Light-emitting diodes by bandstructure engineering in van der Waals heterostructures

TL;DR

This paper demonstrates the creation of tunable light-emitting diodes using precisely engineered van der Waals heterostructures of 2D materials, achieving significant efficiency and flexibility for advanced optoelectronic applications.

Contribution

It introduces a novel method of bandstructure engineering in 2D heterostructures to develop efficient, tunable, and flexible LEDs with atomic-scale precision.

Findings

Achieved nearly 10% quantum efficiency in 2D material-based LEDs.

Emission wavelength can be tuned by selecting different 2D semiconductors.

Devices are compatible with flexible and transparent substrates.

Abstract

The advent of graphene and related 2D materials has recently led to a new technology: heterostructures based on these atomically thin crystals. The paradigm proved itself extremely versatile and led to rapid demonstration of tunnelling diodes with negative differential resistance, tunnelling transistors5, photovoltaic devices, etc. Here we take the complexity and functionality of such van der Waals heterostructures to the next level by introducing quantum wells (QWs) engineered with one atomic plane precision. We describe light emitting diodes (LEDs) made by stacking up metallic graphene, insulating hexagonal boron nitride (hBN) and various semiconducting monolayers into complex but carefully designed sequences. Our first devices already exhibit extrinsic quantum efficiency of nearly 10% and the emission can be tuned over a wide range of frequencies by appropriately choosing and combining 2D semiconductors (monolayers of transition metal dichalcogenides). By preparing the heterostructures on elastic and transparent substrates, we show that they can also provide the basis for flexible and semi-transparent electronics. The range of functionalities for the demonstrated heterostructures is expected to grow further with increasing the number of available 2D crystals and improving their electronic quality.