IISER MOHALI

Abstract of the Talk: Negative differential resistance (NDR) effect has drawn lot of attention for applications in molecular electronics devices. Metal phthalocyanines (MPcs) are considered as promising materials for molecular electronics. MPcs with discrete energy levels have possibility to exhibit NDR effect. Studies were carried out on ultrathin films of nickel (II) 1,4,8,11,15,18,22,25-octabutoxy-29H,31H- phthalocyanine (NiPc(OBu)8) deposited on highly ordered pyrolytic graphite (HOPG) substrate (NiPc(OBu)8/HOPG). Also on ultrathin films of NiPc(OBu)8 on graphene oxide (GO) deposited on HOPG (NiPc(OBu)8/GO/HOPG).
In this talk, we describe the atomic force microscope that can be employed to measure the current-voltage (I-V) characteristics. For conductivity, a platinum (Pt) tip was used that forms Pt/NiPc(OBu)8/HOPG and Pt/NiPc(OBu)8/GO/HOPG junctions. The analysis of the ( I-V ) characteristics show negative differential resistance in both the Pt/NiPc(OBu)8/HOPG and Pt/NiPc(OBu)8/GO/HOPG junctions at room temperature. We find that due to the presence of GO, the features of NDR become more prominent. Also GO causes a shift in NDR voltage towards lower value in the negative bias direction. We have analysed our results to understand the role of GO. The lowering of NDR voltage has the advantage to minimize power consumption in molecular electronics devices.