Depolarizing energy transfer in photoluminescent polymer blends

The occurrence of a depolarizing polarizing energy transfer effect is demon strated in uniaxially oriented polymer blend films. These blends are based on ultra-high molecular weight polyethylene as the matrix polymer, and addi tionally comprise 1,4-bis(2-ethylhexyloxy)phenylethynyl) benzene (EHO-BPB) as a sensitizer, and either a regioregular HT sexi(3-n-octylthiophene) (6OT ) or 7-(dimethylamino)-4-trifluoromethyl) coumarin (C152) as emitter. The E HO-BPB sensitizer molecules are highly oriented in tensile-deformed blend f ilms, and, thus, cause a highly anisotropic, i.e. linearly polarized optica l absorption. The absorbed energy is, subsequently, transferred to the emit ter molecules, which are essentially unoriented and, consequently, emit unp olarized light. (C) 2000 Elsevier Science S.A. All rights reserved.