一种新型的有机电双稳薄膜及其极性记忆效应

报道了一种新的高稳定的有机分子(SCN)可以和铜构成具有电双稳态特性的金属有机络合物.由这种材料制成的薄膜,在室温6V电压作用下可以从高阻态转变成低阻态,其跃迁时间小于20ns,并具有极佳的热稳定性.因此可望用于制作电子器件,如一次写入存储器(WORM)等.进一步的研究还发现,在适当的工艺条件下,SCN能够与Cu和Al一起构成Cu-SCN-Al结,这种结具有极性记忆效应,即只能被单向驱动.     

具有非易失存储功能的可逆有机电双稳器件

报道一种能够在室温下具有可逆电双稳特性，并实现非易失信息存储功能的有机薄膜器件。器件为简单的三层结构，Al/HPYM/Ag，HPYM为一种有机分子材料，通过真空热蒸发法制成薄膜作为信息存储介质。该器件可通过正向及反向电压脉冲的激发而实现高阻态（“0”态）、低阻态（“1”态）的转变，相当于信号的写入和擦除。当外电场撤除时，其状态信息可以长时间保持，并且被小电压脉冲读取，两种导电态的阻值比约为10^5。     

Wrapping Graphene Sheets Around Organic Wires for Making Memory Devices

Hybrids of organic semiconductors and graphene can generate a whole new class of materials with enhanced properties. A simple solution‐phase route to synthesize a hybrid material made of organic nanowires and graphene oxide (GO) sheets is demonstrated by sonicating tetracene molecules and GO together in diluted fuming nitric acid. The self‐assembled tetracene‐derived organic wires become encapsulated by GO sheets during the reaction to produce an interconnected, one‐dimensional/two‐dimensional lamellar film. Memory devices fabricated using the hybrid film as the sandwiched layer between aluminum electrodes exhibit excellent electrical bistability. The charge retention properties are attributed to charge transfer and a charge‐trapping/detrapping mechanism operational at the interfaces and isolated matrices of the GO–tetracene hybrid.     

High‐Performance Flexible Organic Nano‐Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles

Nano‐floating gate memory (NFGM) devices are transistor‐type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe₂O₄) nanoparticles (NPs) as charge trap sites and pentacene as a p‐type semiconductor. Monodisperse CoFe₂O₄ NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle–particle interactions. CoFe₂O₄ NP‐based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I_on/I_off) of ≈2.98 × 10³_, and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe₂O₄ NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high‐performance organic memory devices.     

A High‐Performance Optical Memory Array Based on Inhomogeneity of Organic Semiconductors

Organic optical memory devices keep attracting intensive interests for diverse optoelectronic applications including optical sensors and memories. Here, flexible nonvolatile optical memory devices are developed based on the bis[1]benzothieno[2,3‐d;2′,3′‐d′]naphtho[2,3‐b;6,7‐b′]dithiophene (BBTNDT) organic field‐effect transistors with charge trapping centers induced by the inhomogeneity (nanosprouts) of the organic thin film. The devices exhibit average mobility as high as 7.7 cm² V^?1 s^?1, photoresponsivity of 433 A W^?1, and long retention time for more than 6 h with a current ratio larger than 10⁶. Compared with the standard floating gate memory transistors, the BBTNDT devices can reduce the fabrication complexity, cost, and time. Based on the reasonable performance of the single device on a rigid substrate, the optical memory transistor is further scaled up to a 16 × 16 active matrix array on a flexible substrate with operating voltage less than 3 V, and it is used to map out 2D optical images. The findings reveal the potentials of utilizing [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) derivatives as organic semiconductors for high‐performance optical memory transistors with a facile structure. A detailed study on the charge trapping mechanism in the derivatives of BTBT materials is also provided, which is closely related to the nanosprouts formed inside the organic active layer.     

热致形状记忆聚合物的形状记忆机理与性能研究进展

主要分析了热致形状记忆聚合物聚集态结构与形状记忆性能之间的关系(聚合物的聚集态结构大致可以分为3种:可逆相和固定相均为不定形结构;可逆相为不定形结构,固定相为结晶结构;可逆相为结晶结构,固定相为不定形结构)。总结了聚集态结构对转变温度、存储模量、形状固定率/回复率、回复应力和回复速率等的影响。