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D7.2.1

Organic Memory Devices Using C60 and Insulating Polymer Alokik Kanwal, Shashi Paul and Manish Chhowalla Ceramic and Materials Engineering, Rutgers University Piscataway, NJ 08854 ABSTRACT In this paper, we describe an all organic molecular memory device that combines the advantages of molecular and organic electronics. We accomplish this by combining C60 molecules with poly(4-vinylphenol) (PVP) and co-dissolving them in iso-propanol. The currentvoltage measurements show a large hysteresis in the blend devices, in contrast to pure PVP devices. The thin blend films have been thoroughly characterized using Raman spectroscopy, atomic force microscopy and scanning electron microscopy. INTRODUCTION The ease of fabrication and use of inexpensive substrates has generated tremendous interest in organic electronics [1 and references there in] while molecular electronics offers the potential of miniaturization down to a few atoms. However, unlike organic electronic devices, molecular devices are difficult to assemble making mass production impossible using existing technology. Although several types of single molecule devices have been demonstrated, molecular memories have shown promise towards technological feasibility [2]. In contrast, there have been relatively few reports of organic memory devices, although recently they have received higher profile [3-6]. A recent article by Scott [3] raises several issues related to emerging memory devices technology. He argues that although there is a clear demand for the next generation of non-volatile solid state memories, the newcomer memory devices must exceed the existing speed and cost constraints of today’s entrenched technologies. In addition, the new technology must also meet other critical performance criteria such as long term data retention (at least 10 years and up to 100 years for archiving), low power consumption (a few milliwatts or less for flash type of memory which is equivalent to 1nJ to write and 1pJ to read per bit) and large number of rewrite cycles (Flash memories are rated for 106 cycles while DRAM are rated for > 1015 cycles). We propose the development of an all organic memory device that combines the advantages of molecular and organic electronics. Specifically, we have demonstrated nonvolatile memory devices using C60 fullerene molecules dispersed in an semi-insulating (poly(4vinylphenol) [PVP]) polymer. Our work shows that the devices exhibit high and low conductance states, rapid switching, low power consumption, long term cycling stability and data retention which renders them suitable for membership in the class of non-volatile, high speed and inexpensive memory devices. The devices can be fabricated at room temperature using spin coating and therefore are easily scalable for mass production. EXPERIMENTAL DETAILS PVP polymer is electrically semi-insulating and easily dissolves in isopropyl alcohol at ratio of 25mg to 1ml. The C60 fullerene molecule is a closed cage molecule with a precise

D7.2.2

diameter (0.72 nm) consisting of 60 carbon atoms