The Materials and Process Study for Dye-sensitized Solar Cells.

• Main Authors: Hsiou-Hsuan Wang, 王修璇
• Other Authors: Chaohin Su
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/crvyfb

博士 === 國立臺北科技大學 === 有機高分子研究所 === 101 === The purpose of this thesis is to investigate the optimum process condition for the fabrication of working electrode using hard transparent conductive glass and flexible plastic substrate for dye sensitized solar cells (DSSCs). In the first part of this thesis, ethyl cellulose (EC)-based TiO2 pastes were prepared in order to fabricate flat and crack-free TiO2 films employing screen-printing technique. Pure anatase TiO2 was synthesized via hydrothermal process using titanium (IV) n-butoxide as Ti-precursor and peptized by acetic acid. The as-prepared TiO2 sol was employed for making a series of pastes with various weight ratios of ethyl cellulose which was used to prepare the TiO2 electrode using screen-printing technique. The printed TiO2 electrode was observed under the micro-scale condition which exhibited a porous and crack-free structure. The DSSCs fabricated using the paste with 5.82 wt % of EC demonstrated a high energy conversion efficiency of 7. 64% with Jsc = 15.07 mA/cm2, VOC = 0.75 V, and FF = 0.68 under the AM 1.5 with an illumination of 100 mW/cm2. In addition, the dual-function scattering layer made of submicron anatase TiO2 was applied on top of the active layer to increase light harvesting efficiency in DSSCs. The optimized photoconversion efficiency obtained using 11 ?m thick TiO2 active layer and 3 ?m thick TiO2 scattering layer was 9.75%, which was 19% enhancement compared to the DSSCs efficiency without scattering layer. Finally, the counter electrode was made by thermal decomposition of screen-printed dihydrogen hexachloroplatinate (IV) hexahydrate (H2PtCl6, a Pt precursor) on FTO glass. The formation of Pt nanoparticles on FTO showed the enhancement of DSSCs efficiency. The homogeneous dispersion of Pt particles on FTO can be achieved by incorporation of graphene into the Pt precursor solution. The graphene-Pt electrode showed the excellent DSSCs photoconversion efficiency up to 9.56%. The second part of this thesis was mainly focused on the flexible plastic based DSSCs. ITO-PET was chosen as the flexible plastic substrate for working electrode and Pt as counter electrode. Three steps towards the full flexible DSSCs assembling were performed as follows: (1) The preparation of less-crack flexible TiO2 electrode using low temperature sintering TiO2 paste on ITO-PET followed by mechanical compression in order to increase the adhesion between TiO2 and ITO-PET. In this stage, the semi-flexible DSSCs device was made from ITO-PET based TiO2 electrode and FTO based Pt counter electrode. The best efficiency obtained was 5.00%. (2) The demonstration of low temperature process for counter electrode fabrication by spin-coating H2PtCl6 solution on ITO-PET. In this stage, the semi-flexible DSSCs device was made from FTO based TiO2 electrode and ITO-PET based Pt counter electrode. The best efficiency obtained under this condition was 6.91%. (3) To modify the sealing process, including the electrolyte injecting procedure in order to improve the leakage problem of flexible DSSCs as well as the device fill factor and photoconversion efficiency. In this stage, the full flexible device was made from ITO-PET based TiO2 electrode and ITO-PET based Pt counter electrode. The best efficiency of 4.06% can be achieved in this work.