CEATEC 2024
Nippon Shokubai mass-produces flexible OLEDs at beginning of 2025

October 15 - 18, CEATEC 2024 were held in Makuhari Messe. Main topics are closed up in this here.

First of all, Nippon Shokubai exhibited various flexible OLEDs "iOLED", and also, announced to mass-produce iOLED in the near future.

Pic 2. Origami like iOLEDs

Pic 1. Flexible OLEDs

The company developed a new electron injection material instead of conventional alkali metal in the past. Durability against H2O was greatly enhanced by use of organic strong base as electron injection material. Required water vapor permeability is 10^-3〜^-4g/m²/day. In short, it's lower at 2 - 3 digits compared to reference with alkali metal. For this reason, it's satisfy required water vapor permeability by PEN film with barrier film and encapsulated PEN film with barrier film. Of course, desiccant is not necessary.

In the booth, basic shape and various flexible shapes were exhibited. Particularly, as picture 2, it's possible to manufacture origami shape device, which is difficult to manufacture in other devices.

The company is supplying samples in the present moment, and will to start massproduction at beginning of 2025 by sheet-to-sheet method (not roll to roll method).

Pic 3. A0 size E-PAPER signage

Sharp disclosed ultra-large e-poster

As concerns E-paper display, Sharp exhibited an ultra-large (A0 size) e-poster. Microcapsule type electrophoretic display module were mounted on the glass with TFT. Of course, consumed power is not wasted except for rewriting time of image.

As picture 3, solar panel and lamp were set up at upper side, and IoT connect module was set up at lower side. It's possible to rewrite display image at night because of power generation and power storage at daylight, and also, to rewrite at real-time by remote operation.

Curtain LED was developed by use of PI film with low-thermal expansion

NAGASE exhibited a 100-inch curtain LED "PANELSEMI". It's composed of tiling mini-LED units on Xenomax Japan's original polyimide (PI) film (Xenomax) with low-thermal expansion. It can be housed like a curtain by tiling structure. Of course, it's easy to manufacture rotary type LED because of thin substrate.

Pic 4. Curtain LED

By the way, feature of Xenomax is the following：�@Heat resistance is greatly high same as 500℃, �ALinear coefficient of expansion is low same as 0 - 3 ppm/℃, which is almost same value of glass, �BSurface flatness is mere Ra = 0.5nm.

Panasonic appeals perovskite solar cell with glass substrates

With respect to perovskite solar cell, Panasonic demonstrated prototype with glass substrates. Incident-photon-to-current efficiency (IPCE) is 18.1 %, which is world's best in practical size (30×30cm).

Pic 5. Comparison of light transmittance (light:20 %, left:40%)

As picture 5, optical transmittance can be controlled at will by laser cutting technology. However, it will be sample-supplied at 2026, and mass-produced at 2029.

E-Paper is driven by solution-processed organic-TFT

As regards TFT, Yamagata University (Mizukami-Lab) reported to drive 2.1-inch E-Paper displays (146×240 dot) by solution-processed organic-TFT. It's a bottom gate-bottom contact structure using DTBDT-C6 organic semiconductor. All organic materials inclusive of DTBDT-C6 were deposited by solution process.

Pic 6. E-Paper by solution processed organic-TFT

Its carrier mobility is 2.74 cm²/V･s and Vth is 0.4V respectively. Not only E-Paper display, but also, low resolution OLED can be driven by this organic-TFT.

Gas barrier film is formed by densification process

Another research group of Yamagata University (Suzuri-Lab) proposed original gas barrier process of solution process and densification process with VUV (vacuum ultraviolet) light irradiation.

In this densification process, PDMS (polydimethylsiloxane) is coated, and then, is irradiated N2 and room temperature environment by VUV (172 nm) light, as a result, is changed to SiOx film as planarization layer. On the other hand, PHPS (perhydro-polysirazane) liquid is coated, and then, is irradiated by VUV light, as a result, is changed to SiNx film.

Fig 1. Water vapor permeability

Pic 7. TEM image of gas barrier stack structure

This SiOx/SiNx layers is base unit. It's stacked by required gas barrier characteristics. As picture 7, water vapor permeability is 2.2×10^-4g/m²/day in 1 unit, and 5×10^-5g/m²/day in 3 units. In short, it's used for perovskite solar cell, required gas barrier characteristics is ensured in 1 unit.

By the way, this stack structure is useful for not only device substrate, but also, encapsulation. In the latter, it's necessary to coat PDMS without solvent firstly, in order to prevent damage against formed organic layers.

Transparent conductive film with both advantages of ITO and polymer is developed

As concerns material, Murata Manufacturing proposed a newly transparent conductive film as candidate of ITO film.

Fig 8. Transparent heater with new transparent conductive film

Dispersion liquid contain of original ceramics powder is coated on substrate by various coating methods, and then, dried at 50 - 100 ℃, as a result, transparent conductive film is obtained. In short, ceramics powder itself is adsorbed to the substrate. For this reason, it's not film shape, unlikely a ITO. Therefore, flexibility property is excellent, such as R = 0.2 mm. In a word, it has both advantages of ITO and organic polymer. In fact, optical transmittance and conductive property are 90 % and 18,000 S/cm respectively.

In the booth, a flexible heater using this film was exhibited. If this film is used, flexible and transparent device can be easily manufactured.