Semiconducting to Metallic Electronic Landscapes in Defects‐Controlled 2D π‐d Conjugated Coordination Polymer Thin Films

Abstract

Two‐dimensional coordination polymers (2DCPs) have been predicted to exhibit exotic properties such as superconductivity, topological insulating behavior, catalytic activity, and superior ion transport for energy applications; experimentally, these materials have fallen short of their expectation due to the lack of synthesis protocols that yield continuous, large crystallite domains, and highly ordered thin films with controllable physical and chemical properties. Herein, the fabrication of large‐area, highly ordered 2DCP thin films with large crystallite domains using chemical vapor deposition (CVD) approaches is described. It is demonstrated that defects and the packing motifs of 2DCP thin films may be controlled by adjusting the vapor–vapor and vapor–solid interactions of the metal and organic linker precursors during the CVD fabrication process. Such control allows for the fabrication of defects‐controlled 2DCP thin films that show either semiconducting or metallic behavior. The findings provide the first demonstration of tuning the electrical properties of sub 100 nm‐thick continuous 2DCP thin films by controlling their electronic landscape through defect engineering. As such, it is determined that large‐area, highly ordered 2DCP thin films may undergo a semiconducting to metallic transition that is correlated to changes in morphology, crystalline domain sizes, crystallite orientation, defect interactions, and electronic structure.

Electrically Conductive Metal–Organic Framework Thin Film‐Based On‐Chip Micro‐Biosensor: A Platform to Unravel Surface Morphology‐Dependent Biosensing

“…The Cu 2p 3/2 peak near 931.8 eV represents the Cu atoms (s‐Cu) in Cu‐BHT structure binding with four S atoms, while the wide peak near 933.2 eV can be attributed to the Cu atom (ts‐Cu) in the crystal defects, binding with two S atoms (Figure 5e). [ 27 ] As shown in Figure 5b, the bottom‐side surface of the Cu‐BHT film clearly had a higher percentage of ts‐Cu (51.32%) than that in the up‐side surface (35.24%). Cu LMM Auger spectra were used to clarify the valence states of the Cu on surface of the Cu‐BHT film.…”

Two-dimensional conjugated metal–organic frameworks (2D c-MOFs): chemistry and function for MOFtronics

“…In another example, the highly crystalline Cu 3 (HTB) film exhibits a conductivity reaching 2500 S cm À1 , 68 while the conductivity of the one with low crystallinity (according to the X-ray diffraction and transmission electron microscopy analysis) was merely determined to be 1580 S cm À1 . 31,134 In addition, the synthesized M 3 (HIB) 2 (M = Cu, Ni, Co) films were reported as an electrical insulator in the early work from Lahiri et al, 135 which is likely attributed to the low crystallinity in these samples. By comparison, their intrinsic metallicity was confirmed in the highly crystalline bulk samples (M = Cu, Ni) by ultravioletphotoelectron spectroscopy.…”

Evolutionary 2D organic crystals for optoelectronic transistors and neuromorphic computing

“…As a result, we need to create simple and effective organic crystal development methods as well as suitable crystal growth methods to prepare high-quality single crystals. Many preparation strategies have been proposed since the definition of 2D OCs (figure 6) [19,59,69,[75][76][77][78][79]. The procedures can be classified into two groups based on the condition of matter: gas-phase preparation and liquid-phase preparation.…”