Charge carrier transport in pure and phenylated poly(naphthoylenebenzimidaz
ole) was compared by measurements of transient radiation-induced conductivi
ty. Irradiation with single 100-mus pulses of 55-keV electrons was carried
out in vacuum at room temperature. Contrary to expectations, the phenylatio
n deteriorated the transport properties of a polymer: the delayed radiation
-induced conductivity in phenylated poly(naphthoylenebenzimidazole) was alm
ost 50 times lower than in the initial polymer, with the dispersion paramet
er decreasing from 0.4-0.25 to less than or equal to0.05. As a result, the
drift mobility of charge carriers falls by a few orders of magnitude. The m
echanism of such behavior still remains unclear.