Metallic Conductivity in a Two-Dimensional Cobalt Dithiolene Metal–Organic Framework

Abstract

Two-dimensional (2D) metal-organic frameworks (MOFs) have received a great deal of attention due to their relatively high charge carrier mobility and low resistivity. Here we report on the temperature-dependent charge transport properties of a 2D cobalt 2,3,6,7,10,11-triphenylenehexathiolate framework. Variable temperature resistivity studies reveal a transition from a semiconducting to a metallic phase with decreasing temperature, which is unprecedented in MOFs. We find this transition to be highly dependent on the film thickness and the amount of solvent trapped in the pores, with density functional theory (DFT) calculations of the electronic-structure supporting the complex metallic conductivity of the material. These results identify the first experimentally observed MOF that exhibits band-like metallic conductivity.

Structural Engineering of Low‐Dimensional Metal–Organic Frameworks: Synthesis, Properties, and Applications

“…[81] The Young's modulus of the MOF nanosheets is calculated to be 5 GPa. [86][87][88] As a typical example, Cu-CTA nanowire array with conductivity of ≈20 S m −1 for an individual nanowire was grown on carbon paper, and then used as electrode for supercapacitor, which showed an areal capacitance of ≈22 µF cm −2 . Besides, the good flexibility and mechanical properties of LD MOF films opened vast opportunities in the practical applications of air filter and optical devices.…”

“…[175] Using surfactants or small molecule modulators for the synthesis of 2D MOFs may block part of the active sites. [87,88] As a typical example, the Zn/Ni MOF-2 nanosheet-assembled hollow structure was prepared through a surfactant-free solvothermal approach. b) AFM image of the exfoliated Mn-DMS nanosheet, and c) the corresponding height profiles.…”

Metal–Organic Frameworks in Modern Physics: Highlights and Perspectives

“…[30] With semiconducting MOFs, the metallic effect is determined by strong overlapping of the electronic wave functions between metal nodes and ligands, making π-conjugation essential for a metallic nature. [30] With semiconducting MOFs, the metallic effect is determined by strong overlapping of the electronic wave functions between metal nodes and ligands, making π-conjugation essential for a metallic nature.…”

“…[30] With semiconducting MOFs, the metallic effect is determined by strong overlapping of the electronic wave functions between metal nodes and ligands, making π-conjugation essential for a metallic nature. [30] Moreover, MOFs can demonstrate bimodal charge transport: metallic in the plane of the MOF's van der Waals (vdW) layers, and semiconducting normal to these layers. However, the origins of this effect are obscure, as it is observed only with 2D MOFs; [30][31][32][33][34][35] MOFs usually demonstrate semiconducting properties between 170 and 300 K, while they are metals below 130 K, as in a 2D MOF such as cobalt 2,3,6,7,10,11-triphenylenehexathiolate.…”

Demonstration of a Broadband Photodetector Based on a Two‐Dimensional Metal–Organic Framework

“…Though the majority of MOFs are known to be electrical insulators, advances in synthetic approaches over the past decade have revealed several examples of (semi)conductive MOFs, an aspect that allows their use in (opto)electronic applications as an active element. While some works demonstrate their semiconducting behavior, others have revealed them behaving as either metals or semimetals, that is, lacking a bandgap. Among them, graphene‐like MOF analogues, where 2D hexagonal lattices are obtained from trigonal organic ligands coordinated by square‐planar atomic metal nodes, have emerged as a unique sub‐class of electrically conducting materials.…”