Bandyopadhyay Anirban, Pal Amlan J
Indian Association for the Cultivation of Science, Department of Solid State Physics, Jadavpur, Kolkata 700 032, India.
J Phys Chem B. 2005 Apr 7;109(13):6084-8. doi: 10.1021/jp0452507.
We have studied memory-switching phenomena in terms of impedance spectroscopy in a series of xanthene-class fluorescein molecules. Frequency response studies have revealed that the electronic conduction mechanism was largely tuned by increasing the number of acceptor groups attached to the molecular backbone. In molecules with weak intermolecular interactions, the transition between a low- and a high-conducting state has been associated with a change in bulk resistance and dielectric properties. The devices in the two states remained a parallel combination of a resistor and a capacitor (C(P)-R(P)) network. In devices based on Rose Bengal, which exhibits a strong dipole-dipole interaction due to its acceptor groups, the switching between the states has been modeled as a transition between a C(P)-R(P) network in the off-state and a distributed resistor-capacitor (R-C) line network in the on-state. Instead of isolated clusters, a highly coupled network of reduced Rose Bengal molecules with strong dipole-dipole interaction yielded the high-conducting state. Under a "write-read-erase-read" sequence, the device switched between the two networks reversibly for many cycles.
我们通过阻抗谱研究了一系列呫吨类荧光素分子中的记忆切换现象。频率响应研究表明，通过增加连接到分子主链上的受体基团数量，电子传导机制在很大程度上得到了调节。在分子间相互作用较弱的分子中，低导电态和高导电态之间的转变与体电阻和介电性质的变化有关。这两种状态下的器件保持为电阻器和电容器（C(P)-R(P)）网络的并联组合。在基于玫瑰红的器件中，由于其受体基团表现出强偶极 - 偶极相互作用，状态之间的切换被建模为从关态的C(P)-R(P)网络到开态的分布式电阻 - 电容（R-C）线路网络的转变。具有强偶极 - 偶极相互作用的还原玫瑰红分子的高度耦合网络而非孤立簇产生了高导电态。在“写入 - 读取 - 擦除 - 读取”序列下，器件在两个网络之间可逆地切换了许多循环。
