Effect of length on the position of negative differential resistance and realization of multifunction in fused oligothiophenes based molecular device

Abstract

The length modulation of electron transport properties for molecular devices based on fused oligothiophenes has been investigated theoretically using a combination of non-equilibrium Green's functions and first-principles density functional theory. The results show that the lengths of the molecules have a distinct influence on the position of negative differential resistance (NDR) of the molecular devices. By exploring the effect on transmission properties of substituent groups, hexathieno[3,2-b:2',3'-d]thiophene with -NH2 and -NO2 substituents (model L) can be regard as a good candidate of multifunctional molecular device, which shows excellent rectifying performance (the largest rectification ration is 14.3 at 1.2 V) and clear NDR behavior (at 1.4 V).