Effect of Functional Group on Electrical Switching Behaviour of an Imidazole Derivative in Langmuir-Blodgett Film

TL;DR

This study investigates how different functional groups attached to an imidazole derivative influence its electrical switching behavior in Langmuir-Blodgett films, revealing the crucial role of the benzyl group in bipolar resistive switching.

Contribution

The paper demonstrates the impact of the benzyl group on the bipolar switching behavior of imidazole-based LB films, highlighting the importance of functional group modification for organic electronic devices.

Findings

60-layer LB films exhibit bipolar resistive switching.

Presence of benzyl group enables bipolar switching, absence does not.

Reduction-oxidation processes are responsible for switching behavior.

Abstract

Here we report the design and synthesis of an imidazole derivative namely 1-benzyl-2,4,5-triaryl imidazole and its switching behaviour assembled onto Langmuir-Blodgett films. Monolayer characteristic of imidazole at the air-water interface has been studied by surface pressure vs area per molecule isotherm, hysteresis analysis and insitu Brewster Angle Microscopy . These studies indicated the formation of stable floating Langmuir film at the water subphase. Atomic Force Microscopy investigation confirmed the successful deposition of the Langmuir film onto solid substrate. Device consisted of 60 layers LB films of imidazole showed resistive bipolar switching behaviour irrespective of the first applied bias voltage polarity. Observed bipolar switching has been explained in terms of reduction oxidation process. Due to the presence of strong reducible group C double bond N in the imidazole core, reduction oxidation process takes place easily during bias. Presence of sharp reduction and oxidation peaks in the Cyclic Voltammetry measurement of 2 also supported this hypothesis. Presence of benzyl group with the imidazole core played the crucial rule in the reduction oxidation process and hence the switching behaviour. When benzyl group was replaced by a H then bipolar switching was not observed. In that case oxidizable group NH opposed the reduction process during bias. This type of bipolar switching is very promising for future technological applications in organic electronics.