VISUAL EFFECTS OF OBJECTS UNDER METAMERISM WITH MULTI-SPECTRAL LIGHT SOURCE

This study attempts to simulate the metamerism colour, and the guava was used as the target object. We design four sets of metamers with a correlated colour temperature of 4000K and an illuminance of 750lux. The light source was simulated in the LED cube. The subjects with convenience sampling observed the visual effects, including look delicious, colourful, and colour rendering of guava under metamerism, then analysed its relationship with CRI and CQS. The results showed that colour rendering and visual effects are not a positive relationship, and the effect of CQS is closer to the visual effects of the subjects. The results of this study can be used as a reference for light source lighting designers as a basis for improving lighting conditions. In the future, we can collect databases for the different objects with an optimized multi-spectral light source.

Mn4+ Activated Deep Red Emitting Perovskite Type Phosphors for Horticulture Lighting

Red emitting Mn4+ doped oxides are a promising class of materials to improve the colour rendering and luminous efficacy of phosphor-converted light-emitting diodes (pcLEDs). For pcLEDs, the optical properties are crucial w.r.t commercial acceptance. In this work, luminescence spectra and decay curves of Sr2YNbO6, Sr2YTaO6 and Sr2LaNbO6 have been recorded, other Mn4+ doped phosphors show that quenching occurs through thermally activated crossover between the 4T2 excited state and 4A2 ground state. The quenching temperature can be optimized by designing the host lattice in which Mn4+ has a high 4T2 state energy. The main target is to study the influence of the above-mentioned host materials on the emission spectra, PL quenching, and quantum yield of the deep red Mn4+ ion. The present study provides detailed insights into temperature and concentration quenching of Mn4+ emission and can be used to realize superior narrow-band red Mn4+ phosphors for horticultural lighting.

The Impact of LED Colour Rendering on Reaction Time of Human Eyes in Tunnel Interior Zone

The long reaction time of human eyes will increase the probability of traffic accidents in tunnels which can be reduced by improving lighting conditions. In recent years, light-emitting diodes (LEDs) have replaced the traditional lighting source in a tunnel. Colour rendering index 2012 (CRI2012, a colour rendering evaluation index) is the most suitable evaluation method for colour rendering of LEDs. In order to study the impact of colour rendering of LEDs on the reaction time of human eyes, a driving simulation environment was designed. First, three CCTs (correlated colour temperatures), four CRI2012s, and eight colours of targets were assessed using mesopic photometry model MES-2. The calculation results indicated that the contrast of targets had a positive correlation with CRI2012 and had a negative correlation with CCT. Then, reaction time experiment was conducted in simulated tunnel environments. There are 30 observers who participated. The results show that the LEDs with higher CRI2012 and lower CCT in tunnel is conducive to reducing the reaction time of human eyes. High CRI2012 enables drivers to accurately and quickly identify colours. This paper provides a reference for the design of light source parameters, roads, walls, and warning signs in the tunnel.

Full-frame and high-contrast smart windows from halide-exchanged perovskites

Window glazing plays an essential role to modulate indoor light and heat transmission, which is a prospect to save the energy cost in buildings. The latest photovoltachromic technology has been regarded as one of the most ideal solutions, however, to achieve full-frame size (100% active area) and high-contrast ratio (>30% variable in visible wavelength) for smart window applicability is still a challenge. Here we report a photovoltachromic device combining full-transparent perovskite photovoltaic and ion-gel based electrochromic components in a vertical tandem architecture without any intermediated electrode. Most importantly, by accurately adjusting the halide-exchanging period, this photovoltachromic module can realize a high pristine transmittance up to 76%. Moreover, it possesses excellent colour-rendering index to 96, wide contrast ratio (>30%) on average visible transmittance (400-780 nm), and a self-adaptable transmittance adjustment and control indoor brightness and temperature automatically depending on different solar irradiances.

Ultrastable and high colour rendering index WLEDs based on CsPbBrI2 nanocrystals prepared by a two-step facile encapsulation method

The graphical abstract clearly and succinctly shows the synthesis method and application prospect of this study.

The elevated colour rendering of white-LEDs by microwave-synthesized red-emitting (Li, Mg)3RbGe8O18:Mn4+ nanophosphors

The bright red emitting (Li, Mg)3RbGe8O18:Mn4+ nanophosphors significantly enhanced the colour rendering of a white-LED based on blue-LED chip and YAG:Ce3+ phosphor.

Solid-state near infrared emitting platinum(ii) complexes as either an ultrathin or singly doped phosphorescence emitting layer in hybrid white OLEDs exhibiting high efficiency and colour rendering index

Two platinum complexes PBSNND and AtFNND have been used to achieve high efficiency (EQEmax of 12.9% and 13.7%) hybrid white OLEDs with an ultrathin and singly doped phosphorescence emitting layer, respectively.

Comparative Analysis Of The Characteristics Of Led Filament Lamps For Household Lighting

This paper examines the characteristics of LED filament lamps from various manufacturers: LLC “ Lisma “(Russia), an American company with production in China “ GENERAL LIGHTING CO.LTD”, a joint Chinese-Russian company “ Uniel “and Taiwan company” Smartbuy “ in the A60 bulb – the time of stabilization of characteristics, luminous flux, colour temperature, colour rendering index, flicker index, radiation spectrum during 6000 hours of burning. The research was carried out on the Gooch&Housego measuring system. The results of experimental studies that showed that the clear leader in the test results is the lamp SDF‑8 (LISMA), according to GOST of all tested samples of led filament lamps, it can be recommended for lighting in lighting devices for household lighting.