Sony Develops An Ultra-Thin Rollable OTFT-Driven OLED Display

Sony has developed a super-flexible 80 μm-thick 4.1-inch 121 ppi OTFT-driven full color OLED display (16 million colors) which can be wrapped around a thin cylinder.

Sony's rollable OLED display, due to show at the Society for Information Display 2010 International Symposium. Photo: Sony Insider

When we, here at TheBlogIsMine.com, saw yesterday’s Sony Nextep wrist-based computer concept, we couldn’t help but thinking how futuristic it looked. Then, just a day later, here comes Sony again with this intriguing rollable OLED display.

According to Sony Insider, Sony Corp. has developed a highly flexible OTFT-Driven OLED display that can be rolled around a pencil and continue to operate.

The 4.1-inch diagonal isplay is 80-microns thick and offers 432 by 240 by RGB pixels resolution at 121 pixels per inch. It’s an organic LED full color display driven by an organic thin-film transistor matrix (Don’t forget to check the video below after the jump.)

The key to the display is the use of a peri-Xanthenoxanthene (PXX) derivative with eight times the current modulation of conventional OTFTs. This was achieved due to the development of integration technologies of OTFTs and OLEDs on an ultra-thin 20-micron thick flexible substrate together with soft organic insulators for all the insulators in the integration circuit.

The panel is capable of reproducing moving images while being repeatedly rolled-up and stretched around a cylinder with a radius of 4-mm. Sony is set to unveil the display on May 27 at the Society for Information Display 2010 International Symposium in Seattle.

Sony has so far developed a prototype and said it would proceed with the development of a production process based on printing of organic materials dissolved in solvents. Sony said the displays are expected to yield thin, light-weight mobile devices with enhanced form-factor.

Sony’s peri-Xanthenoxanthene (PXX) derivative is stable under exposure to oxygen, moisture, light and heat and improves the current modulation by a factor of eight over conventional OTFTs based on pentacene. The roll-up capability is partly possible because the rigid driver IC chips are no longer required for the display.

The display has withstood more than 1000 cycles of repeatedly rolling-up and stretching the display without degradation in the display’s ability to reproduce moving images, Sony said.

Sony's rollable OLED display, due to show at the Society for Information Display 2010 International Symposium. Photo: Sony Insider

Technology Features:

An OTFT (Organic Thin-Film Transistor) is a thin-film transistor with organic (carbon-based compound) semiconductor. The OTFT can be directly made on a flexible substrate at low temperature below typically 180°C.

It has high mechanical flexibility and therefore it is expected to realize thin, light-weight, mechanical-shock resistant and form-factor enhanced electronic devices, such as flexible display, e-paper and RF-ID tag.Because organic materials can be easily dissolved in common solvents, development of electronic circuits in a large area with solution/printed process has been attractive much attention.

Sony's peri-Xanthenoxanthene (PXX) derivative is stable under exposure to oxygen, moisture, light and heat. Image: Sony

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.

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. Image: Sony

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.

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.

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 4 mm. 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. [Sony via Sony Insider]

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