OLED lighting luminous efficiency or up to 200lm/W?

After the luminous efficiency of 100lm/W, achieve about 130lm/W become the next target of manufacturers. Japan's new energy industry technology development agency (NEDO) pointed out that this is because it will achieve an ordinary fluorescent lamp about 2 times the luminous efficiency, while its lighting efficiency and LED lighting quite. However, 130lm/W is not the end. The luminous efficiency of organic EL lighting will be further improved, compared with the lamp efficiency, it is expected that the organic EL lighting will be the highest luminous efficiency technology in all lighting technologies. Technical personnel, American Eastman Kodak, Nanjing is now the first organic photoelectric company (First O-Lite) founder and chief technology officer Tian Yuansheng pointed out: "the theoretical limit of white organic light emitting efficiency of EL is 248lm/W, similar to white LED light source 260lm/W. "That is, in terms of lighting efficiency, organic EL lighting may be the highest. The actual luminous efficiency is also close to 200lm/W.

IHS Electronics&Media predicts that 2019 200lm/W organic EL lighting panel will be available. The U.S. Department of energy (DOE) also 190lm/W as the ultimate goal of organic EL lighting technology development. Organic EL manufacturers of American Universal Display Technology (UDC), although no mention of the specific implementation time, but said, as an organic EL lighting luminous efficiency, 180lm/W is a more realistic goal". Improve the efficiency of a series of breakthrough goals set very high, but the supply of organic EL lighting panel luminous efficiency has not yet reached. Even from a global perspective, the highest value is only LG chemical company 60lm/W. Japan's domestic products, Konica Minolta holding company's panel "Symfos" 45lm/W for the highest value, other products are mostly only about 30lm/W. There is a huge gap between the product and the target value of the future, because recently made a breakthrough, can improve the efficiency of luminous efficiency (Figure 5). In particular, the following 3 points have made great progress: (1) to improve the light extraction efficiency from the light extraction layer; (2) to improve the light extraction efficiency by suppressing the surface plasmon resonance; (3) to improve the efficiency of blue light-emitting materials.

* surface plasmon resonance (SPR) = the combination of light with the surface of the metal and the resonance in a longitudinal mode similar to the acoustic wave. (1) and (2) the light extraction efficiency, refers to the photon inside the organic EL element, can be extracted from the external photon proportion of the component. Do not work hard at this point, only about 20% of the light can be extracted to the outside. The remaining 80% is lost in the form of heat. Therefore, the improvement of light extraction efficiency is an important issue to improve the luminous efficiency of organic EL lighting.

On the improvement of the efficiency of light extraction, the professor of Jinze University of technology, three, released the important technology in 2009. The main content of this paper is that if the light extraction layer composed of glass layer and micro lens array with refractive index of up to 2 can be set on the surface of the element, it can obtain good effect. But the high refractive index glass is a big problem. In 2012, Panasonic Corp focused on the price is far lower than the high refractive index glass poly (naphthalene) two ethylene glycol ester (PEN) resin refractive index of up to 1.7 ~ 1.8. And on the SID 2012 release, the PEN film on the surface of the micro lens array and glass substrate between the air can greatly improve the efficiency of light extraction (Figure 6).

Using this technology, the light extraction efficiency is improved to about 2 times of the original 42%. The luminous efficiency of the organic EL lighting panel with luminous area of 25cm2 is 87lm/W, and the organic EL element of the 1cm2 reaches 101lm/W, which is the white light and the thin element, and the whole world exceeds 100lm/W (Figure 1 (b)) for the first time in note 3. Panasonic core technology development center technical director, Osaka University distinguished professor Da Takuya pointed out: the focus is on the high refractive index PEN and refractive index of air between the 1 great refractive index difference. "Note 3) in the 2012 SID Matsushita also announced that by setting the same with LED hemispherical light extraction layer, light emitting area of the organic EL element of the 4mm2 light extraction efficiency reached more than 62%, high luminous efficiency up to 142lm/W implementation. Asahi Glass Company (AGC) has been in the SID 2009 and SID 2012 announced by the independent method developed a relatively low price but with high refractive index and light scattering function of the glass, improves the light extraction efficiency. In 2009, the technique of adding bubbles to light scattering in glass. The 2012 release of the technology is to use a diameter of about 2 m ceramic particles to replace the difficult to control the diameter of the bubble added to the glass, thereby greatly reducing the scattering effect on the wavelength dependence of note 4). Note 4) Asahi said that in the light scattering by a particle size ranging from hundreds of nm, can be fully scattering blue light "Rayleigh scattering dominates, and the particle size is about 2 m, the wavelength dependence of the smaller" Mie "will be enhanced. About the price of glass, the Asahi said "is still in the stage of research and development, public inconvenience, but may take a strategic price setting for business. European glass manufacturers believe that "Europe has several organic EL element manufacturers have intention to adopt the estimate is Asahi production, with light scattering effect of glass".