Sb2S3量子點及脫層蒙脫石/離子液體複合材料之製程及在染料敏化太陽能電池之應用

Abstract

本論文主要分為兩部分，第一部分製備Sb2S3量子點作為染料之固態量子點電池，第二部份利用陽離子脫層法脫層之蒙脫石/離子液體複合材料作為染料敏化太陽能電池之電解質並探討其光伏性質。 在第一部分中，以化學浴沉積法(CBD) 於多孔性二氧化鈦上沉積Sb2S3，由UV-vis發現當沉積時間越久，對可見光波段有越高的吸收，推測沉積上Sb2S3的量越多 ;並以XRD、EDS鑑定其結構，同時也以SEM、TEM觀察其附著於多孔性二氧化鈦上之形貌，發現Sb2S3以薄膜型態沉積在二氧化鈦表面，沉積時間4hr之Sb2S3固態量子點電池100 mW/cm2下光電轉換效率可達0.85±0.06%。在第二部分中，由於本實驗室曾發現陰離子脫層法脫層之蒙脫石會促進I-氧化成I3-、I5-，且利用陰離子脫層蒙脫石膠化離子液體的電池元件可達到7.72%的效率;而陽離子脫層法脫層之蒙脫石可促進I-氧化成I3-，本實驗將以陽離子脫層之蒙脫石膠化離子液體製備之太陽能電池做比較。首先先以不同體積莫耳濃度的I2添加進exMMT/PMII奈米複合材料作為電解質，當I2量增加時，因會產生I3-搶TiO2上光電子，導致Voc下降，且因染料有regeneration產生，導致Jsc會先上升，後來隨著recombination增加又下降。當添加4 wt% exMMT產生gel的狀態時，以添加0.2M I2的效率最高，在100 mW/cm2下效率可達到7.423±0.008%，因此在添加不同比例exMMT和不同比例PMII/EMII做為電解質溶劑之實驗時I2添加量都固定為0.2M。接著在PMII中添加不同wt% 之exMMT，發現當exMMT比例越高時，其Voc越高，效率最高發生在3 wt% exMMT 為7.590±0.037%，且發現添加exMMT會增加recombination，但可能也使對電極還原電位下降，因此整體Voc會有提升。在以不同比例PMII/EMII作為離子液體電解質溶劑實驗中，發現當EMII比例越高時，其Jsc也會越高，推測是因電解質黏度下降，可更容易滲透進入二氧化鈦孔洞中。

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.