Bistable Electrical Switching and Rewritable Memory Effect in a Thin Film Acrylate Copolymer Containing Carbazole-Oxadia
- PDF / 396,972 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 40 Downloads / 188 Views
1114-G05-02
Bistable Electrical Switching and Rewritable Memory Effect in a Thin Film Acrylate Copolymer Containing Carbazole-Oxadiazole Donor–Acceptor Pendant Groups E.Y.H. Teo1, Q.D. Ling2, S.L. Lim3, K.G. Neoh2, E.T. Kang2, D.S.H. Chan1, C.X. Zhu1 1
Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge, 119260, SINGAPORE 2 Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210046, CHINA 3
Department of Chemical and Biomolecular Engineering, National University of Singapore, 10 Kent Ridge, 119260, SINGAPORE
ABSTRACT The molecular conformation-dependent write-once read-many-times (WORM) memory based on an acrylate polymer containing pendant carbazole (donor) groups is transformed into a flash (rewritable) memory when acrylate units containing pendant oxadiazole (acceptor) groups are incorporated to form a copolymer. The as-fabricated device based on the acrylate copolymer containing carbazole-oxadiazole donor-acceptor pendant groups is in its low conductivity state and can be written to a high conductivity state at a threshold voltage of -1.8 V. The high conductivity state can be switched (erased) to the low conductivity state with a positive bias of 3.6 V. The device exhibits a high ON/OFF current ratio of 103 at a read voltage of -1 V. This rewritable polymer memory can be programmed and erased repeatedly with good accuracy. The copolymer is potentially useful for application in flash memory devices.
INTRODUCTION Electroactive organic materials have been widely explored as light emitting diodes [1], transistors [2], solar cells [3] and recently memory devices [4]. Compared to their inorganic counterparts, the advantage of organic materials lies in the fact that their electronic properties can be easily tuned, by structural design, synthesis and modification, to exhibit a series of memory functions. These memory functions have ranged from that of a write-once read-manytimes (WORM) memory [5] to that of a dynamic random access memory (DRAM) [6], or that of a flash (rewritable) memory [7]. The use of solution based processing techniques, such as spin coating, ink-jet printing and stamping [8], allows for the low cost and ease in fabrication. Many studies on the organic memory devices are based on solution-processable polymeric materials [9,10]. The basic requirement for a polymer to exhibit memory behavior is to possess two accessible states, corresponding to, for example, the high conductivity and low-conductivity response to the same applied voltage. To function as viable memory devices, the polymer memories must possess a high ON/OFF current ratio between the conducting and non-
conducting states to minimize any error during the read cycle, as well as exhibit a long retention time for their ON and OFF states. 1,3,4-Oxadiazole and its derivatives [11] are electron acceptors and are commonly used as electron-transporting units in optoelectronic devices, whereas carbazole and its derivatives [12] are electro
Data Loading...
