Electrical bistability in a composite of polymer and barium titanate nanoparticles (original) (raw)
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Non-volatile memory device-using a blend of polymer and ferroelectric nanoparticles
Journal of Optoelectronics and Advanced Materials
In recent years, the interest in the application of organic materials in electronic devices (light emitting diodes, field effect transistors, solar cells), has shown a rapid increase. A new family of organic electronic device is organic memory device. These devices, based on a thin film of nano-sized particles and small molecules embledded in an organic layer attracted considerable attention. This work presents the polymer memory device which is made of a blend of poly(vinyl acetate) and ferroelectric barium titanate nanoparticles. A polymer blend of polyvinyl acetate and barium titanate (BaTiO 3) nanoparticles was prepared in methanol and spin coated onto a glass substrate marked with thin Al tracks and top contacts were evaporated onto the blend after drying -this resulted in a metal-organic-metal (MOM) structure. The current-voltage (I-V) behaviour of MOM devices shows that the devices can be switched from a high conductivity state to a low conductivity state, by applying an exte...
(Invited) Electrical Conductivity Bistability in Nano-Composite
Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states ("1" and "0") when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the realisation of nonvolatile memory. Nano-composite polymer memory devices comprising of a blend of a polymer and small molecules and/or nanoparticles are investigated. This study is aimed at further understanding the electrical bistability observed in such devices. This work also investigates if an electrical charge can be transferred to gold nano-particles and, between small molecule complexes.
Electrical Conductivity Bistability in Nano-Composite
ECS Transactions
Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states ("1" and "0") when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the realisation of non-volatile memory. Nano-composite polymer memory devices comprising of a blend of a polymer and small molecules and/or nanoparticles are investigated. This study is aimed at further understanding the electrical bistability observed in such devices. This work also investigates if an electrical charge can be transferred to gold nano-particles and, between small molecule complexes.
Organic Electronics, 2014
Bistable nonvolatile memory devices containing two different layers of polymers, viz. MEH-PPV (poly[2-methoxy-5-(2 0-ethyl-hexyloxy)-1,4-phenyl vinylene]) and PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) has been fabricated by a simple spin-coating technique on flexible polyimide (PI) substrates with a structure Al/ MEH-PPV/PEDOT:PSS/Ag-Pd/PI. The current-voltage measurements of the as-fabricated devices showed a nonvolatile electrical bistability with electric field induced charge transfer through the polymer layers and negative differential resistance (NDR) which is attributed to the charge trapping in the MEH-PPV layer. The current ON/OFF ratio between the high-conducting state (ON state) and low-conducting state (OFF state) is found to be of the order of 10 3 at room temperature which is comparable to organic field effect transistor based memory devices. We propose that such an improvement of rectification ratio (ON/ OFF ratio) is caused due to the inclusion of PEDOT:PSS, which serves as a conducting current path for carrier transport; however, NDR is an effect of the trapped charges in the MEH-PPV electron confinement layer. The device shows excellent stability over 10 4 s without any significant degradation under continuous readout testing in both the ON and OFF states. The carrier transport mechanism of the fabricated organic bistable device has been explained on the basis of different conduction mechanisms such as thermionic emission, space-charge-limited conduction, and Fowler-Nordheim tunneling. A band diagram is proposed to explain the charge transport phenomena. These bilayer structures are free from the drawbacks of the single organic layer based memory devices where the phase separation between the nanoparticles and polymers leads to the degradation of device stability and lifetime.
Memory performance and retention of an all-organic ferroelectric-like memory transistor
IEEE Electron Device Letters, 2000
We have built a nonvolatile memory field-effect transistor (FET)-based on organic compounds. The gate-insulating polymer features ferroelectric-like characteristics when spun from solution into an amorphous phase. Thus, the memory transistor is built using techniques developed for organic transistors without requiring high temperature annealing steps. The memory exhibits channel resistance modulations and retention times close in performance to inorganic ferroelectric FETs (FEFETs), yet at a fraction of the cost.
A New Nonvolatile Bistable Polymer-Nanoparticle Memory Device
IEEE Electron Device Letters, 2007
In this letter, we demonstrate a new organic bistable nonvolatile memory device that is adopting polymer-chainstabilized gold (Au) nanoparticles in a host polymer as a memory active layer. In this letter, the Au nanoparticles are well dispersed in the host polymer so as to enhance stability of memory devices. Current-voltage characteristics show that the device switches from an initial low-conductivity state to a high-conductivity state upon applying an external electric field at room temperature. This memory can be switched ON and OFF for over 150 times without an apparent performance degradation. In addition, the memory state can retain for over 36 000 s in air. This memory device is thus considered to be a suitable candidate for flexible electronics applications.
IEEE Transactions on Electron Devices, 2000
Resistive switches have been fabricated using a phase-separated blend film of ferroelectric random copolymer poly(vinylidene fluoride-co-trifluoroethylene) with the organic semiconductor regio-irregular poly(3-hexylthiophene) (rir-P3HT). Spin-coated blend films have been contacted with symmetrical Ag top and Ag bottom electrodes, yielding switching diodes. The ferroelectric polarization modulates the injection barrier, yielding an injection-limited OFF-state and a space-charge-limited ON-state. To study the effect of depolarization, an additional polyphenylenevinylene-type semiconductor layer with the highest occupied molecular orbital energy that is comparable to that of rir-P3HT has been inserted in the diode stack. When the ad-layer is the injecting contact, the current modulation ratio goes to unity. The origin is a decrease in the effective band bending at the contact with increasing ad-layer thickness. When the counter electrode at the blend interface is the injecting contact, the diode can be switched, but the ON-state is only stable when an electric field that is larger than the coercive field is applied. Upon field removal, the ferroelectric depolarizes, and the current drops to that of an unpoled pristine diode. The depolarization is confirmed by capacitance-voltage and retention time measurements. To realize bistable diodes with excellent retention times, the thickness of the semiconducting wetting layer may not be at most 10 nm. The Netherlands, in 2005 and 2010, respectively. The subject of his Ph.D. thesis was organic nonvolatile ferroelectric memories and opto-electronics. He is currently a Postdoctoral Researcher with the Zernike Institute for Advanced Materials, University of Groningen. His research interests include ferroelectric opto-electronics devices, organic nonvolatile memories, and organic field-effect transistors.