Intrinsic photoconduction and photoemission in polyethylene

Abstract

Intrinsic photoemission and photoconduction of polyethylene in the photon energy range 7<E<14 eV have been experimentally investigated. Both phenomena are parabolic in E with the same threshold energy EG=8.8 eV. The main features of a model that accounts for the observations are: (a) EG is the intrinsic electron-hole band gap. (b) Strong absorption for 7.6<E<8.8 eV is due to exciton creation. (c) The bottom of the conduction band lies an energy A above the vacuum level, where 0<A<1.2 eV. (d) The photocurrents are due to rapid motion of carriers through a short distance approximately=10 nm along individual polyethylene chains. (e) The carriers subsequently travel through the polyethylene with a very low mobility.