Spectral, luminescent and electro-optical properties of poly(9,9-dioctylfluorene), containing small quantity (1-2 mol%) of 2,1,3-benzothiadiazole comonomer units, obtained by means of either Suzuki or Yamamoto polycondensation reactions were studied and compared. The difference of luminescent properties of the two copolymers with nearly identical chemical compositions was explained by different molecular structure of their macromolecules. The films of Yamamoto type copolymer, containing, obviously, microblock sequences of 2,1,3-benzothiadiazole units, exhibit a nearly white electroluminescence (CIE x=0.276, y=0.274) with a high brightness (3747 cd/m(2) at 10V), while the films of Suzuki type copolymer with randomly distributed isolated 2,1,3-benzothiadiazole fragments -green electroluminescence. (C) 2015 Elsevier B.V. All rights reserved.