FINETECH JAPAN 2024/15th FILMTECH JAPAN/13th PLASTIC JAPAN/11th Metal Japan/4th Sustainable Material Japan
Light outcoupling efficiency in display and lighting device is enhanced by use of new materials

October 29 - 31, FINETECH JAPAN 2024/15th FILMTECH JAPAN/13th PLASTIC JAPAN/11th Metal Japan/4th Sustainable Material Japan were held in Makuhari Messe. Main topics about material in these exhibitions are picked up.

Light reflection is greatly decreased by coating elastomeric resin only

First of all, Dexerials appealed an elastomeric resin (SVR), which is possible to increase light outcoupling efficiency of OLED and LED-backlight module.

Pic.1 Samples with SVR film for instrument panel (right::SVR only,left:SVR+AR)

It's acrylic resin due to adjustment refraction index. For example, if it's coated on OLED and LCD module instead of spacer ball or column by various coating methods, reflection index is changed to 1.45 - 1.53. As a result, light outcoupling efficiency is improved because of reduction of difference of reflection index against top front plate (glass or plastic film), and also, light reflection is reduced from 12 % to 4 %. The company is mass-producing rigid models at the present moment, and will be mass-produce foldable model in near future, too.

Picture 1 shows instrument panel using SVR. Left is a sample using SVR only, right is a sample using SVR and AR film. In the left, light reflection was not almost observed.

Light outcoupling efficiency of Micro-LED is improved by combination of high and low refractive index materials

On the other hand, TAIYO HOLDINGS proposed to use high refractive index maternal and low refractive index material for microlens array (MLA), in order to enhance light outcoupling efficiency of Micro-LED. The former's refractive index is 1.7. It's patterned on RGB sub-pixels at half-sphere shape by coating, exposure, develop, and baking processes. The latter's refractive index is 1.49. It's coated patterning-free. The both can be easily coated or laminated by existing methods. By the way, enhanced effect of light outcoupling efficiency is not sure at the present moment.

Reflection loss is minimized by use of index matched ITO

Fig.1 Introduced sample of index matched ITO in LCOS

Nippon Electric Glass demonstrated index matched transparent ITO film (IMITO). It's composed of conventional ITO film and originally inorganic film. Its index is decreased from 2.2 to 1.8. Reflection loss is minimized because of reduced difference of index against front glass. Furthermore, light transmittance in the near infrared region is greatly high same as almost 100 %.

As figure 1, it's effective for LCOS(Liquid Crystal on Silicon) in the booth, particularly, best suitable for head-up display.

JFE proposed original hole transport material for organic series solar cell

As regards organic series solar cell, JFE group (JFE Steel and JFE Chemical) proposed metallic oxide film was deposited as electron transport material by electrolytic plating method following last year, and also, original hole transport material for perovskite solar cell in this time.

Fig.2 Molecular design of hole transport layer material

Figure 2 shows molecular structure of convectional Spiro-OMeTAD and new material. Its aim is to enhance hole transport efficiency from perovskite layer by devise of functional group. And also, film flatness is expected to be smoothed. By the way, manufacturing cost is inexpensive than existing competitor in principal, because of fluorene material, which is generated as residual product in iron manufacturing process.

In the booth, small perovskite solar cell and practical organic film solar cell using electron transport material and hole transport material were exhibited. In the former, substrate with this film will be supplied or manufacturing technology will be licensed, on the other hand, in the latter, material itself will be supplied to device makers.

Pic.2 Encapsulated organic film solar cell by solid encapsulation

Reiko exhibited solid encapsulation materials for organic film solar cell

By contrast, Reiko exhibited solidly encapsulated organic film solar cell by high transparent low resistance film and high-barrier film. In the former, conventional ITO film is deposited on PET film with coating layer. Its sheet resistance and light transmittance are 14.9 Ω/□ and 87.2 % respectively. Furthermore, workability of laser cutting is excellent.

The company will supply stack film of high-barrier film/sealing material/high transparent low resistance film. Flexible device can be relatively manufactured because of above layer structure in spite of use of conventional ITO film. By the way, water vapor permeability (WVTR) is approximate 5×10^-4g/m²/day.

New functions are generated by fine concavity and convexity structure on substrate

Pic.3 Samples of fine concavity and convexity structure

Nippon Electric Glass demonstrated fine concavity and convexity structure technology. Fine array structure are directly fabricated on surface of substrate, such as, glass and ceramics by not nanoimprinting method, photolithography methods but originally mechanical method. Its applications are widely, such as, control of write feeling in touch panel, enhanced adhesion, improved wettability, reduction of reflection, and so on. As concerns wettability, contact angle of water is increased from 35°to 135°by this array structure. In the booth, many samples with various write feelings were exhibited. The company has shown write feelings could be configured at will.