Semiconductivity,optical properties,and EPR spectra of phenothiazine derivatives in the solid state

The optical, EPR, and electrical properties of phenothiazine derivatives have been investigated as a function of R₂ substituents. Diffuse reflectance spectra show a charge transfer complex transition between 600 and 1100 nm. The EPR spectra show the existence of the radical cation with an unpaired electron per molecule; also there can be seen a dependence of the bandwidth on the R₂ substituents. Measurements of electrical conductivity show a semiconductor behavior in the studied temperature range; the values show as well a dependence of conductivity on R₂. The estimation of the drift mobility of charge carriers seems to indicate a hopping mechanism for the charge conduction.