gravimetric analyzer. For the second part, we added different weight percentage of the nano-composite into ionic liquid electrolyte system for investigating the DSSC performance. Besides, we also used the polymerized ionic liquids to prepare the gel-type electrolyte system for the DSSC.
In the first part of the research, both ionic liquid monomers were successfully synthesized and characterized. For the DIL system, the molecular weight estimated from NMR for pure polymer (PDIL) was similar to that estimated from TGA for MWNT-PDIL nano-composite. But for the BDIL system, the molecular weight estimated from NMR for pure polymer (PDIL) was tenfold of that from TGA for MWNT-BDIL nano-composite. It is due to the fact that BDIL was adsorbed on carbon nanotube by π－π stacking resulting from its strong resonance structures. By directly mixing the untreated cabon nanotube with BDIL at room temperature, we found that the BDIL monomer also adsorbed on carbon nanotube in mono-layer on the basis of the TGA data and the simulation result for the resuitng MWNT(untreated)-BDIL nano-composite. All kinds of nano-composites were able to homogeneously disperse in PMII.
In the second part, the photon to electron power conversion efficiency of DSSCs with PMII ionic liquid electrolyte system was 5.00%.When adding the proper amouts of different nano-composites into ionic liquid electrolyte system, the efficiency were raised to 5.59%、5.09% and 5.44% for 0.05wt% MWNT-PDIL、0.5wt% MWNT-BDIL and 0.05wt% MWNT(untreated) -BDIL, respectivily. The higher efficiency mainly resulted from the higher photo current, implying that the carbon nanotube could enhance the charge transfer.
For the PBDIL-base gel electrolyte system, the high Tg of PBDIL impeded the ion diffusion leading to poor photovoltaic performance. For the PDIL-base system which has lower Tg than that of PBDIL, the power efficiency was 1.16%. On the other hand, adding nano-composite into the PDIL-base system further increased the photo current, implying that carbon nanotube provided a short path for charge transfer. The addition of 0.5wt% MWNT(untreated)-BDIL provided the best performance and the efficiency of fabricated DSSC could reach to 3.55%.
Subjects
dye-sensitized solar cell
ionic liquid
polymer-carbon nanotube composite
gel-type electrolyte
atom transfer radical polymerization
SDGs
Type
thesis
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