Abstract: A semiconductive conjugated copolymer comprises at least two chemically different monomer units which, when existing in their individual homopolymer forms, have different semiconductor bandgaps. The proportion of said at least two chemically different monomer units in the copolymer is selected to control the semiconductor bandgap of the copolymer so as to control the optical properties of the copolymer. The copolymer is formed in a manner enabling it to be laid down as a film without substantially affecting the luminescent characteristics of the copolymer and is stable at operational temperature.The semiconductor bandgap may be spatially modulated so as to increase the quantum efficiency of the copolymer when excited to luminesce, to select the wavelength of radiation emitted during luminescence or to select the refractive index of the copolymer.

Abstract: A method is provided for forming in a semiconductive conjugated polymer at least first and second legions having different optical properties. The method comprises: forming a layer of a precursor polymer and permitting the first region to come into contact with a reactant, such as an acid, and heat while permitting the second region to come into contact with a lower concentration of the reactant. The reactant affects the conversion conditions of the precursor polymer in such a way as to control the optical properties of at least the first region so that the optical properties of the first region are different from those of the second region. The precursor polymer may comprise a poly(arylene-1, 2-ethanediyl) polymer, at least some of the ethane groups of which include a modifier group whose susceptibility to elimination is increased in the presence of the reactant.

Abstract: A semiconductive conjugated copolymer comprises at least two chemically different monomer units which, when existing in their individual homopolymer forms, have different semiconductor bandgaps. The proportion of said at least two chemically different monomer units in the copolymer is selected to control the semiconductor bandgap of the copolymer so as to control the optical properties of the copolymer. The copolymer is formed in a manner enabling it to be laid down as a film without substantially affecting the luminescent characteristics of the copolymer and is stable at operational temperature.The semiconductor bandgap may be spatially modulated so as to increase the quantum efficiency of the copolymer when excited to luminesce, to select the wavelength of radiation omitted during luminescence or to select the refractive index of the copolymer.

Abstract: An electroluminescent device includes a semiconductor layer (4) in the form of a thin dense polymer film comprising at least one conjugated polymer, a first contact layer (5) in contact with a first surface of the semiconductor layer, and a second contact layer (3) in contact with a second surface of the semiconductor layer. The polymer film (4) of the semiconductor layer has a sufficiently low concentration of extrinsic charge carriers that on applying an electric field between the first and second contact layers across the semiconductor layer so as to render the second contact layer positive relative to the first contact layer charge carriers are injected into the semiconductor layer and radiation is emitted from the semiconductor layer.

Abstract: A method is provided for forming in a semiconductive conjugated polymer at least first and second regions having different optical properties. The method comprises: forming a layer of a precursor polymer and permitting the first region to come into contact with a reactant, such as an acid, and heat while permitting the second region to come into contact with a lower concentration of the reactant. The reactant affects the conversion conditions of the precursor polymer in such a way as to control the optical properties of at least the first region so that the optical properties of the first region are different from those of the second region.The precursor polymer may comprise a poly(arylene-1,2-ethanediyl) polymer, at least some of the ethane groups of which include a modifier group whose susceptibility to elimination is increased in the presence of the reactant.