Abstract: An electroluminescent device comprising: a first charge-carrier injecting layer for injecting positive charge carriers and a second charge-carrier injecting layer for injecting negative charge carriers, at least one of the charge-carrier injecting layers being patterned so as to comprise spaced-apart charge-injecting regions; an organic light-emitting layer located between the first and second charge-carrier injecting layers; and an unpatterned conductive polymer layer located between the organic light-emitting layer and the patterned charge-carrier injecting layer, the resistivity of the conductive polymer layer being sufficiently low to allow charge carriers to flow through it from the charge-injecting regions to generate light in the organic light-emitting layer but sufficiently high to resist lateral spreading of charge carriers beyond the charge-injecting regions.

Abstract: Provided is a method for synthesizing a poly(arylene vinylene), which method comprises selecting a vinyl monomer by controlling the ratio of cis isomer to trans isomer in the monomer, and forming the poly(arylene vinylene) from the resulting vinyl monomer, such that the desired cis vinylene to trans vinylene ratio is obtained in the poly(arylene vinylene) product.

Abstract: The invention concerns optically absorptive photonic devices and in particular photovoltaic and photoconductive devices. It is particularly concerned with devices formed from multiple semiconducting layers, e.g., organic semiconducting polymers. Such a device has two central semiconductive layers which have been laminated together so as to form a mixed layer between the first and second semiconductive layers, while retaining at least some of the first and second semiconductive layers on either side of the mixed layer.

Abstract: An organic light-emitting device wherein the cathode (4, 5) comprises a first layer (5) of a conducting material and a second layer (4) of a conductive material having a work function of at most 3.7 eV and wherein the second layer is substantially thinner than the first layer, having a thickness of at most 5 nm.

Abstract: The contrast of an electroluminescent display using an organic EL layer is improved by using a circular polariser in front of the surface. The polariser causes ambient light to be absorbed, while allowing transmission of emitted light and therefore improves the contrast of the display.

Abstract: An electroluminescent device is described which utilizes a “memory effect” which allows a device to be turned on by a turn on voltage and then for the voltage to be reduced without a reduction in the light output. The present electroluminescent device incorporates a semiconductive conjugated polymer layer together with a light dependent voltage regulating layer the conductivity of which varies with light incident thereon from the semiconductive conjugated polymer layer. An electroluminescent device using a semiconductive conjugated polymer layer is relatively simple to manufacture as compared with earlier devices.

Abstract: A method for tailoring the viscosity of a conjugated polymer precursor, the method comprising synthesizing the precursor by a polymerization reaction and, during the polymerization reaction, applying a shear to the reactants of the polymerization reaction so as to define the viscosity of the precursor at a desired value.

Abstract: A display comprises a light modulator defining an array of pixels arranged in rows (2) and columns (3) and addressable to select between at least an opaque state for each pixel and a transparent state for each pixel. The display includes a light emitting device arranged adjacent the light modulator to act as a light source for the display. The light modulator is a passive matrix liquid crystal display device and the light source is an electromumninescent LED. The light source is addressable to emit light from selected regions LER, each region overlapping at least a plurality of rows (2) of the light modulator. In this way, the problem of electrical cross-talk in the display is reduced.

Abstract: An organic electroluminescent device, particularly for use as a display, is disclosed which is driven according to a pulsed mode of operation which allows much higher current densities to be injected into the device. This is achieved by selection of particular pulse durations and duty cycles, and by an improved geometry for the electroluminescent device in which the resistance of anode lines is reduced.

Abstract: A light-emitting cavity device comprising: a pair of mirrors spaced apart to define a resonant cavity; a luminescent layer located in the cavity; and a control layer located in the cavity and controllable to adjust the resonance wavelength of the cavity and thereby spectrally redistribute the energy emitted by the luminescent layer.

Abstract: A light-emissive polymer device comprising: an anode; a cathode; a conjugated light-emissive polymer layer located between the anode and the cathode; and a driver for applying a voltage drive scheme between the anode and the cathode of a pattern having a relatively high voltage portion which causes the polymer layer to emit light and a relatively low voltage portion during which substantially no light is emitted by the polymer layer.

Abstract: A method of making a light emitting device comprises the laminating together of two self-supporting components, at least one of which has a light emitting layer (12) on an inner surface thereof. A first self-supporting component is formed by coating a first substrate (10) with an organic light emissive material (12). A second self-supporting component is formed by coating a second substrate (2) with an organic material which is one of a light emissive material and a charge transport material (8). The two self-supporting components are laminated together such that the organic materials (8, 12) are located between the substrates (2, 10) in the finished device.

Abstract: A method of fabricating an organic electroluminescent display, which includes laminating together a plurality of self-supporting organic light-emitting devices, each of which is capable of functioning separately as an individual device; wherein each of the organic light-emitting devices in the display emits radiation differently from one another in respect of color, pattern and/or direction; and wherein each of the organic light-emitting devices in the display includes a substrate, a first electrode and a second electrode, at least one of which electrodes is at least semi-transparent, and an organic electroluminescent layer between the electrodes.

Abstract: An electroluminescent device includes first and second layers (6, 12) of light emitting semiconductive conjugated polymers with an electrode arrangement (4, 8, 10, 14) for injecting charge carriers into both light emissive layers to cause light to be emitted therefrom. The first and second light emitting layers are in viewing overlap, and the electrode arrangement includes two sets of electrodes (4, 8, 10, 12) which can be operated independently. The first light emissive layer is arranged to emit radiation of a first wavelength when excited and the second light emissive layer is arranged to emit radiation of a second wavelength when excited. The electroluminescent device can thus be operated to cause either radiation of the first wavelength or radiation of the second wavelength or both to be emitted and viewed.

Abstract: An electroluminescent device has at least two active semiconductive conjugated polymer light emitting layers arranged between a cathode and an anode. The layers are arranged so that at least part of at least two layers lie in an emission zone of the device.

Abstract: In an electroluminescent device which comprises a layer of a semiconductive conjugated polymer between positive and negative charge carrier injecting electrodes, a barrier layer is arranged between the layer of semiconductive conjugated polymer and the charge carrier injecting layer for negative charge carriers. The barrier layer protects the layer of semiconductive conjugated polymer from for example mobile ions released by the reactive charge carrier injecting layer. The barrier layer can in some circumstances also itself be light-emissive.

Abstract: A photoresponsive material comprises molecular or polymeric semiconductors in which photogeneration of separated charge carriers proceeds substantially via an intermediate stage of a triplet exciton, where the generation of the triplet exciton may be facilitated by the presence of elements of high atomic number, and in which the generation of separated charges from the intermediate triplet excited states is facilitated by the presence of at least two semiconductive components, one of which is of high electron affinity and able to accept electrons, and the other of which is of low ionisation potential and therefore able to accept positive charge carriers, the difference between the electron affinity of the former and the ionisation potential of the latter being sufficiently low so as to allow the ionisation of a triplet exciton which is present on either of the two aforementioned semiconductive components or on a third component.

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 is provided incorporating an emissive layer comprising a processible polymer matrix such as poly(methylmethacrylate) and a chromophoric component such as an asymmetric stilbene or distyrylbenzene. The chromophoric component is blended with the polymer matrix or covalently attached thereto as a side chain and is selected to emit radiation in the region 400 nm to 500 nm when excited to luminesce.

Abstract: A photodetector device includes a semiconductive conjugated polymer, such as PPV, arranged between first and second electrode layers having different work functions, a bias circuitry connected to apply a bias voltage between the first and second electrode layers, and a sensing circuitry connected to detect a photocurrent flowing between the first and second electrode layers across the polymer layer as a result of radiation incident on the polymer layer while the bias voltage is applied. The bias voltage is selected in relation to the thickness of the polymer layer.