A van der Waals pn heterojunction with organic/inorganic semiconductors

TL;DR

This paper reports the fabrication of hybrid organic/inorganic van der Waals heterojunctions using C8-BTBT and MoS2, demonstrating tunable electronic properties, diode behavior, and photovoltaic responses, expanding potential optoelectronic applications.

Contribution

It introduces a novel hybrid 2D heterostructure with organic/inorganic materials grown via vdW epitaxy, showing controllable interfaces and device functionalities.

Findings

High rectification ratio up to 10^5 at room temperature.

Photovoltaic response with 0.31% efficiency and 22 mA/W photoresponsivity.

Tunable device operation through bias and gate voltages.

Abstract

van der Waals (vdW) heterojunctions formed by two-dimensional (2D) materials have attracted tremendous attention due to their excellent electrical/optical properties and device applications. However, current 2D heterojunctions are largely limited to atomic crystals, and hybrid organic/inorganic structures are rarely explored. Here, we fabricate hybrid 2D heterostructures with p-type dioctylbenzothienobenzothiophene (C8-BTBT) and n-type MoS2. We find that few-layer C8-BTBT molecular crystals can be grown on monolayer MoS2 by vdW epitaxy, with pristine interface and controllable thickness down to monolayer. The operation of the C8-BTBT/MoS2 vertical heterojunction devices is highly tunable by bias and gate voltages between three different regimes: interfacial recombination, tunneling and blocking. The pn junction shows diode-like behavior with rectifying ratio up to 105 at the room temperature. Our devices also exhibit photovoltaic responses with power conversion efficiency of 0.31% and photoresponsivity of 22mA/W. With wide material combinations, such hybrid 2D structures will offer possibilities for opto-electronic devices that are not possible from individual constituents.