Production of Ultra-Thin and High-Quality Nanosheet Networks via Layer-by-Layer Assembly at Liquid-Liquid Interfaces

TL;DR

This paper presents a liquid-liquid interface assembly method to produce ultra-thin, high-quality nanosheet networks with low junction resistance, achieving record mobility and conductivity in graphene and MoS2 for printed electronics.

Contribution

It introduces a novel liquid-interface deposition process that significantly reduces junction resistance, enabling high-performance nanosheet networks with potential applications in printed electronics.

Findings

Achieved low RJ/RNS ratios of 0.5 for graphene and 0.2 for MoS2.

Demonstrated record mobility of 30 cm²/Vs in MoS2 networks.

Produced networks with conductivity up to 5×10^4 S/m.

Abstract

Solution-processable 2D materials are promising candidates for a range of printed electronics applications. Yet maximising their potential requires solution-phase processing of nanosheets into high-quality networks with carrier mobility ({\mu}Net) as close as possible to that of individual nanosheets ({\mu}NS). In practise, the presence of inter-nanosheet junctions generally limits electronic conduction, such that the ratio of junction resistance (RJ) to nanosheet resistance (RNS), determines the network mobility via . Hence, achieving RJ/RNS<1 is a crucial step for implementation of 2D materials in printed electronics applications. In this work, we utilise an advanced liquid-interface deposition process to maximise nanosheet alignment and network uniformity, thus reducing RJ. We demonstrate the approach using graphene and MoS2 as model materials, achieving low RJ/RNS values of 0.5 and 0.2, respectively. The resultant graphene networks show a high conductivity of {\sigma}Net = 5 \times 104 S/m while our semiconducting MoS2 networks demonstrate record mobility of {\mu}Net = 30 cm2/Vs, both at extremely low network thickness (tNet <10 nm). Finally, we show that the deposition process is compatible with non-layered quasi-2D materials such as silver nanosheets (AgNS), achieving network conductivity close to bulk silver for networks <100 nm thick. We believe this work is the first to report nanosheet networks with RJ/RNS<1 and serves to guide future work in 2D materials-based printed electronics.