Papers by Author: Yu Hua Dai

Abstract: Photoelectrodes of mixed polymethylmethacrylate (PMMA) and TiO₂ paste with different ratios were fabricated and studied for improved photovoltaic conversion efficiency in quasi-solid state dye-sensitized solar cells(QS-DSCs). The large pore nanocrystalline TiO₂ films were prepared by the doctor blade method and charicterized by SEM and UV-Vis spectroscopy. SEM images show that large pores have been formed in the TiO₂ films. The transmittance of the films increased with an increase amount of PMMA, while the light-absorption decreased when the films covered by dyes. I-V curves show that a relatively high photovoltaic conversion efficiency of 2.1%~2.26% was achieved when the PMMA/ TiO₂ paste weight ratio was in the range of 1:25~1:35 under AM 1.5 illumination at 100mW/cm².

Abstract: A series of copolymers P(VP-HEMA) composed of hydroxyl ethyl methacrylate (HEMA) and 4-vinyl pyridine (VP) were prepared by a solution copolymerization technique. Based on the copolymer P(VP-HEMA) prepared by the content of VP 50%, the amount of AIBN 3% and the optimized liquid electrolyte, a polymer solution electrolyte with concentration of 9.0% was formed. By addition of 1,4-dibromobutane into the solution, the copolymer gel electrolyte with higher conductivity 6.14mS/cm was prepared. Gelation is caused by the quaterisation between the group of pyridine in P(HEMA-VP) and 1,4-dibromobutane. Based on the copolymer gel electrolyte, a dye-sensitized solar cell was fabricated with short-circuit current of 13.62mA/cm²,open circuit voltage of 0.72V, fill factor of 0.5465 and an overall conversion efficiency of 5.24% under irradiation 100mW/cm² (AM1.5).

Abstract: A series of copolymers P(MMA-NVP) composed of methyl methacrylate (MMA) and N-vinyl pyrrolidone (NVP) were prepared by a solution copolymerization technique. The copolymer could absorb and capture amount of liquid electrolyte within its chain networks structure to form quasi-solid-state electrolyte. The influences of synthesis conditions for copolymers, such as the content of NVP, the amount of initiator 2,2’-azobisisobutyronitrile(AIBN), and the amount of crosslinking agent triethylene glycol dimethacrylate(TEGDMA) on the ionic conductivity of quasi-solid electrolyte were investigated. The highest conductivity of the copolymer gel was 2.17mS/cm at 25°C. Based on the copolymer gel electrolyte, a dye-sensitized solar cell was fabricated with short-circuit current of 12.16mA/ cm², open circuit voltage of 619mV, fill factor of 0.4633 and an overall conversion efficiency of 3.05 % under 100 mW/cm2 irradiation (AM1.5).

Abstract: The dye – sensitized solar cell (DSSC) is an attractive and promising device for solar cell applications that have been intensively investigated worldwide. DSSC consists of a namo TiO2 film of the photo electrode, dye molecules absorbed on the surface of TiO2 film, an electrolyte layer and a Pt counter electrode. Among these, the nanoporous TiO2 film plays an important role because it can adsorb a large amount of dye molecules which provide electrons. Therefore, the TiO2 film affects the cell performance. In this paper, the characteristics of DSSCs with different TiO2 film thicknesses were studied by using electrochemical impedance spectroscopy(EIS). The impedance component attributed to TiO2|electrolyte interface indicated that the small semicircle and low characteristic frequency was essential for high performance DSSC. An optimum overall conversion efficiency( ％) of 5.54% was obtained in the DSSC assembled with the TiO2 film thickness of 8.86μm.