Exciton dissociation in poly-phenylene-vinylene derivative:perylenediimide and hexabenzocoronene derivative:perylenediimide blend systems

Steady state photoconduction both in a phenyl-substituted copolymeric poly-phenylene-vinylene (PhPPV) and in alkylated hexa-peri-hexabenzocoronene (HBC) doped by perylenediimide (PdI) at a broad range of dopant concentrations has been measured and compared to previous results [J. Chem. Phys. 117 (2002) 1395] on PhPPV doped by trinitrofluorenone (TNF). At relatively small concentration (< 10 wt.%), the yield of the photogeneration is almost independent of the system and blend ratio because practically every primary excitation dissociates at a donor-acceptor site and the subsequent escape from the coulombic potential is virtually system-independent. At dopant concentrations >10 wt.%, the yield of that escape process increases by approximately two orders of magnitude explained by both shielding of the pair potential and the onset of percolative electron motion across the acceptor network. (C) 2003 Elsevier Science B.V. All rights reserved.