54.1: Invited Paper: A Novel Approach to Make Flexible Active Matrix Displays

Abstract

A flexible thin film transistor (TFT) backplane was successfully developed with Polyimide (PI) substrate and a novel de-bonding technology. The PI is colorless and transparent which can sustain a process temperature of 200 o C. With this progress, flexible organic light emitting diode (OLED) and electrophoretic display (EPD) can readily be integrated with flexible TFT backplane to fabricate flexible AMOLED and flexible AMEPD. IntroductionSince AMOLED possesses several attractive properties such as self-emissive, high video rate, wide color gamut, low power consumption, and simplicity in structure [1], it is considered most promising for flexible displays. To accomplish flexible AMOLEDs, it is required to integrate compatible processes of flexible substrate, TFT backplane, and OLED. However, development of flexible substrate and compatible de-bonding technology are presently among the most challenging tasks for the fabrication of flexible AM display. The requirements of flexible substrate include surface performance, thermal stability, reliability, and proper adhesion properties for transfer from rigid objects. Several types of substrates, including ultra-thin glass, plastic, and stainless steel have been considered as possible substrates [1-4]. Currently, the flexible substrates are mainly prepared first by either laminating or coating them on glass carriers, followed by fabricating TFT devices on the said substrates. The structure of laminating type substrate consists of metal or plastic foils (examples: PC, PET, PEN, PES, PI, etc.), adhesive glues and glass. The coating type substrate includes polymeric solutions (e.g. PI), de-bonding layers and glass. Since the drawbacks with laminating type substrate technology such as thermal expansion of adhesive glues have been widely published, we therefore decide to select the coating type substrate for our technology. However, de-bonding of flexible TFT devices is not without issues either with coating type substrate. Recently, two de-bonding methods, including EPLaR process [5-6] by Phillips and de-bonding layer (DBL) by ITRI, were developed to for the coating type substrate technology. Such advances of flexible substrate technologies will promote further growth of flexible AM displays and related applications. MethodsThe PI material is custom synthesized in ITRI, and a subject of another invited paper in this conference. The PI solution was coated after depositing DBL on glass as a flexible substrate later for AM display. The area covered by PI is intentionally made larger than that of DBL's. The glass substrate was thereafter subjected to the TFT backplane fabrication process on ITRI's Gen. 2 (370×470 mm 2 ) glass line. Top gate a-Si:H and μc-Si TFTs were fabricated by 6-mask processes and the process temperature was at 200 o C. The OLEDs were deposited and encapsulated by conventional OLED fabrication procedures. ResultsA novel flexible substrate technology compatible with the existing TFT infrastructures and processes was developed by ITRI. This technology, schema...

High‐performance organic‐inorganic hybrid plastic substrate for flexible displays and electronics

“…10, the MCL-PI coated on glass was used to make a µc-Si TFT backplane at ITRI/DTC and was peeled off from the glass substrate. 10 Moreover, other applications by using this approach are demonstrated in Fig. 11.…”

78-1:Invited Paper: Foldable AMOLED Integrated with On-cell Touch and Edge Sealing Technologies

“…For the next generation products, we believed that the "ability to fold" feature will further differentiate flexible displays from the conventional glass-based panels. Our team's goal is to develop a foldable display on flexible universal plane (FlexUP) [4][5][6][7], which is flexible, low stress, and has mechanical, thermal stability. Also, OLEDs are vulnerable to the moisture and oxygen, which penetrate the periphery of the OLED display and through the defects in thin film encapsulation (TFE) layers.…”

Direct imaging exposure equipment with high overlay accuracy for flexible substrate in roll‐to‐roll method

“…At first, electronic devices are fabricated on a polymer film, which is formed on a support substrate. Next, the polymer film, on which electronic devices are fabricated, is released from the support substrate . This method is complicated and poor in yield, and hence, devices fabricated by this method tend to be expensive.…”

“…Next, the polymer film, on which electronic devices are fabricated, is released from the support substrate. [4][5][6] This method is complicated and poor in yield, and hence, devices fabricated by this method tend to be expensive.…”