PHOTOCONDUCTIVITY OF DOPED POLY(METHYLPHENYLSILANE)

The photocurrent generated by a laser pulse is measured in solid films prepared from poly(methylphenylsilane) (PMPSi) molecularly doped with electron acceptors of various reduction potentials. The doping increased the efficiency of the charge carrier photogeneration but decreased the hole drift mobility measured by the time-of-flight technique. The mobility decreased with the increasing concentration of the dopants. The decrease was most pronounced with phenanthrenequinone, the oxidation potential of which was lower than that of PMPSi. The effect of the other dopants depended on the dipole moment of the molecule. The doping of PMPSi with chloranil, an electron acceptor with zero molecular dipole moment, entailed a slight mobility increase. Models based on hopping through a manifold of states with superimposed energetic and positional disorder and on multiple trapping have been used to describe the charge carrier transport in doped PMPSi.