Depolarizing energy transfer in photoluminescent polymer blends

The occurrence of a depolarizing polarizing energy transfer effect is demonstrated in uniaxially oriented polymer blend films. These blends are based on ultra-high molecular weight polyethylene as the matrix polymer, and additionally 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 EHO-BPB sensitizer molecules are highly oriented in tensile-deformed blend films, and, thus, cause a highly anisotropic, i.e. linearly polarized optical absorption. The absorbed energy is, subsequently, transferred to the emitter molecules, which are essentially unoriented and, consequently, emit unpolarized light. (C) 2000 Elsevier Science S.A. All rights reserved.