Large Conductance Switching and Binary Operation in Organic Devices:  Role of Functional Groups

Abstract

We have realized tuning of electronic memory-switching property via functional group modification in solidstate devices. Apart from their large ON/OFF ratio and long memory retention time, solid-state devices sustain repetitive switching between the two ON/OFF states at high frequencies. We have chosen several molecular systems with same backbone structure and tuned ON/OFF ratio from 4 to 300 000 simply by increasing the number of deactivating groups. A key to the large ON/OFF ratio in these devices has been the presence of acceptor groups in the molecules and consequently low OFF state current. We analyzed the appearance of ON state in terms of conjugation restoration of the molecules. A redox active group has been found to be necessary in the molecules for continuous flip-flop between "1" and "0" states for random access memory (RAM) applications.

Enhancement of electrical bistability through semiconducting nanoparticles for organic memory applications

“…The range widened further with the work showing organic memory for data-storage applications (Ma et al 2000;Bandhopadhyay & Pal 2003;Yang et al 2004). Organic memory is manifested owing to electrical bistability of molecules and devices (Donhauser et al 2001;Solak et al 2002;Ssenyange et al 2006).…”

“…This leads to two I -V characteristics with an associated memory phenomenon. Conformation change and/or electroreduction of organic molecules plays a key role in changing the conductivity of the devices (Donhauser et al 2001;Solak et al 2002;Bandhopadhyay & Pal 2003;Ssenyange et al 2006). In devices with soft metals as electrodes, filament formation may occur to yield conductance switching.…”

Resistive switching of rose bengal devices: A molecular effect?

“…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. Similarly, some changes in the electrodes ͑e.g., by oxidation͒ or the interface between the electrode and the molecular film can cause the resistive switching.…”

Absorption Spectra of Natural Dyes and Their Effect on Efficiency of ZnO Based Dye-Sensitized Solar Cells

“…To increase the conversion efficiency of ZnO nanorodbased DSSCs, it would be desirable to eliminate the interface between Indium doped Tin oxide (ITO) and the ZnO nanorods (Pradhan et al 2004, Tsubomura et al1976, Terahara et al 1990and Bandhopadhyay et al 2003. Some researchers have recently taken up this concept by growing ZnO nanorods on a ZnO film using a two-step method.…”