Tunable two-dimensional interfacial coupling in molecular heterostructures

Abstract

Two-dimensional van der Waals heterostructures are of considerable interest for the next generation nanoelectronics because of their unique interlayer coupling and optoelectronic properties. Here, we report a modified Langmuir–Blodgett method to organize two-dimensional molecular charge transfer crystals into arbitrarily and vertically stacked heterostructures, consisting of bis(ethylenedithio)tetrathiafulvalene (BEDT–TTF)/C60 and poly(3-dodecylthiophene-2,5-diyl) (P3DDT)/C60 nanosheets. A strong and anisotropic interfacial coupling between the charge transfer pairs is demonstrated. The van der Waals heterostructures exhibit pressure dependent sensitivity with a high piezoresistance coefficient of −4.4 × 10−6 Pa−1, and conductance and capacitance tunable by external stimuli (ferroelectric field and magnetic field). Density functional theory calculations confirm charge transfer between the n-orbitals of the S atoms in BEDT–TTF of the BEDT–TTF/C60 layer and the π* orbitals of C atoms in C60 of the P3DDT/C60 layer contribute to the inter-complex CT. The two-dimensional molecular van der Waals heterostructures with tunable optical–electronic–magnetic coupling properties are promising for flexible electronic applications.

Light-induced dilation in nanosheets of charge-transfer complexes

“…S3). This suggests that CT is occurring between the n orbitals of the S atoms in DBTTF and the π*-orbitals of the C atoms in C 60 , as found previously for similar complexes (20)(21)(22). The PDOS shows the significant density of C p states in the HOMO of DBTTF, supporting the possibility of π to π* transitions between DBTTF and C 60 .…”

“…An energy cutoff of 30 Ry was used for truncating the plane-wave basis set to represent wave functions. The parameters used in the work give excellent results for the similar complexes studied in our earlier work (20,21). The structures were relaxed until the magnitude of the Hellman-Feynman force on each ion was smaller than 0.03 eVÅ −1 .…”

Preparation Engineering of Two-Dimensional Heterostructures via Bottom-Up Growth for Device Applications

“…At this point, bottom-up growth as a versatile 2D material integration platform was available to construct polymers in two dimensions. Moreover, the enhancement of carrier mobility in the graphene/2DP HS-based FET devices, the ambipolar charge transport in polymer/MoS 2 VHS-based FETs, and the broad-band fast photoresponse in the specific polymer/polymer VHS manifested the prospect of 2DP-based HSs in device applications. With the preparations, tunable structures, properties of 2DPs, and the tempting application prospect of HSs, assembling 2DP-based HSs is imperative and promising via bottom-up integration.…”

Anisotropic Magnetoelectric Coupling and Cotton–Mouton Effects in the Organic Magnetic Charge-Transfer Complex Pyrene–F4TCNQ

“…19,20 For example, in (BEDT-TTF) 2 C 60 , which is a spin−charge converter for energy harvesting, spin information can be converted into electrical energy. 21,22 Conversely, an electric field can be applied to control the spin orientation in organic CT complexes for magnetic recording devices. The storage density for perpendicular magnetic recording is three times higher than that for traditional longitudinal recording.…”

“…Generally, in organic CT complexes, the donor and acceptor components can be stabilized through noncovalent bonding interactions. − Such a strategy has been widely used to form ordered one-, two-, or three-dimensional (1D, 2D, or 3D) CT networks. ,, More importantly, these long-range supramolecular ordering interactions play a key role to guide polar dimerization and spin density waves within tightly packed CT lattices, which could provide a promising pathway to endow these materials with room-temperature ferroelectric or ferromagnetic properties. , For example, in (BEDT-TTF) 2 C 60 , which is a spin–charge converter for energy harvesting, spin information can be converted into electrical energy. , Conversely, an electric field can be applied to control the spin orientation in organic CT complexes for magnetic recording devices. The storage density for perpendicular magnetic recording is three times higher than that for traditional longitudinal recording. , In other words, the magnetoelectric coupling effect in perpendicular multiferroic recording devices can be strongly anisotropic.…”