Ki-Ju Kim

Quasi-Solid State Dye Sensitized Solar Cell Based on Poly (Acrylonitrile-co-Methacrylonitrile)-Silica Gel Electrolyte

The solid state dye-sensitized solar cells (DSSCs) are shown low conversion efficiencies as compare to liquid based DSSCs due to incomplete wetting of photoelectrode by solid electrolyte and poor contact of the solid state materials with the surface of dye coated TiO 2 surface. In current work, poly (acrylonitrile-co-methacrylonitrile)/silica based gel electrolytes have been successfully employed to fabricate quasi-solid state DSSC with the overall energy conversion efficiency of 3.0%, open-circuit voltage of 0.784 V and short circuit current of 7.33 mA/cm2 at 1 sun irradiance (100 mW/cm2). The introduction of silica filler into the copolymer [poly(acrylonitrile-co-methacrylonitrile)] matrix reduces the crystallinity of the copolymer, which increases the mobility of iodide/triiodide couple. The optimized experimental conditions such as gelation time, composition of SiO2 nanoparticles and thickness of TiO2 have been discussed in detail at this work

Charge storage and transfer in dye-sensitized solar cells: a study by electrochemical impedance spectroscopy

AC impedance measurement was found as an efficient tool to elucidate the charge storage and transfer in dye-sensitized solar cells. The imaginary impedance of the apparent space charge region at the dye adsorbed TiO/sub 2//electrolyte interface was inversely dependent on the density of photoexcited electrons. For a given TiO/sub 2/ material, the thicker the thickness of the substrate, the higher the charge storage and the slower the charge transfer of the resulting DSC. Accordingly, the existence of an optimized thickness of TiO/sub 2/ substrate is inherent for the highest overall conversion efficiency of a DSC fabricated with a given TiO/sub 2/ material. The combination of the charge storage or the density of photoexcited electrons in the porous TiO/sub 2/ film and the prompt charge transfer between it and TiO/sub 2//TCO glass interface was worthwhile to note for improvement on the overall conversion efficiency of DSC.

Module construction of dye-sensitized solar cells by using chemical etching

Module construction of dye-sensitized solar cells (dsscs) by using chemical etching was found as a simple process to characterize and optimize the size of unit cell in terms of photovoltaic performance of the resulting module. This method was also a simple and promising process to enlarge dssc size and commercialize dssc module. Under high intensity irradiation, the deleterious effect of internal resistance in the unit cell of dssc module was found to become significant on the photovoltaic performance of the system. Meanwhile, high active area dssc module that is always accompanied by the low external resistance gives rise to the high photovoltaic performance of the system under low intensity illumination. Accordingly, optimization of the size of unit cell is worthwhile to note for the optimum performance of resulting dssc module under a particular illumination source.

Optimization of TiO/sub 2/ substrate for dye-sensitized solar cells

The effect of pre-thermal treatment on anatase TiO/sub 2/ with high specific surface area (ca. 334 m/sup 2//g, HK) was investigated for dye-sensitized solar cell (DSC). The optimized substrate was observed on the HK pre-calcined at 450/spl deg/C (HK-450) in terms of morphological feature, crystallinity, surface area, and photocurrent density. A DSC fabricated with HK-450 exhibited the high photovoltaic performance with significantly improved short-circuit current. This was attributed to the superior morphological features of HK-450, causing the high adsorption of dye and high photocurrent density. The optimization between the morphological feature, crystallinity, specific surface area and the photocurrent density of TiO/sub 2/ substrate was found to give rise to the improved overall conversion efficiency of DSC.