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Perovskite quantum dots with magenta LEDs can deliver 85% of the Rec2020 colour gamut

There is absolutely no doubt that Perovskite quantum dots helps to improve the image quality of LCD displays. When integrated into an LCD display in the form of a film, green perovskite quantum dots provide narrow band emission. For example, QDot™ LCD SharpGreen Perovskite film has emission centered at 527 nm with PLQY 98% and ultra narrow FWHM 17 nm (Fig.1). Such narrow band emission allows displays to both produce purer green colours and to extend the colour gamut beyond current available boundaries.

Figure 1. Photoluminescence (PL) and PLQY of QDot™ LCD SharpGreen Perovskite QDs film

However, the improvement depends to a great extent on the backlight architecture of the display. To run the display with green perovskite QDs film, the system requires blue and red narrow band sources of light. These two light sources can be in the form of either separated LED chips or the combined LED package, the so-called magenta LED. The display will perform differently depending on the type of architecture.

In our previous article we discussed the performance of the Perovskite LCD display prototype with separate blue and red LEDs backlight, in which Rec2020 coverage made up about 80%.

In this article we are going to discuss the performance of the QDot™ LCD SharpGreen Perovskite display with edge lit magenta LEDs (Fig 2).

Figure 2. LCD display prototype configuration and light spectrum

The Magenta LED is a special LED package consisting of a blue LED chip with red emitting, narrow band phosphor material. These combined LEDs simultaneously emit pure blue and red light. The main advantage of this is that only a single driving board is required to switch on the Magenta LEDs. This means that it is cost effective to mass produce the screens. With this backlight architecture, the display can yield an outstanding 86% Rec2020 ratio and 84% coverage with 1000 nits brightness (Table 1).

Table 1. Colour gamut and brightness of QDot™ Displays with Magenta LEDs

Although there are still some losses in the colour gamut (Fig 3-a), these can be mitigated by optimising the blue and red light sources and LCD colour filters. With such optimisation the colour gamut can potentially reach 96% of Rec 2020 colour gamut coverage (Fig 3-b). Brightness can also be increased by using magenta LED, as this helps increase the flux supply of the light.

Figure 3. CIE Chromaticity diagrams of QDot™ Display with (a) Magenta LEDs from the Table 1 and (b) theoretically optimised blue and red light sources and colour filters

Perovskite Technology is tapping its way into the display industry. QDot™ Perovskite technology developed by Quantum Solutions is highly efficient and reliable. It will allow display companies to manufacture displays with an ultrawide colour gamut. QDot™ Perovskite film integrated into LCD displays can reproduce more than 85% of the Rec2020 colour gamut. The film also remains stable in harsh conditions, such as temperatures 85 ◦C, relative humidity 90%, and high flux 100 mW/cm2. This ensures that the displays have a long lifespan.

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