Water-soluble CMY primary color electrochromic polymers: Design, Synthesis and Full Color Control

The next generation of electrochromic materials are required to be rich in color rendering, excellent processability and environmental protection. Soluble electrochromic polymer (ECP) can fulfill these requirements. However, a more...

Method for the numerical evaluation of the color rendering quality of matrix photodetectors

To objectively evaluate the color image of an architectural object when changing its spectral quality and luminance in lighting, it is necessary to ensure its accurate fixation. The measurement of the color coordinates of an object provides the fully capture of its appearance, but this does not allow to get an adequate evaluation of the visual impression without visualizing the lighting scene. This requires a thorough procedure of reproducing the same color coordinates for each point of the image and the object with the same angular coordinates. In this work, an attempt is made to develop a numerical criterion for evaluating the quality of color rendering of the camera as a fixer of color visual impression of the selected scene. The development of a numerical detailed method for evaluation of the quality of color rendering of cameras will allow capturing more reliably such a subjective concept as the correspondence of the visual impression of the real scene and the image file of this scene. The digital format, which contains information about the object, avoids the problems associated with aging of the image. The proposed method of developing ways to numerically evaluate color distortion in photography is considered on the example of digital cameras Nikon D300s, Sony DSC-H5. The described approach for the case of known spectral characteristics allows to unambiguously link the calculated reaction of the camera with the chromaticity coordinates of spectrally pure colors. Modern methods of evaluating the quality of light sources (IES TM-30-15) allow evaluation of the direction of the shift. The proposed indicator – graph E (λi) numerically characterizes the difference between the reaction of the camera and the reaction of the human eye and does not give an idea in which direction there is a difference, conditionally red or blue image compared to the natural scene, but is the simplest and most understandable to the untrained user. It is shown that with an accuracy of measuring spectral characteristics of 1% for the considered example with Nikon D300s, this indicator at different wavelengths is calculated with an uncertainty of not more than 0.002.

Low-Dimensional CsPbBr3@CoBr2 Super-Nanowire Structure for Perovskite/PMMA Composite with Highly Blue Emissive Performance

In this study, low-dimensional CsPbBr3@CoBr2 super-nanowire (SNW) structures were synthesized via a one-pot heating strategy for highly blue emissions. By introducing CoBr2 to CsPbBr3 precursors, the shape of perovskite nanocrystals was changed from cuboids to a super-nanowire structure, as revealed through a transmission electron microscope. SNWs were formed from stacked segments of nano-plates (lateral dimension of 10–12 nm and thickness of ~2.5 nm) with lengths of several microns. The fabricated sample absorbs light at a wavelength of <450 nm, and it is emitted at a wavelength of 475 nm. It also has a radiant flux conversion efficiency of up to 85% when stimulated by a 430 nm LED light source. The average decay time of up to 80 µs indicates that they effectively prevent the recombination of electron–hole pair. The optical performance still remains over 65% when the ambient temperature is up to 120 °C compared with that under room temperature. The excellent color purity, optical quantum efficiency, long carrier lifetime, and thermal stability make CsPbBr3@CoBr2 SNWs highly promising for a range of photolumicescence applications, such as a high color rendering index lighting and transparent blue emissive screen.

Compatibility of Photoluminescence Properties in ScPO4:Eu3+, Tb3+ Phosphor for White Light Emitting Diodes

ScPO4:Eu3+, Tb3+ phosphors with tuned emission color were prepared through high temperature solid-state reaction. The structure, morphology and photoluminescence properties of the title samples were collected by XRD, SEM and fluorescence spectrophotometer, respectively. Co-doping Eu3+ and Tb3+ in ScPO4 does not change the body-centered tetragonal structure of the host. And the morphology remains essentially unchanged except for slight agglomeration. Changing the ratio of Tb3+/Eu3+, the tuned emission can be achieved, the color could be adjusted from green through yellow to orange-red. The ScPO4:0.03Tb3+, 0.03Eu3+ phosphor with high thermal stability as the single matrix phosphor can be suitable for the NUV-pumped white LED. The white LED with a color rendering index of 86.5 and a correlated color temperature of 3470 K has been generated by packaging BAM:Eu2+ with ScPO4:0.03Tb3+, 0.03Eu3+ on an NUV-InGaN chip.