Chinese chemists have received universal pixel based on electrofluorination materials, which depending on the applied voltage is shining blue, red and green. Scientists have constructed a 24-pixel display and portrayed the letters R, G, B, however, the color change occurred in five seconds — too slow by the standards of modern displays. Article published in the journal Advanced Materials.
As You read this text, the pixels on the screen emit light in accordance with the RGB scheme, in which pixel color is determined by the intensity of the three subpixels of red, green and blue colors. This approach is widely used, although ineffective in the pixel is still a lot of empty space. However, scientists seek to overcome the sub-pixel barrier for reducing the graininess of the picture and enhance the image quality. One such approach — a universal pixel that is able to emit each primary color independently. Three years ago the American scientists have presented the technology of getting universal pixel on the basis of liquid crystals — the color can be controlled by electric voltage due to the plasmon resonance on the surface.
Electroplankton materials — aromatic organic molecules or conjugated polymers, which have different glow in oxidized and reduced form. Accordingly, the change in this shape is due to the application of electricity need a building. Still most of these materials use an electrical current to enable or quench the fluorescence, and for the transition between the two colors. To polymer or organic molecule with three fluorescent centers is difficult, and therefore a possible solution — a combination of two fluorescent materials. A few years ago a device with electroplankton polymers already did, but get rid of sub-pixel technology did not work.
A group of chemists under the leadership of Sean Xiao-an Zhang (Sean Xiao-An Zhang) from Jilin University received the first sample of universal pixel based on electrofluorination material with the three main colors. To circumvent the problem of sub-pixel technology, scientists have chosen the following criteria: each pixel must have three States (one color is lit, the other two not), and this should not be an overlap of the spectra.
To avoid unnecessary interaction between the materials, the researchers separately applied layers of red-green and blue material. For the green-red pair they chose green fluorescein with benzoquinones (elektrooniline) as acceptor of the proton and the red derivative of rhodamine with phenylendiamine (Electronista) as a donor of the proton. These pairs of luminous matter have a large quantum yield (fluorescence efficiency) and the color purity of the emission. To check the absence of interference of fluorescence of these materials, the researchers took fluorescence spectra at different electrical voltage. At a voltage of 1.2 volts was observed a clear peak of emission at 585 nm (red color), and when a reverse voltage is 1.2 volt peak was at 535 nanometers (green).