Large conductance switching and memory effects in organic molecules for data-storage applications

Abstract

We have observed a large electrical conductance switching (ON:OFF ratio=105) in single-layer sandwich structures based on organic molecules at room temperature. The switching devices showed an associated memory effect for data-storage applications. We could write or erase a state and read it for many cycles. In switching devices, the active semiconductor retained its high conducting state until a reverse voltage erased it. A high conducting state arose due to restoration of conjugation in the molecule via electroreduction. Such a high ON–OFF ratio in a single layer sandwich structure, as compared to contemporary switching devices, is due to low off-state leakage current. The concept of conjugation restoration has been verified in supramolecular structures by adding donor groups to the molecule, which resulted in increased off-state current and hence lower ON–OFF ratio. Our work set a generalized example of selecting organic molecules to obtain higher ON–OFF ratio in molecular switching devices.

Resistive switching of rose bengal devices: A molecular effect?

“…Furthermore, the magnitude of the currents shown here is higher than observed by Bandyopadhyay and Pal. 13 They also observed switching in rose bengal devices contacted by different top electrodes, e.g., mercury top electrodes, 16 which hints that the effect they observed has a different origin. However, the switching effect observed in our devices is a more general mechanism which may be in operation in other molecular devices also.…”

“…This switching behavior is similar to the switching behavior of rose bengal devices described by Jakobsson et al 17 but shows significantly larger currents than the switching shown by Bandyopadhyay and Pal. 13 For later applications, the switching speed of the devices is of fundamental interest. The frequency dependence of the switching voltages is shown in Table II.…”

“…Recently, layers of rose bengal ͑see Fig. 1͒ have been shown to switch resistively with high R off / R on values ͑with R off resistance in the high resistive state and R on resistance in the low resistive state͒, [12][13][14][15][16] but the switching mechanism is still under discussion. Possible explanations are a change in the electrical conjugation of the rose bengal molecule by electrochemical reduction, 14 a twist of the upper benzene ring, 12 and the formation and breaking of metallic filaments.…”

The role of internal structure in the anomalous switching dynamics of metal-oxide/polymer resistive random access memories

“…Reported switching times vary by orders of magnitude with values ranging from nanoseconds to milliseconds. [23][24][25][26][27][28][29] As seen in Fig. 6, once programmed into the on-state, even low voltages trigger switching in low current capacity filaments, but still show a delay before the maximum current is achieved.…”

Electrical Bistable Characteristics of Organic Charge Transfer Complex for Memory Device Applications

“…Recently, considerable attention has been directed toward electrical switching and memory devices which consist of organic materials, polymers and charge transfer complexes with an electrical bistable function [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Memory devices based on organic (polymer) materials have many advantages compared to inorganic memory devices, such as flexibility, simple processing, a low cost, and largearea fabrication via printing technology.…”