The Construction Of Dye-Sensitized Solar Cells Based On Solid-State Electrolytes And Their Photovoltaic Performance

Dye-sensitized solar cells (DSSCs) have been widely considered as potential inexpensive alternatives to conventional p-n junction photovoltaic devices over the past decades. A typical DSSC consists of a mesoporous nanocrystalline TiO2 film covered by a monolayer of dye molecules, redox electrolyte, and counter electrode. However, the disadvantages of using liquid electrolytes are solvent evaporation, leakage of electrolyte and high-temperature instability. Therefore, many efforts have been made to substitute the liquid electrolytes with solid-state DSSCs.The first electrolytes were made by PEO, LiI, I2 as solute, TiO2 as nanofiller and acetonitrile as solvent. We discussed the effect of nano TiO2 content on the conductivity of the solid-state polymer electrolyte. Under optimized, the ionic conductivity of the electrolyte reached to 3.1×10-5Scm-1. The solid-state TiO2 cell fabricated with this electrolyte achieved a conversion efficiency of 2.49% under 100 mW/cm2 radiation.The second electrolytes were made by PEO, Oligo-PEG, LiI and I2 as solute, acetonitrile as solvent. We discuss the effect of Oligo-PEG content on the conductivity of the solid-state polymer electrolyte and the photovoltaic performance of DSSC. Finally, the ionic conductivity of the electrolyte reached to 7.1×10-5 S cm-1 and the conversion efficiency of DSSC achieved 3.94%.The third electrolyte was consisted of PEO/oligo-PEG/TiO2/LiI/I2. The ionic conductivity of the electrolyte was evidenced to possess high ionic conductivity and excellent penetration by introducing TiO2 particles as nanofillers into PEO/PEG system. The solid-state DSSCS fabricated with this electrolyte achieved a high conversion efficiency of 5.08%.A novel solid-state hierarchically-structured ZnO dye-sensitized solar cell was assembled by using TiO2 as filler in polyethylene oxide (PEO)/polyethylene glycol (PEG) electrolytes and ZnO nanocrystalline aggregates as photoanode film. Under optimized composite polyelectrolyte containing PEO/oligo-PEG/TiO2/LiI/I2 the photovoltaic performance of the solid-state ZnO DSCs was significantly better, with an overall conversion efficiency (η) of 1.8% under irradiation of 100 mW cm-2, which was higher than those of the cells with PEO/TiO2/LiI/I2 (η=1.1%) or PEO/oligo-PEG/LiI/I2 electrolyte (η=1.5%). Further, the hierarchically-structured ZnO-based cell showed a higherηvalue of 2.0% under 60 mW cm-2 radiation. The morphologies, ionic conductivity of three different composite electrolytes and their performance to the DSCs were also studied by FESEM,Ⅰ-Ⅴdata, IPCE and EIS.