Twist Angle-Dependent Molecular Intercalation and Sheet Resistance in Bilayer Graphene

Abstract

Bilayer graphene (BLG) has a two-dimensional (2D) interlayer nanospace that can be used to intercalate molecules and ions, resulting in a significant change of its electronic and magnetic properties. Intercalation of BLG with different materials, such as FeCl3, MoCl5, Li ions, and Ca ions, has been demonstrated. However, little is known about how the twist angle of the BLG host affects intercalation. Here, by using artificially stacked BLG with controlled twist angles, we systematically investigated the twist angle dependence of intercalation of metal chlorides. We discovered that BLG with high twist angles of >15° is more favorable for intercalation than BLG with low twist angles. Density functional theory calculations suggested that the weaker interlayer coupling in high twist angle BLG is the key for effective intercalation. Scanning transmission electron microscope observations revealed that co-intercalation of AlCl3 and CuCl2 molecules into BLG gives various 2D structures in the confined interlayer nanospace. Moreover, before intercalation we observed a significantly lower sheet resistance in BLG with high twist angles (281 ± 98 Ω/□) than that in AB stacked BLG (580 ± 124 Ω/□). Intercalation further decreased the sheet resistance, reaching values as low as 48 Ω/□, which is the lowest value reported so far for BLG. This work provides a twist angle-dependent phenomenon, in which enhanced intercalation and drastic changes of the electrical properties can be realized by controlling the stacking angle of adjacent graphene layers.

Graphene-inspired quasi-two-dimensional gold films

“…Thus, Figure 5 shows that our quasi-2D gold films are perfect candidates for flexible and transparent electrodes in optoelectronic applications. 23,41,42 , ITO 14,42 , and twisted graphene 43…”

“…Figure 5| Optoelectronic properties of quasi-2D gold. (a) Sheet resistance and transmittance at λ = 550 nm of quasi-2D gold in comparison with other ultrathin films23,41,42 , ITO14,42 , and twisted graphene43 . The inset zooms the transmittance-conductivity…”

Control of rotation angles of multilayer graphene on SiC (000 1‾ ) by substrate off-direction and angle

“…In particular, TBG exhibits superconductivity at a rotation angle of 1.1 • , which is called the magic angle [13,14]. It has also been reported that the rotation angle between graphene layers affects their optical properties [15,16], carrier mobility [17], and degree of molecular intercalation [18]. Thus, control of the rotation angle of graphene and other 2D materials is important for the development of their physics and applications.…”