# Giant Photocurrent Enhancement by Coulomb Interaction in a Single Quantum Dot for Energy Harvesting

## TL;DR

This study demonstrates a giant enhancement in photocurrent in a single quantum dot caused by Coulomb interactions, revealing new insights into energy conversion processes at the nanoscale for improved solar cell efficiency.

## Contribution

It uncovers Coulomb-induced giant photocurrent enhancement in a single quantum dot, advancing understanding of charge interactions for energy harvesting applications.

## Key findings

- Photocurrent of X+ is up to 30 times larger than neutral exciton.
- Coulomb repulsion increases hole tunneling rate significantly.
- Hole tunneling barrier change is quantified as 8.05 meV.

## Abstract

Understanding the carrier excitation and transport processes at the single-charge level plays a key role in quantum-dot-based solar cells and photodetectors. Here, we report on Coulomb-induced giant photocurrent enhancement of positive charged trions (\emph{X$^+$}) in a single self-assembled InAs/GaAs quantum dot embedded in an \emph{n-i-}Schottky device by high-resolution photocurrent (PC) spectroscopy. The Coulomb repulsion between the two holes in the \emph{X$^+$} increases the tunneling rate of the hole, and the remaining hole can be reused as the initial state to regenerate \emph{X$^+$} again. This process brings the PC amplitude of \emph{X$^+$} up to 30 times larger than that of the neutral exciton. The analysis of the hole tunneling time gives the equivalent change of hole tunnel barriers caused by Coulomb interaction between two holes with a value of 8.05 meV during the tunneling process. Our work brings a fundamental understanding of energy conversion for solar cells in nanoscale to improve internal quantum efficiency for energy harvesting.