CRI - Page 2

Ason Technology was established in 2006 in Japan to develop OLED lighting technologies. In November 2013 Ason unveiled their first OLED lighting panel, and today we're bringing new details on the company's technology and business.

Ason spent almost eight years to develop a new multi-stack structure. Compared to the multi-photo-emission (MPE) structure developed by IMES, Ason's stack enables many layers (MPE allows up to 2 or 3 max). Stacking several layers allows the OLED panels to feature a high brightness without compromising the lifetime. In addition to the so-called Ason-Stack, the company also uses a unique diffuse reflector. Ason says that their technology will allow them to produce relatively affordable and efficient high-brightness OLEDs, which will also feature a longer lifetime and larger size compared to traditional OLED as well as no-angle dependency.

On March 2014, Konica Minolta announced it developed the world's most efficient OLED lighting panel - at 131 lm/W. Only two months later, the Japanese company announced it developed an even more efficient panel at 139 lm/W.

Konica's new panel has an emitting area of 15 square centimeters, a lifetime of 55,000 hours (LT50) at a brightness of 1,000 cd/m² and a CRI of 81. The color temperature is 2857K.

Universal Display report several OLED technology advances at DisplayWeek. First up, the company is showing several advances in OLED lighting. UDC is presenting a new approach to make white OLEDs. The panels are based on RGB stripes, each controlled with a separate current driver. UDC says that this approach potentially improves the OLED panel performance, manufacturing yield, brightness uniformity and color-tunability.

UDC calls this new architecture "RGB monochrome striped", and they demonstrate a 15x15 cm color-tunable white OLED that features an effifacy of 63 lm/W and a color temperature of 3000K. UDC is also showing a 100 lm/W all-phosphorescent warm white OLED with a lifetime (LT70) of 60,000 hours at 1,000 cd/m². Finally, UDC is also showing a remarkable high R9 warm white WOLED with CRI of 96.

LG Chem announced the world's largest OLED lighting panel at 320x320 mm (and it's only 1 mm thick!). The N6SD30 features 60 lm/W, 850 lumens brightness (max 1,000), a high CRI (>90) and a color temperature of 3000K.

The lifetime of the N6SD30 is 40,000 (LT70) at 3,000 cd/m². LG Chem says they managed to extend the panel's lifetime (compared to their older panels) mainly by using the company's own  Face Seal encapsulation technology. In fact, LG Chem upgraded all of their OLED panels to feature this new encapsulation and so all of their panels now feature 40,000 (LT70) lifetime hours.

Panasonic demonstrated three new OLED lighting panels at a LED trade show in Tokyo. First up is a flexible panel - this is the first time Panasonic demonstrated a flexible OLED. They did not reveal any specification - beside the fact that it is only 0.4 mm thick.

The second panel is a 10x10 cm panel that offers a luminous efficiency of 100 lm/W. Panasonic already unveiled a 114 lm/W panel back in 2013 - but it was a lot smaller (1x1 cm). According to Tech-On, the panel is not very bright and is also rather yellowish in color and they suspect that the CRI is low. Panasonic says that the emphasis has been on efficiency for this panel, and they wouldn't reveal specifications such as lifetime, CRI, color temperature, etc.

Ason Technology was established in 2006 in Japan to develop OLED lighting technologies. The company finally unveiled their first OLED lighting panel during the FPD International 2013 exhibition last month.

Ason's panel use Multi-Photo-Emission (MPE), which is a stacked emitter architecture, which is also used by Lumiotec. Usually MPE panels use about 3 layers, but Ason managed to stack 10 or more emitting layers which enables them to reach a very high brightness and CRI. Ason also developed their own diffusion reflection layer so that the emitted color does not change even when viewed from different angles.

Researchers from Taiwan's National Tsing Hua University developed a candlelight-style OLED lighting panel - with a low (1900K) color temperature. To create this device they used four organic electrophosphorescent dyes (red, yellow, green, and sky-blue) that create two emissive layers (blue and orange).

The researchers explain that high color temperature can drastically suppress the generation of melatonin (MLT), a naturally occurring hormone (normally produced at night) that is important for the regulation of the body's circadian rhythms. They say that medical experts have called for the development of new lighting sources with low color temperatures, free of blue emission. Currently no electrical lighting device exists with a color temperature below 2000K. The lowest color temperature is around 2500K for incandescent bulbs. A candle has a temperature of 1910K at its brightest spot.

In June LG Chem announced that all its OLED panels now have a CRI of over 90. CRI determines a light source ability to reproduce colors on which the light shines, and a high CRI means a "high light source quality". Today they released a nice video explaining why is it important to have a high CRI and restating the company's commitment to OLEDs:

LG Chem says taht CRI and efficiency are trade-off factors, but LG Chem managed to maintain high panel efficiency (60 lm/W), color temperatures between 3000K and 4000K and lifetime at 20,000 hours.

LG Chem announced that since April 2013, all its OLED panels have a CRI of over 90. CRI determines a light source ability to reproduce colors on which the light shines, and a high CRI means a "high light source quality".

LG Chem says that generally, CRI and efficiency are trade-off factors, but LG Chem managed to maintain high panel efficiency (60 lm/W), color temperatures between 3000K and 4000K and lifetime at 20,000 hours.

Panasonic Corporation developed a white OLED lighting panel that is the world's highest luminous efficiency - 114 lm/W for a light-emitting area of 1 cm². Panasonic also developed a larger panel (25 cm²) with 110 lm/W. The panels also feature long lifetime - over 100,000 hours (LT50) and a brightness of of 1,000 cd/m². The panel thickness was less than 2 mm.

Panasonic 114 lm/W OLED panel

To achieve this high efficiency, Panasonic focused on an all-phosphorescent design (with an optimal stacked layer design) and new light extraction technology. Panasonic used a Built-up Light Extraction Substrate (BLES) by optimizing the arrangement of the film, glass and air to suppress light confinement in the OLED. This enable them to achieve about 2.5 times improvement in the light extraction efficiency, which is about 50% in the new panels. Panasonic says that in older technology the light extraction efficiency stayed below 40%. Panasonic says they hold 30 patents in Japan and 17 overseas - all related for this new development.