INTRINSIC PHOTOCONDUCTION IN PPV-TYPE CONJUGATED POLYMERS

Steady state photoconduction experiments have been performed on thin f ilms of derivatives of polyphenylenevinylene contacted in sandwich con figuration. The use of a silicon monoxide blocking layer allows the se paration of intrinsic from extrinsic photocurrents. Intrinsic photogen eration increases with electric field, temperature, and photon energy in agreement with the 3D version of Onsager's theory of geminate pair dissociation adapted to energetically random hopping systems. The ther malization distance, which determines the escape rate, increases with the effective conjugation length of the chain segments. The average en ergy required to dissociate a confined on-chain excitation is 0.4 eV.