Investigation of photoinduced change of dielectric and electrical properties of indium (III) phthalocyanine and fullerene doped nematic liquid crystal

Abstract

In this work, we have studied photoinduced dielectric and electrical properties of E63 nematic liquid crystal (E63-LC) materials doped with indium (III) metallo phthalocyanine (In-MPc) and fullerene (C60) in dark and under UV illumination. Doping concentration of In-MPc in E63-LC was chosen to be 5wt%, whereas a trace amount of C60 was used in investigated samples. Real and imaginary parts of dielectric permittivity were investigated in the frequency range of 100Hz–10MHz by using dielectric spectroscopy technique (DST). It was observed that doping agents and UV illumination enhanced the real part of dielectric permittivity at low frequencies, which was thought to originate from photoinduced charge transfer between In-MPc and C60 caused by extra dipole strength in LC medium. In addition to that, critical frequency (fc) and relaxation time (τ) were obtained and analyzed for all investigated samples. Photoelectrical characteristics of hybrid LC structures were carried out by current–voltage measurements. A major increase in electrical conductivity was observed in In-MPc and C60 doped LC structures under UV irradiation.