Two-dimensional Quasi-Freestanding Molecular Crystals for High-Performance Organic Field-Effect Transistors

TL;DR

This paper reports the growth of high-quality, monolayer molecular crystals on 2D substrates, enabling high-performance organic transistors with record-high mobility and low voltage, advancing 2D molecular electronics.

Contribution

It introduces a scalable van der Waals epitaxy method to produce 2D molecular crystals with controlled thickness and high device performance, a significant step forward in molecular electronics.

Findings

Monolayer molecular crystals grown on 2D substrates.

Record-high carrier mobility of 10 cm²V⁻¹s⁻¹ in transistors.

Low saturation voltage around 1V.

Abstract

Two-dimensional atomic crystals are extensively studied in recent years due to their exciting physics and device applications. However, a molecular counterpart, with scalable processability and competitive device performance, is still challenging. Here, we demonstrate that high-quality few-layer dioctylbenzothienobenzothiophene molecular crystals can be grown on graphene or boron nitride substrate via van der Waals epitaxy, with precisely controlled thickness down to monolayer, large-area single crystal, low process temperature and patterning capability. The crystalline layers are atomically smooth and effectively decoupled from the substrate due to weak van der Waals interactions, affording a pristine interface for high-performance organic transistors. As a result, monolayer dioctylbenzothienobenzothiophene molecular crystal field-effect transistors on boron nitride show record-high carrier mobility up to 10cm2V-1s-1 and aggressively scaled saturation voltage around 1V. Our work unveils an exciting new class of two-dimensional molecular materials for electronic and optoelectronic applications.