Heterostructures of 2D Materials and Organic Semiconductor Nanolayers

• Applicants: Dr. Bert Nickel; Professor Dr. Andrey Turchanin
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 397373225

This project will integrate 2D materials with newly developed nanolayers of organic semiconductors to create van der Waals heterostructures for applications in electronic and optoelectronic systems. We propose a new approach to integrate nanolayers (5 to10 nm) of organic semiconductors (OSC) with inorganic 2D materials, which could contribute significantly to technological advancement by exploiting the properties of both materials. For practical application of vdWh, large scale preparation of heterostructures without compromising their crystallinity and interface quality is required. So far, the primary challenges lie in the difficulty of preparation of high quality, ordered and uniform ultrathin OSC layers on top of 2D crystals over a large area. To address these challenges, this project will utilize novel methods to fabricate vdWh with 2D materials while retaining their structural integrity and high interface quality. We will develop 5 to 10 nm of OSC that are mechanically stable and transferable by crosslinking and layer transfer methods. Specifically, we will produce pn junctions of OSC and atomically thin CVD grown transition metal dichalcogenides (TMDCs), in a lateral and vertical configuration for demonstration of devices such as diodes and transistors. The employment of a broad choice of OSC materials with p and n type carriers (pentacene, DNTT and epindolidione) will allow us to investigate both type I and type II heterojunctions with 2D TMDC materials (MoS2, WSe2). The pn junctions will be integrated with other 2D materials to form all 2D vdWhs with improved device characteristics. CVD graphene will be used as contact materials to OSC and TMDC, where the band alignment and interface resistance can be controlled with gate voltage by tuning the Schottky barrier. Furthermore, we will integrate the recently developed carbon nanomembranes (CNM) as dielectrics in the vdWh devices. We will utilize our cutting edge expertise in growth, nanofabrication, spectroscopy, optical and electrical transport methods to understand the vdWh heterointerfaces and to develop novel electronic and optoelectronic devices. For basic understanding of vdWhs we plan to use our experience in (synchrotron based) photoemission spectroscopy for characterization of electronic structure, electrical transport measurements for understanding the charge transport properties, optical characterization by photocurrent spectroscopy measurements. These proposed vdWh electronic and optoelectronic devices will allow us to exploit the advantages offered by both 2D materials and OSC: Excellent electrical and optical properties, flexibility, large area and low cost production, atomically flat interfaces, excellent gate control over the junction and a great potential for scalability.

• DFG Programme: Research Grants
• International Connection: Netherlands, Sweden
• Cooperation Partners: Professor Michel P. de Jong, Ph.D.; Professor Sergey Kubatkin