Effects of Molecular Combination and Side Groups for Thiophene-Benzene-Based Nanodevices

Abstract

The electron transport properties of thiophene-benzene-based molecules attached to zigzag graphene nanoribbon (ZGNR) electrodes are investigated using density functional theory and the nonequilibrium Green function. The results show that 3,6-(dithiophen-2-yl)benzene has better performance compared to 2,5-diphenylthiophene. Interestingly, both the devices exhibit two negative differential resistance (NDR) peaks while a thiophene or a benzene molecule tethered to ZGNR electrodes shows one NDR peak. Although the side groups −OH, −NO 2 , and −NH 2 controllably repress the transmission and current of 3,6-(dithiophen-2-yl)benzene, the current rectification performance is found because of its asymmetry of molecule structure. Unexpectedly, 2,5-diphenylthiophene system added by a thiophene shows semiconductor behavior under a certain bias region. These results contribute to a deep understanding of the electron transport properties of molecular combination and are valuable for designing molecular devices with excellent and distinctive performance at nanoscale.

Odd‐Even Effects on Transport Properties of Polycyclic Arene Molecular Devices with Decreasing Numbers of Benzene Rings

“…Obviously, the electrostatic potential of the device M1 is significantly asymmetric, leading to large a rectification behavior. Additionally, the carbon atom attached to the molecule and ZGNR electrode on the right hand side has a higher potential drop, indicating that there appears to be a higher barrier at the region which plays an essential role in the electron transport properties . There is a larger current at the positive bias compared to that at the negative bias owing to the reducing potential barrier at the region that the electron transfers are easier from the left ZGNR electrode to the right ZGNR electrode.…”

Effects of Inorganic Substitutions and Different Metal Electrode Materials on Electronic Transport Properties of Organic Molecular Devices

“…Usually, conjugated molecules are expected to enhance the electronic communication on the nanoscale for their delocalized π systems. − Among them, the π-conjugated benzene (C 6 H 6 ) molecule coupled between two electrodes has been widely used as a typical research model for both experimental measurements and theoretical simulations. − In this study, we constructed a series of prototypical organic benzene molecules with groups III–V inorganic substitutions, e.g., N, B, Al, or Ga elements. The electronic structural properties of isolated molecules/clusters and the electronic transport properties of such molecules/clusters coupled between two metal electrodes are simulated.…”