Length-independent multifunctional device based on penta-tetra-pentagonal molecule: a first-principles study

Abstract

Recently, a novel sp² hybridized planar two-dimensional carbon allotrope consisting of tetra, penta and octagonal (TPO) rings has attracted much interest. Its quasi-one-dimensional counterpart, the penta-tetra-pentagonal (PTP) molecule chain, can be obtained by carving it from the 2D TPO-carbon structure, and it has also had much attention. Here, we present a first-principles study for the spin-dependent electron transport for model devices which consist of PTP molecule chains with different lengths sandwiching between two semi-infinite zigzag-edged graphene nanoribbon (zGNR) electrodes. By using the non-equilibrium Green’s function formalism in combination with density-functional theory, a length-independent, stable and perfect spin-filtering can be found in these PTP molecules based devices with parallel configuration in electrodes. Further, the coexistence of dual spin-filtering and -rectifying with a high ratio is demonstrated in the device with antiparallel spin configuration in electrodes. Interestingly, a two-state molecular conformational switch can be realized by mechanically rotating the plane between the PTP molecule chain and zGNR electrodes from coplanar to perpendicular, and the device exhibits a substantially large current modulation, and the ON/OFF switching ratio can reach up to 10³ within the considered bias window. Furthermore, the physical mechanisms are revealed and discussed by presenting the transmission spectra at the Fermi energy in combination with the separation of local device density of states at the Fermi level. All these theoretical predictions might trigger a new avenue to expand the application of carbon allotrope materials in nanoelectronics.