Epitaxial Electrodeposition of Cu(111) onto an l-Cysteine Self-Assembled Monolayer on Au(111) and Epitaxial Lift-Off of Single-Crystal-like Cu Foils for Flexible Electronics

Abstract

Functional self-assembled monolayers (SAMs) of thiols on single-crystal metals provide two-dimensional (2D) soft templates for the highly ordered growth of crystalline materials. An epitaxial Cu(111) film is electrodeposited on a SAM of the amino acid l-cysteine on Au(111). Epitaxy is confirmed, with Cu(111) following the Au(111) in-plane and out-of-plane orientations with a small amount of twinned [511] orientation, which is shown by X-ray analysis. The mismatch between Cu(111) and the Au(111) substrate is −11.37%. This mismatch is lowered to −0.29% by forming a coincident site lattice in which nine unit meshes of Cu coincide with eight unit meshes of Au. Defect-mediated and coordination-controlled electrodeposition mechanisms are illustrated as two possible deposition mechanisms. The carboxylic (−COOH) and amine (−NH2) functional groups of the l-cysteine molecule are shown to be crucial for the epitaxy of Cu because a 1-butanethiol SAM on Au(111) which has no functional groups yields a textured film with no in-plane order. The (√3 × √3)R30° surface structure of l-cysteine SAM and the c(4 × 2) surface structure of 1-butanethiol SAM on Au(111) are discussed. A 3D model of the Cu lattice on the l-cysteine SAM on Au(111) is proposed. A possible coordination to Cu is shown, which facilitates the epitaxial nucleation and 2D growth of Cu. The Cu(111) films have potential as a substrate for catalysts for CO2 reduction, photovoltaic devices, spintronic devices, and high-temperature superconductors. Direct epitaxial lift-off of the Cu film without etching gives a single-crystal-like Cu(111) foil. The Cu(111) foil exhibits a low resistivity of 3.75 × 10–8 Ω·m and good bending stability, showing only a 12% increase in resistance after 104 bending cycles. Cu(111) foils can be utilized as inexpensive, highly ordered, and conductive substrates for flexible electronics such as wearable solar cells, sensors, and flexible displays. Here, we show an example by electrodepositing epitaxial cuprous oxide on a Cu(111) foil.

Epitaxial Single-Domain Cu-BTC Metal–Organic Framework Thin Films and Foils by Electrochemical Conversion of Cuprous Oxide

“…The electrodeposited ordered Cu 2 O films could prove to be a low-cost and easily prepared precursor for the fabrication of ordered MOF films on a large scale. Cu-BTC films with a thickness about 740 nm can be produced on Cu 2 O/Au or on Au by a complete conversion without the detachment problem that usually occurs in the electrochemical oxidation of Cu metal to Cu-BTC . We also demonstrated a pathway for epitaxial lift-off of Cu-BTC foils that may provide a path to produce membranes for gas separation and selective sensing.…”

“…Cu-BTC films with a thickness about 740 nm can be produced on Cu 2 O/Au or on Au by a complete conversion without the detachment problem that usually occurs in the electrochemical oxidation of Cu metal to Cu-BTC. 31 We also demonstrated a pathway for epitaxial lift-off of Cu-BTC foils that may provide a path to produce membranes for gas separation and selective sensing. ■ ASSOCIATED CONTENT…”

“…Electrochemical epitaxy including electrodeposition and electro-conversion is a low-cost and scalable technique for growing highly ordered thin films. − The conventional electrochemical method using Cu metal as the precursor can only produce polycrystalline Cu-BTC films by anodic dissolution–reprecipitation . Textured Cu-BTC films with only out-of-plane order can be produced by layer-by-layer liquid phase epitaxy using a surface-functionalized Si or Au substrate by functional groups (such as −COOH or −OH).…”

Epitaxial Electrodeposition of Hole Transport CuSCN Nanorods on Au(111) at the Wafer Scale and Lift-off to Produce Flexible and Transparent Foils

“…X-ray diffraction patterns, pole figures, and azimuthal scans were run on a high-resolution Philips X'Pert Materials Research diffractometer using the accessories and procedures outlined in our previous report. 43 SEM was done on a FEI Helios Nanolab microscope, and TEM was done on a FEI Tecnai F20 microscope.…”

Structure, Stability, Properties, and Application of Atomically Thin Coinage Metal Flatland in Graphene Pore: A Density Functional Theory Calculation

“…A novel approach of stabilizing the freestanding metal layers inside the mechanically rigid support such as graphene is also taken. [ 45–48 ] Formation of 2D CuO patch in bilayered graphene (BLG) pore is experimentally observed and characterized by TEM analysis. Further, the same study also reveals that 2D CuO patch found in confinement of BLG exhibits a stable antiferromagnetic behavior.…”