Microwave-assisted Pulverization of Perylene Pigment and Fabrication of Pigment-Sensitized Mesoporous TiO₂ Solar Cells

Abstract

3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA), which is formed aggregate having over 1 μm of diameter, was dispersed in DMF by microwave (MW) irradiation. Dynamic light scattering method showed that the size of most dispersed perylene particles was 7.5 ± 1 nm, whereas HPLC measurements suggested the presence of a little amount of monomeric perylene molecules. In IR spectra, the C = O stretching band and C-O-H bending vibration band of nano-sized perylene was different from PTCDA and 3,4,9,10-perylenetetracarboxylic acid (PTCA) , suggesting that hydrolysis was occurred in one side of carboxylic dianhydride. In absorption spectrum of the dispersed perylene particle, characteristic vibration structure of the perylene was observed and the absorption bands were shifted at lower energy compared to that of PTCA. In diffuse reflection measurements, nano-sized perylene and PTCA on TiO₂ indicated similar spectra respectively and also on ZnO. Conversion efficiency of the solar cell fabricated by immersing mesoporous TiO₂ electrodes in DMF containing the above-mentioned nano-sized partially hydrolyzed perylene pigment was about 0.13% irrespective of the TiO₂ electrode thickness.