OPTICAL-PROPERTIES AND ELECTROLUMINESCENCE CHARACTERISTICS OF POLYACETYLENE DERIVATIVES DEPENDENT ON SUBSTITUENT AND LAYER STRUCTURE

Intense photoluminescence (PL) is observed in di-substituted polyacety lene derivatives even though solitonic mid-gap absorption is observed upon doping, contrary to non-substituted trans-polyacetylene and mono- substituted polyacetylene in which strong PL is not observed. Intense green and blue electroluminescence (EL) is realized utilizing poly(dip henylacetylene) derivatives and poly(1-alkyl-2-phenylacetylene) deriva tives, respectively. Greenish-blue emission is also observed in poly(1 -chloro-2-phenylacetylene) derivatives. The dependence of wavelength a nd intensity of PL and EL on the molecular structure of substituents i s clarified in detail. The effects of molecular alignment and layer st ructure on the EL characteristics are also discussed. Upon intense lig ht excitation, remarkable spectral narrowing due to stimulated emissio n is also observed in these di-substituted polyacetylene derivatives. (C) 1997 Elsevier Science S.A.