Accession Number:

ADA282625

Title:

Photogeneration of Charge Carriers in Bilayer Assemblies of Conjugated Rigid-Rod Polymers

Descriptive Note:

Technical rept.

Corporate Author:

ROCHESTER UNIV NY DEPT OF CHEMICAL ENGINEERING

Report Date:

1994-07-08

Pagination or Media Count:

51.0

Abstract:

The quantum yield and the mechanism of photogeneration of charge carriers are investigated in bilayer assemblies consisting of a pi-conjugated rigid-rod polymer layer and a triarylamine doped polycarbonate layer. The electric field dependent quantum efficiency of photocarrier generation, PhiE, in the bilayers containing a series of conjugated polybenzobisazoles was measured by photoinduced discharge and was found to be in the range of 10exp - 3 to 10exp -2 at low fields 10exp 4 Vcm and as high as 0.12 - 0.32 at approx. 10exp 6 Vcm. The PhiE data were qualitatively in accord with Onsagers three-dimensional model for ion-pair dissociation. Transient ps absorption spectroscopy of single layer thin films of the polymers showed that the primary photoexcitations were excitons. However, picosecond photoinduced absorption and photoluminescence experiments on the bilayers revealed photoinduced electron transfer and exciplex formation at the bilayer interface. Thus photocarrier generation on photoexcitation of the conjugated rigid-rod polymers in the bilayer occurs by photoinduced electron transfer, forming intermolecular exciplexes which dissociate efficiently in electric field. This mechanistic picture of charge carrier photogeneration provided a satisfactory account for the observed field dependent quantum yields in the series of bilayer assemblies.

Subject Categories:

  • Polymer Chemistry
  • Electricity and Magnetism
  • Quantum Theory and Relativity
  • Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE