Frabrications of Sb2S3 Quantum Dot and Exfoliated Montmorillonite/Ionic Liquid Composites and their Applications on Dye Sensitized Solar Cells
Date Issued
2015
Date
2015
Author(s)
Ma, Wei-Ling
Abstract
The thesis has two parts. The first one was to farbricate the Sb2S3 quantum dots for quantum dot solid state solar cell. The second part was using the cationically- exofloilated exMMT/ionice liquid mixture to prepare the gel-type electrolyte for dye sensitized solar cells and analyzing their photovoltaic properties. In the first part, we used the chemical bath deposition method to deposit Sb2S3 onto the porous TiO2, which was then characterized by XRD and EDS. By using the Uv-vis spectroscopy, we found that by depositing for longer time, it had the higher absorption of visible light, indicating that there had more Sb2S3 on porous layer. By using SEM and TEM, we could observe its morphology on porous layer and found that Sb2S3 formed as a film onTiO2. The power conversion efficiency (PCE) of as-fabricated QD-ssDSSC was 0.85%. For the second part, our lab had found that the anionically-exfoliated MMT could oxidize I- to I3- and even to I5-. The PCE of the DSSC frabricated by the exMMT gelatinizing ionic liquid could achieve 7.72%. By the same token, the cationically- exfoliated MMT could also oxidize I- to I3-. This master thesis employed the cationically-exfoliated MMT to gelatinize the ionic liquid electrolyte for dye sensitized solar cell. First, we added various I2 molarities ([I2]) into exMMT/PMII mixtures for electrolyte. We found that as [I2] was increased, it would increase [I3-] to enhance to photoelectron recombination, so Voc would decrease. At the same time, because the regeneration rate of dyes also increased, Jsc would increase first and then decrease with increasing the charge recombination. When 4 wt% exMMT was added for gelation, adding 0.2M I2 could achieve the highest efficiency of 7.423±0.008%. On the other hand, if [I2] was fixed at 0.2M and the weight percentage of exMMT in PMII was varied, we found that the Voc increased and the highest PCE of 7.590±0.037% was achieved at 3 wt% exMMT. Because the addition of exMMT also increased the charge recombination rate, we believed that the increase of Voc might be attributed to the decrease of counter electrode redox potential. When the PMII/EMII mixed ionic liquid was used for the electrolyte, we found that as the ratio of EMII was increased, Jsc would increase. It was believed that because the electrolyte viscosity decreased, it would be easier to infiltrate into TiO2 mesoporous layer.
Subjects
quantum dot
ionic liquid
dye-sensitzed solar cell
SDGs
Type
thesis
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