# Upconverted electroluminescence via Auger scattering of interlayer excitons in van der Waals heterostructures

## TL;DR

This paper demonstrates that in van der Waals heterostructures, high-density interlayer excitons can undergo Auger processes leading to upconverted electroluminescence, revealing new pathways for light emission control.

## Contribution

It introduces the observation of upconverted electroluminescence via Auger scattering in WSe₂/MoS₂ heterostructures, highlighting the role of non-radiative processes at high exciton densities.

## Key findings

- Interlayer excitons are tunable by electric field.
- Auger processes enable energy upconversion in electroluminescence.
- Suppression of radiative recombination enhances Auger effects.

## Abstract

The intriguing physics of carrier-carrier interactions, which likewise affect the operation of light emitting devices, stimulate the research on semiconductor structures at high densities of excited carriers, a limit reachable at large pumping rates or in systems with long-lived electron-hole pairs. By electrically injecting carriers into WSe$_2$/MoS$_2$ type-II heterostructures which are indirect in real and k-space, we establish a large population of typical optically silent interlayer excitons. Here, we reveal their emission spectra and show that the emission energy is tunable by an applied electric field. When the population is further increased by suppressing the radiative recombination rate with the introduction of an hBN spacer between WSe$_2$ and MoS$_2$, Auger-type and exciton-exciton annihilation processes become important. These processes are traced by the observation of an up-converted emission demonstrating that excitons gaining energy in non-radiative Auger processes can be recovered and recombine radiatively.