| Summary: | 碩士 === 國立宜蘭大學 === 化學工程與材料工程學系碩士班 === 99 === World wide scientific community have invested much attention in dye sensitized solar cells (DSSCs) with possibilities of high energy conversion efficiency and low fabrication cost. In DSSCs, titanium dioxide (TiO2) photoanode plays an important role. Titanium dioxide (TiO2) is one of promising materials as a nano-porous thin film for working electrode in DSSCs, due to its appropriate energy band gap, dye adsorption ability, and easy preparation.
This thesis was divided to two part, In the first part, a series of pastes with various weight ratios of ethyl cellulose for the application of dye sensitized solar cells (DSSCs). In the second part, a systematic investigation of the influence of mixed-particle TiO2 with various aTiO2 to ST41 ratio (20 nm /160 nm ) toward the DSSCs efficiency. I will discuss the scattering layer effect for the mix-particle TiO2 film.
Part I. The ethyl cellulose is a rheological agent which reduces cracks in the oxide films. For the purpose of DSSCs efficiency study, the porous TiO2 electrodes were prepared by screen printing the TiO2 paste onto FTO substrates followed by thermal annealing. The DSSC made from paste with 5.82 wt% ethyl cellulose demonstrates an energy conversion efficiency of 6.26 % with Jsc of 14.77 mA/cm2, VOC of 0.70 V, and FF of 0.61 under the 100 mW/cm2 illumination. By adding the ethyl cellulose, the photoconversion efficiency of DSSC was enhanced by ~27.5 % over the ethyl cellulose-free DSSC, presumably due to the increase of electron transportation rate.
Part II. The thin titanium dioxide (TiO2) semiconductor layer in addition with different sizes of scattering layer were investigated to fabricate the TiO2 photoanodes for DSSCs. A nano-porous TiO2 thin film electrode for DSSC application was fabricated using a-TiO2 sol coated on a transparent conductive glass with an additional light scattering layer consisting of mixed a-TiO2 and commercial TiO2 ST41 nanoparticles. The overall DSSC efficiency obtained based on this TiO2 electrode is 5.74 % with TiO2 film thickness of 8.2 μm. We have investigated the scattering layer composition as a function of a-TiO2/ST41 weight ratio. It was found that upon increasing the ST41 weight ratio from 1/9 to 2/3, the efficiency increases from 7.16 % to 7.85 %. Further increase of ST41 weight ratio results in the decrease of efficiency. The best efficiency obtained in this work is 7.82 % (Voc= 0.75 V, Jsc = 15.895 mA/cm2, FF = 0.66) from A6S4 (60% a-TiO2 and 40% ST41) cell with TiO2 film thickness of 15.3 μm, which is 32 % enhancement compared with the TiO2 film without scattering-layered
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