Abstract
The origin of relaxed exciton formation and its effect on photocarrier generation were examined for a typical donor-acceptor (DA)-type polymer, poly{[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl} (PCDTBT), with a focus on the two unique photoabsorption bands that originate from charge-transfer (CT) and main-chain (MC) excitations, respectively. The results of electroabsorption measurements showed that the CT excitation spatially localizes more than the MC excitation, which plays a crucial role for the relaxed exciton formation. The photocarrier generation characteristics are discussed in terms of the spatial localization of the CT and MC excitations.
