Electrical conduction and dielectric properties of poly(methyl methacrylate)/perylene solar concentrators

Poly(methyl methacrylate) doped with fluorescent perylene dye was prepared by both radical polymerization of methyl methacrylate and solvent casting from polymer solutions. The samples were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, electrical conductivity, and dielectric properties. Both conductivity and dielectric properties were measured in the temperature range 303-433 K and the frequency range 10(3) to 5 x 10(6) Hz. The results show that the direct-current electrical conductivity increased by increasing dye content in solvent-cast samples, whereas it decreased radically polymerized samples. The results of alternating-current conductivity suggest electron hopping between filled and empty localized states. The study of dielectric properties showed two relaxation peaks corresponding to the dipole segmental and dipole group losses. Explanations based on the polymer free.,volume and acid-base interactions were proposed to examine the influence of the sample preparation and perylene dye concentration on the glass-transition temperature and dielectric relaxation of the samples. The obtained results recommend the thermal and molecular stability of luminescent solar concentrator (LSC) matrices prepared by radical polymerization over those prepared by solvent casting. (C) 2003 Wiley Periodicals, Inc.