Study On The Fabrication And Performance Of Low-cost Dye-sensitized Solar Cells

The low-cost, abundant, and green photoelectric conversion has always drawn much attention. Dye-sensitized solar cell (DSSC) is one of the third generation thin film solar cells, which is composed of a photoanode electrode, electrolyte, and a counter electrode (CE). Platinum (Pt) is usually used as catalyst for CE. However, the use of noble Pt increases the production cost of DSSC and limites its large-scale production. Carbon materials are abundant, low-cost materials with high catalytic activity, and thus they are expected to replace the Pt. However, the poor adhesion between the carbon material and the conductive substrate (FTO) has a negative effect on the stability of CE and DSSC. Furthermore, the traditional "sandwich" type DSSC consists of two FTO substrates which account for50%of the cost. Therefore, it is necessary to replace or reduce the amount of FTO usage to greatly reduce the cost of DSSC. In this paper, we introudced an organic binder to improve the adhesion between the carbon material and the FTO substrate. We also designed and fabricatied DSSC with only one FTO substrate.Carbon counter electrodes (Cd-CC) with excellent adhesion were successfully fabricated by using conductive carbon paste (CC) as the binder and color black (Cd) as the catalyst. We studied their catalytic activity as CE for DSSC. Cd-CC possesses both a good conductivity and a high catalyic activity. The DSSC based on Cd-CC yielded an energy conversion efficiency of6.69%, and the efficiency remain unchanged after600h light soaking. In addition, we found that this method is also suitable to other carbon materials and metal carbide materials of CEs.We replaced FTO by CC using its high electrical conductivity to fabricate a new DSSC structure which was called L-DSSC. The L-DSSC used only one piece of FTO substrate and one piece of glass. We also optimized the spacer layer and the carbon electrode of L-DSSC. When the TiO2nanoparticles with size of25nm was used for spacer layer, the L-DSSC got the highest photocurrent among other devices. We found that adding catalyst, loading Pt, and high sintering temperature were beneficial for improving the catalytic activity of the carbon CEs. As a result, the conversion efficiencies of the devices increased from2.17%to6.98%.We fabricated a monolithic dye-sensitized solar cell (M-DSSC) using an all screen-printing process. The M-DSSC only needs one conductive substrate. We optimized the particle size and thickness of spacer layer, amount of graphite and PVDF in the carbon layer using devices with active area of0.4cm2. The results showed that the M-DSSC yielded the highest efficiency of8.53%when the mass ratio of ZrO2/TiO2, the film thickness, and the amount of PVDF reached to6:1,3.5μm, and20%, respectively. We also studied the effect of active layer, electrolyte and configuration on the large-scale M-DSSC. The results showed that narrowing the width of photoanode can improve the photocurrent. The efficiencies of M-DSSC using different electrolytes (acetonitrile, MPN, ionic liquid, quasi solid) reached5.79%,4.96%,3.06%, and4.16%, respectively. In addition, the M-DSSC had a good long term stability after2000h test.