Importance of electrical coupling for 2D materials

Orateur : Damien VOIRY (Institut Européen des Membranes, Université de Montpellier, CNRS, ENSCM)

Beyond graphene, semiconducting transition metal dichalcogenides (TMDs) hold promise for optoelectronics1 and electrocatalysis2. Unfortunately their properties are often limited by the existence of high Schottky barrier at the interface with metal contacts. Several TMDs can be found stable with two different phases (also called polytypes), which translates into dramatically different electronic behaviors. In the case of group-6 TMDs (MoX2, WX2, X= S, Se, Te), phase transition from semiconducting 2H phase to metallic 1T phase can be achieved via lithiation. We used this concept of phase engineering to prepare in-plane heterostructures consisting of 1T and 2H regions3. This has allowed us to investigate the importance contact resistance on the electronic and electrocatalytic properties of TMDs4,5. More recently we have developed a novel method to reduce graphene oxide based on short pulses of microwaves6. This enables the preparation of reduced graphene oxide with structure and electronic properties approaching those of pristine graphene. The high quality of the reduction makes microwaved graphene oxide a promising platform for electrocatalysis. Through these two examples, I will discuss the importance of the electrical coupling and contact resistance on the electronic and electrocatalytic performance of 2D materials.

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