- Nano Express
- Open Access
Focused Role of an Organic Small-Molecule PBD on Performance of the Bistable Resistive Switching
© Li et al. 2015
- Received: 18 October 2015
- Accepted: 10 November 2015
- Published: 16 November 2015
An undoped organic small-molecule 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) and a kind of nanocomposite blending poly(methyl methacrylate) (PMMA) into PBD are employed to implement bistable resistive switching. For the bistable resistive switching indium tin oxide (ITO)/PBD/Al, its ON/OFF current ratio can touch 6. What is more, the ON/OFF current ratio, approaching to 104, is available due to the storage layer PBD:PMMA with the chemical composition 1:1 in the bistable resistive switching ITO/PBD:PMMA/Al. The capacity, data retention of more than 1 year and endurance performance (>104 cycles) of ITO/PBD:PMMA(1:1)/Al, exhibits better stability and reliability of the samples, which underpins the technique and application of organic nonvolatile memory.
- Small molecule
- PBD:PMMA nanocomposite film
- Nonvolatile bistable resistive switching
Organic memory, a multidisciplinary and flourishing frontier of nanotechnology, has succeeded in significant breakthroughs [1–4]. As emerging information medium, devices function as the transmission and manipulation of data, based on organic semiconductor embracing small molecule and polymer. In contrast to inorganic resistive random access memory [5–8], organic resistive random access memory (ORRAM) obtains access to meet the requirements of data storage, large-scale, low-cost, flexible nonvolatile storage for commercialization and utility.
1,3,4-oxadiazole and its derivatives are the group of electron-transport luminescent materials in the domain of organic light emitting diodes (OLEDs). The organic small-molecule material, 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD), predominantly emits either blue or purple light, offsetting the deficiency of blue or purple luminescent materials . Nonvolatile memory on 1,3,4-oxadiazoles acting as an electron-acceptor mainly focuses on donor-acceptor (D-A) copolymers [10–12]. Transparent material, poly(methyl methacrylate) (PMMA), is used to manufacture various illuminant equipments, optical glass, and optical fiber. For ORRAM, inorganic materials as reported cover quantum dots [13, 14], such as CuInS2-ZnS core-shell quantum dots and thiol-capped CdS quantum dots, oxide nanoparticles (NPs) ZnO , and carbon nanomaterials like graphene, CNTs, and fullerene together with its derivatives [16–21], which can be embedded into the insulator-like matrix PMMA.
Not only single organic materials, such as poly(N-vinylcarbazole) (PVK) that is widely accepted, but nanocomposites with polymer-polymer or polymer-inorganic blending have unfolded for the research on organic memory. Progressively, ORRAM based on small molecule is attached to great importance. The spin-coated PBD and PBD:PMMA nanocomposite film, first and foremost, were characterized by means of Raman spectrum, scanning electron microscope (SEM), UV–Vis spectroscopy, cyclic voltammetry (CV), and transmission electron microscopy (TEM). The following work highlights the tunable effect of the organic material PBD and its nanocomposite blended by PMMA on electrical properties, and retention and endurance of the resistive switching were additionally detected.
2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole or PBD:PMMA blends with proportionality of the chemical composition 1:1 was dissolved into the chloroform with the concentration of 0.5 wt.%. At ambient temperature, the solution was stirred by the magnetic stirrer for more than 24 h. Impurities were then removed by the percolation of a 0.45-μm filter. The glass substrate, with the indium tin oxide (ITO, 2000 Å thick) deposited, was sequentially cleaned by the acetone, methanol, and ethanol and proceeded to be kept 40 °C in the vacuum furnace for 30 min. After spin-coating the solution uniformly to fabricate an active layer at 3000 rpm, the solvent was eliminated from the coatings through the vacuum furnace in 70 °C for 2 h. Later, the top aluminum electrode, 300 nm thick, was deposited on the PBD or PBD:PMMA hybrid film and protected by the mask layer with the mask pattern diameter 2 mm. The ITO electrode acts as the anode while the alternative can be seen as the cathode.
where the reference energy level of ferrocene (FOC) is 4.8 eV, the external standard potential of the ferrocene/ferrocenium ion couple E FOC vs. the Ag/AgCl reference electrode is 0.43 eV measured by CV. E HOMO (−5.95 eV) and E LOMO (−2.47 eV) can be figured out, whose distribution is depicted in inset of Fig. 2b. JEM-2100 transmission electron microscopy (TEM) was adopted to characterize the surface of the PBD:PMMA(1:1) nanocomposite film in Fig. 2c, d, from which the PBD in the PBD:PMMA(1:1) film presents zonal distribution. Thus, the energy band diagram of ITO/PBD:PMMA/Al can be described in Fig. 2e.
where φ is the height of the potential barrier, m* is the efficient mass of holes in the polymer semiconductor, and q and h are the quantity of electric charge and Planck constant, respectively. Depicted in the correlation between ln(I/V 2) and 1/V in Fig. 5 c, d, the write process has the negative resistance conduction because the current dramatically increases during the forward scan, consistent with the Fowler-Nordheim (FN) tunneling model.
This paper weighs the electrical properties of the undoped and doped PBD films. Although the components of this nanocomposite PBD:PMMA are relatively independent, its performance does not simply add up with the fact that the ON/OFF current ratio is subject to significant enhancement. The bistable behavior of the resistive switching by means of blending PMMA obviously heightens that of the PBD film, which has higher ON/OFF current ratio, and better retention and endurance performance, with the proportionality of the chemical component PBD:PMMA(1:1). Consequently, it provides a widespread prospect for the application of nonvolatile memories.
This work has been supported by China Postdoctoral Science Foundation (2011 M500701), the National Science Foundation of China (61204127, 21372067), and the Doctoral Fund of Ministry of Education of China (20132301110001).
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- Jagan SM, Simon MS, Umesh C, Tseung YT (2014) Overview of emerging nonvolatile memory technologies. Nanoscale Res Lett 9:526View ArticleGoogle Scholar
- Jian TL, Ai WT, Xu L, Ya PC, Miao W, Yu N, Long FL, Qi PL, Yun ZL, Yu FH, Yan BH, Feng T (2014) Negative differential resistance and carrier transport of electrically bistable devices based on poly(N-vinylcarbazole)-silver sulfide composites. Nanoscale Res Lett 9:128View ArticleGoogle Scholar
- Byungjin C, Sunghun S, Yongsung J, Tae-Wook K, Takhee L (2011) Organic resistive memory devices: performance enhancement, integration, and advanced architectures. Adv Funct Mater 21:2806View ArticleGoogle Scholar
- Yan MS, Lei L, Dian ZW, Xu DB, Gang L (2015) Bistable electrical switching and nonvolatile memory effect in carbon nanotube-poly(3,4-ethylenedioxythiphene): poly(styrenesulfonate) composite films. Phys Chem Chem Phys 17:17150View ArticleGoogle Scholar
- Guo MW, Shi BL, Zhao AY, Mei YZ, Yang L, Ding LX, Hang BL, Qi L, Xiao BY, Ming W, Xiao XX, Hong TL, Bao HY, Ming L (2015) Impact of program/erase operation on the performances of oxide-based resistive switching memory. Nanoscale Res Lett 10:39View ArticleGoogle Scholar
- Debanjan J, Sourav R, Rajeswar P, Mrinmoy D, Sheikh ZR, Rajat M, Siddheswar M (2015) Conductive-bridging random access memory: challenges and opportunity for 3D architecture. Nanoscale Res Lett 10:188View ArticleGoogle Scholar
- Dian ZW, Xiao HB: Nanostructure quick-switch memristor and method of manufacturing the same. 2013, US Pat 8 487 294 B2.Google Scholar
- Dian ZW, Xiao HB: Method of manufacturing nanostructure quick-switch memristor. 2013, US Pat 8 609 459 B2.Google Scholar
- De WZ, Zheng X, Fu JZ, Shu FS, Su LZ, Yong W, Guang CY, Yan FZ, Hong HX (2007) The effect of electric field strength on electroplex emission at theinterface of NPB/PBD organic light-emitting diodes. Appl Surf Sci 253:4025View ArticleGoogle Scholar
- Yi KF, Cheng LL, Wen CC (2011) New random copolymers with pendant carbazole donor and 1,3,4-oxadiazole acceptor for high performance memory device applications. J Mater Chem 21:4778View ArticleGoogle Scholar
- Wonsang K, Byungcheol A, Dong MK, Yong GK, Suk GH, Youngkyoo K, Hwajeong K, Moonhor R (2011) Morphology-dependent electrical memory characteristics of a well-defined brush polymer bearing oxadiazole-based mesogens. J Phys Chem C 115:19355View ArticleGoogle Scholar
- Kyungtae K, Yi KF, Wonsang K, Seungmoon P, Wen CC, Moonhor R (2013) Tunable electrical memory characteristics of brush copolymers bearing electron donor and acceptor moieties. J Mater Chem C 1:4858Google Scholar
- Dong YY, Tae WK, Sang WK (2013) Effect of the ZnS shell layer on the charge storage capabilities of organic bistable memory devices fabricated utilizing CuInS2-ZnS core-shell quantum dots embedded in a poly(methylmethacrylate) layer. Thin Solid Films 544:433View ArticleGoogle Scholar
- Bipul B, Avijit C, Manik KS, Manisree M, Biswanath M (2013) Electric field induced tunable bistable conductance switching and the memory effect of thiol capped CdS quantum dots embedded in poly(methyl methacrylate) thin films. J Mater Chem C 1:1211View ArticleGoogle Scholar
- Ramana CHVV, Moodely MK, Kannan V, Maity A, Jayaramudu J, Clarke W (2012) Fabrication of stable low voltage organic bistable memory device. Sensors and Actuators B 161:684View ArticleGoogle Scholar
- Bipul B, Avijit C, Biswanath M (2013) Tuning of electrical conductivity and hysteresis effect in poly(methyl methacrylate)-carbon nanotube composite films. RSC Adv 3:3325View ArticleGoogle Scholar
- Chao XW, Fu SL, Tai LG (2014) Formation and carrier transport properties of single-layer grapheme/poly(methyl methacrylate) nanocomposite for resistive memory application. Vacuum 101:246View ArticleGoogle Scholar
- Xiao MW, Wei GX, Jian BX (2014) Graphene based nonvolatile memory devices. Adv Mater 26:5496View ArticleGoogle Scholar
- Shengli Q, Hiroki I, Lili L, Stephan I, Wenping H, Eiji Y (2013) Electrical switching behavior of a  fullerene-based molecular wire encapsulated in a syndiotactic poly(methacrylate) Helical cavity. Angew Chem 125:1083View ArticleGoogle Scholar
- Min HL, Jae HJ, Jae HS, Tae WK (2011) Electrical bistabilities and stabilities of organic bistable devices fabricated utilizing [6,6]-phenyl-C85 butyric acid methyl ester blended into a polymethyl methacrylate layer. Org Electron 12:1341View ArticleGoogle Scholar
- Hanju J, Jieun K, Jung AL, Hye JC, Youn SK (2013) Organic nonvolatile resistive switching memory based on molecularly entrapped fullerene derivative within a diblock copolymer nanostructure. Macromol Rapid Commun 34:355View ArticleGoogle Scholar