Paul S. Drzaic

Surface-Modified Nanotube Anodes for High Performance Organic Light-Emitting Diode

In this work, we reported high performance OLED devices with transparent and conductive carbon nanotube anodes after modification. The modifications include IMRE proprietary PEDOT:PSS composite top coating (PS(C)), concentrated HNO(3) acid soaking, and polymer encapsulation. For PS(C)-modified nanotube thin film anode, we achieved maximum luminescence of approximately 9000 cd/m(2), close to ITO-based OLED device performance, and high efficiency of approximately 10 cd/A, similar with ITO-based OLED device. The performance is approximately 30 to 450 times better than that achieved for OLED devices using CNT anodes by others. In addition, we also investigate the mechanical property, work function, sheet resistance, and surface morphology of modified carbon nanotube thin-film anodes.

37.4: Late‐News Paper: Integration of Carbon Nanotube Transparent Electrodes into Display Applications

Carbon nanotube (CNT) thin films for transparent, conducting electrodes are introduced for display device applications. We have vertically integrated the CNT thin films from synthesis to integration on devices. Here we report the brief characteristics of the CNT network thin film and process feasibility of the CNT films for TFT pixel and common electrodes in TFT-LCDs.

Scalable Carbon Nanotube Thin Films: Fabrication, Properties and Device Applications

Carbon nanotubes (CNT) have been under investigation for many years as a material suitable for applications in electronic devices. This paper will focus on the development and production of high quality, high performance, and scalable transparent and conductive CNT thin films using solution based roll to roll coating methods. We demonstrate both additive and subtractive methods for patterning conductive nanotube films. Various types of devices incorporating CNT thin films are demonstrated, including EPD e-paper, touch screen, OLED, flexible OPV, and TFT-LCD. Issues involving the integration of CNT electrodes into various devices are discussed, in particular conformal step coverage. Optical and mechanical properties, environmental stability and large scale uniformity together make Unidym’s CNT thin films a viable alternative to transparent conductive oxides in applications requiring transparent, conductive electrodes. INTRODUCTION Thin films of carbon nanotubes (CNT) are a promising candidate in the development of alternatives to indium-tin-oxide thin films in applications requiring transparent, conductive films, and have been investigated by a number of groups. Films with high conductivities up to 6000 S/cm have been reported, and CNT integration into various devices such as organic solar cells, OLEDs, and LCD prototypes have been demonstrated. 1-6 However, most of these systems have suffered from one or more limitations. These limitations have included the high cost of CNT materials, film fabrication processes that are not scalable to large volumes, inferior conductivity, and poor lifetimes. Here we report the fabrication of high performance, scalable CNT films useful in applications for transparent conductors, and describe some applications of these materials demonstrating their usefulness in devices. RESULTS CNT material is synthesized by Unidym by thermal CVD using a proprietary catalyst and reactor system, and formulated into an aqueous ink with the proper rheology for slot-die roll-toroll coating. The concentration of the CNT inks range from 0.2 mg/ml to 1.5 mg/ml, depending on the formulation (Figure 1(a)). CNT thin films were coated by using a conventional roll-to-roll slot-die coater with a custom die head. As show in Figure 1(b), the speed of coating can go up to 150 feet per minute. The ink formulation, ink-substrate interaction, drying and encapsulation are critical to obtain uniform and stable CNT thin films. Unidym has demonstrated 2000 ft long CNT coating which meets the specifications of most resistive and capacitive touch panel applications. Figure 1 (c) shows a 30 inch wide and 2000 ft long roll of CNT coating on PET substrate.

P-112: Inkjet Printed Organic Thin-Film Transistors with CNT S/D Electrodes for Flexible Displays

In this work, we fabricated inkjet printed OTFT with CNT source-drain electrode for plastic displays. 6,13-bis(pentylphenylethynyl)pentacene was used for printable organic semiconductor. The OTFT with CNT electrode exhibited the field-effect mobility of 0.15 cm2/Vs, threshold voltage of −3.4 V with on-off current ratio of ∼107. The performance is suitable for driving e-paper display on plastic. Especially normalized contact resistance was 10 times lower than that of bottom-contact pentacene TFT using Au S/D electrode.

P-87: Carbon Nanotube Film on Plastic as the Touch Electrode in a Resistive Touch Screen

Carbon nanotube (CNT) films on plastic are incorporated as the touch electrode in a four-wire resistive touch panel. Touch actuation testing shows superior mechanical performance to ITO touch electrodes. Refractive index matching leads to CNT panels with lower reflection. Direct printing on polycarbonate is demonstrated. Patterning options are discussed.