Electric and dielectric properties of some luminescent solar collectors based on phthalocyanines and hematoporphyrin doped PMMA

摘要

The electrical properties: DC-electrical conductivity (sigma_(DC)), AC-electrical conductivity (sigma_(AC)), dielectric permittivity (epsilon') and dielectric loss (epsilon'') for pure polymethylmethacrylate (PMMA) and mixed with phthalocyanine, Ni-phthalocyanine and hematoporphyrin IX chloride laser dyes have been investigated. The conductivity values for all polymer-dye samples are higher than that of the pure PMMA. For all investigated samples, at the constant temperature, the frequency dependence of ((sigma_(Ac)) was found to obey the relation (sigma_(AC)) =A omega~s. The results are discussed according to the correlated barrier hopping CBH mechanism from which the Coulomb well barrier of charge carriers (W_M) was calculated. For the dye-doped samples, the hematoporphyrin IX chloride mixed sample showed the larger value of (W_M) compared with the others. At all frequencies, epsilon' values for doped samples are higher than that of pure one. This is due to a free volume enhancement offered by the large size of the dye molecule. Also, the addition of dyes to PMMA causes an increase in the intensity of the loss peak (epsilon'') accompanied by a shift in its position. The effect of chemical structure of investigated dyes on the electrical properties is discussed.