Bistable Organic Memory Device with Gold Nanoparticles Embedded in a Conducting Poly(N-vinylcarbazole) Colloids Hybrid

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• 作者：Dong Ick Son ; Dong Hee Park ; Jong Bin Kim ; Ji-Won Choi ; Tae Whan Kim ; Basavaraj Angadi ; Yeonjin Yi ; Won Kook Choi
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：February 10, 2011
• 年：2011
• 卷：115
• 期：5
• 页码：2341-2348
• 全文大小：1085K
• 年卷期：v.115,no.5(February 10, 2011)
• ISSN：1932-7455

文摘

We report on the nonvolatile memory characteristics of a bistable organic memory (BOM) device with Au nanoparticles (NPs) embedded in a conducting poly(N-vinylcarbazole) (PVK) colloids hybrid layer deposited on flexible poly(ethyleneterephthalate) (PET) substrates. Transmission electron microscopy (TEM) images show the Au nanoparticles distributed isotropically around the surface of a PVK colloid. The average induced charge on Au nanoparticles, estimated using the C鈭?i>V hysteresis curve, was large, as much as 5 holes/NP at a sweeping voltage of 卤3 V. The maximum ON/OFF ratio of the current bistability in the BOM devices was as large as 1 脳 10⁵. The cycling endurance tests of the ON/OFF switching exhibited a high endurance of above 1.5 脳 10⁵ cycles, and a high ON/OFF ratio of 10⁵ could be achieved consistently even after quite a long retention time of more than 1 脳 10⁶ s. To clarify the memory mechanism of the hole-mediated bistable organic memory device, the interactions between Au nanoparticles and poly(N-vinylcarbazole) colloids was studied by estimating the density of states and projected density of state calculations using density functional theory. Au atom interactions with a PVK unit decreased the band gap by 2.96 eV with the new induced gap states at 5.11 eV (HOMO, E₀) and LUMO 4.30 eV and relaxed the HOMO level by 0.5 eV (E₁). E₁ at 6.2 eV is very close to the pristine HOMO, and thus the trapped hole in E₁ could move to the HOMO of pristine PVK. From the experimental data and theoretical calculation, it was revealed that a low-conductivity state resulted from a hole trapping at E_o and E₁ states and subsequent hole transportation through Fowler鈭扤ordheim tunneling from E₁ state to Au NPs and/or interface trap states leads to a high conductivity state.