Abstract: A device including semiconductor nanocrystals and a layer comprising a doped organic material disposed over the substrate and in electrical connection with at least one semiconductor nanocrystals is disclosed. Methods for making the device and for improving the efficiency of a device are also disclosed.

Abstract: A multiple color imaging device such as a beam index CRT (FIG. 3a/b), with red, green and blue phosphor stripes arranged in triplets each defining one color image pixel in the line scan direction having at least the red and green phosphor stripes coated with an electrically insulating barrier layer 38 on which is formed a thin layer 39 of blue emitting phosphor. In color display mode the beam energy is sufficient to penetrate the barrier layer and excite the principal stripe phosphor to give the desired color emission but also excites the blue phosphor, blue emissions being perceived at lower luminance than the red and not detrimental to perceived color purity. In monochrome mode the beam energy is reduced to excite only the blue phosphor. As each stripe is able to emit blue when excited the image resolution for monochrome is increased from color triplet dimensions to individual stripe dimensions or better.

Abstract: A cathodoluminescent display device, for example a low-voltage vacuum fluorescent display device, has a source of low-voltage electrons and cathodoluminescent layer for excitation by the low-velocity electrons which comprises particles of phosphor material, for example a sulphide, selenide, telluride or oxy-sulphide phosphor, thar are treated to increase their surface conductivities by, for example, deposition of a surface coating comprising conductive or semi-conductive material.