Isoreticular two-dimensional magnetic coordination polymers prepared through pre-synthetic ligand functionalization

Chemical functionalization is a powerful approach to tailor the physical and chemical properties of two-dimensional materials, increase their processability and stability, tune their functionalities and, even, create new 2D materials. This is typically achieved through post-synthetic functionalization by anchoring molecules on the surface of an exfoliated 2D crystal, but it inevitably alters the long-range structural order of the material. Here we present a pre-synthetic approach that allows the isolation of crystalline, robust, and magnetic functionalized monolayers of coordination polymers. A series of five isoreticular layered magnetic coordination polymers based on Fe(II) centres and different benzimidazole derivatives (bearing a Cl, H, CH3, Br or NH2 side group) were first prepared. On mechanical exfoliation, 2D materials are obtained that retain their long-range structural order and exhibit good mechanical and magnetic properties. This combination, together with the possibility to functionalize their surface at will, makes them good candidates to explore magnetism in the 2D limit and to fabricate mechanical resonators for selective gas sensing

Chemical Vapor Deposition of Boron Nitride Nanosheets on Metallic Substrates via Decaborane/Ammonia Reactions

A method involving the reaction of the commercially available polyborane decaborane with ammonia, that provides a simple chemical vapor deposition (CVD) route for the efficient formation of boron nitride nanosheets (BNNS) on either polycrystalline Ni or Cu foil, was reported. The metal foils were annealed in the CVD system to 1000°C under a combined flow of nitrogen and hydrogen. The AFM analyses in the tapping mode indicate that the films grown on Ni are approx 2 nm thick on average, corresponding to only a few layers of BN graphene. The results show that a fine-tuning of the decaborane/ammonia pressure and growth conditions may likewise result in the controlled growth of regular polygonal BNNS structures on metallic substrates. The Raman spectra of the BNNS confirm the formation of h-BN, showing the characteristic vibration at approx 1366 cm -1 with an intensity that increased as the film thickness is increased

Solution-processed MoS2/organolead trihalide perovskite photodetectors

202308 bcvcAccepted ManuscriptOthersThe Shenzhen Science and Technology Innovation CommitteePublishe

Metallic 1T phase source/drain electrodes for field effect transistors from chemical vapor deposited MoS2

Two dimensional transitionmetal dichalcogenides (2D TMDs) offer promise as optoelectronic materials due to their direct band gap and reasonably good mobility values. However, most metals form high resistance contacts on semiconducting TMDs such as MoS2. The large contact resistance limits the performance of devices. Unlike bulk materials, low contact resistance cannot be stably achieved in 2D materials by doping. Here we build on our previous work in which we demonstrated that it is possible to achieve low contact resistance electrodes by phase transformation. We show that similar to the previously demonstrated mechanically exfoliated samples, it is possible to decrease the contact resistance and enhance the FET performance by locally inducing and patterning the metallic 1T phase of MoS2 on chemically vapor deposited material. The device properties are substantially improved with 1T phase source/drain electrodes