Sony Develops an OLED Display That Can Wrap Around a Pencil
Sony Corporation announced today that it developed a super-flexible 80-micrometer-thick 4.1-in 121 ppi OTFT-driven full-color OLED display which can be wrapped around a thin cylinder.
To create the display, Sony developed OTFTs with an original organic semiconductor material (a PXX derivative) with eight times the current modulation of conventional OTFTs. This was achived due to the development of integration technologies of OTFTs and OLEDs on an ultra-thin 20µm-thick flexible substrate (a flexible on-panel gate-driver circuit with OTFTs which is able to get rid of convetinal rigid driver IC chips interfering roll-up of a display) and soft organic insulators for all the insulators in the integration cuircuit. By combining these technologies, Sony successfully demonstrated its first OLED panel which is capable of reproducing moving images while being repeatly rolled-up -- around a cylinder with a radius of 4mm -- and stretched.
Technology features:
- High performance OTFT with originally developed high-mobility and highly-stable organic semiconductor materials, PXX derivatives.
Sony has developed organic semiconductor material, peri-Xanthenoxanthene (PXX) derivative, which is stable under exposure to oxygen, moisture, light and heat and improved current modulation of eight times that of conventional OTFT with organic semiconductor of pentacene. Improvement of this OTFT achieved the world's highest-resolution OTFT-driven OLED display with resolution of 121 ppi and 432 x 240 x RGB (FWQVGA) pixels.
- Integration of a flexible gate-driver circuit with OTFTs.
This is the world's first demonstration of an OLED display with an integrated gate-driver circuit with OTFTs. The improvement of the OTFT described above enables integration of a flexible gate-driver circuit with OTFTs on a display panel. The roll-up capability is possible because the rigid driver IC chips has been removed from the display.
- Enhancement of flexibility with all organic insulators in the OTFT and OLED integration circuit.
In order to enhance flexibility of the display, Sony has developed organic insulators for all the insulators in the OTFT and OLED integration circuit. These organic insulators can be formed with the solution process in the atmosphere which is requires fewer steps, and consumes materials and energy more efficiently - thus has a smaller environmental footprint -- compared to the conventional high temperature vacuum semiconductor process which use inorganic/silicon materials.
- Achieved display capable of reproducing moving images while rolled-up around cylinder with 4mm radius.
The OTFT-driven OLED display with the aforementioned technologies (1-3) can reproduce moving images while rolled-up around a cylinder with a radius of 4mm. Even after 1000 cycles of repeatedly rolling-up and stretching the display, there was no clear degradation in the display's ability to reproduce moving images.
OTFT specifications:
- Organic semiconductor: peri-Xanthenoxanthene(PXX) derivative
- Hole mobility: 0.4 cm2/Vs
- Current on/off ratio: 106
- Channel length: 5µm
- Threshold voltage: -5V
Rollable OTFT-driven OLED display specifications:
- Panel size: 4.1 inch wide
- Pixel number: 432 x 240 x RGB pixels
- Pixel size: 210µm x 210µm
- Resolution: 121 ppi
- Colors: 16,777,216
- Peak luminance: >100 cd/m2
- Contrast ratio: >1000:1
- Minimum bending radius: 4mm
- Driving scheme: 2T-1C voltage programming with OTFTs
- Panel thickness: 80µm
Source: Sony Corporation
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