# Charging energy spectrum of black phosphorus quantum dots

## TL;DR

This theoretical study investigates the charging behavior and energy spectrum of black phosphorus quantum dots, revealing size and layer-dependent maximum electron capacity and associated structural stability limits.

## Contribution

The paper provides the first detailed analysis of charging effects and energy spectra in black phosphorus quantum dots with different sizes and layers, highlighting stability thresholds.

## Key findings

- Single layer 3 nm BPQDs can hold up to 16 electrons.
- Average additional energy ($E_A$) ranges from 0.2 to 0.4 eV depending on size and layers.
- Structural instability occurs beyond maximum electron capacity.

## Abstract

We present a theoretical study of the charging effects in single and double layer black phosphorus quantum dots (BPQDs) with lateral sizes of 2 nm and 3 nm. We demonstrate that the charging of BPQDs are able to store up to an $N_{max}$ electron (that depends on the lateral size and number of layers in the QD), after which structural instabilities arises. For example, 3 nm wide hydrogen-passivated single layer BPQDs can hold a maximum of 16 electrons, and an additional electron causes the expelling of hydrogen atoms from the QD borders. We also calculated the additional energy ($E_A$) spectrum. For single layer QDs with 2 and 3 nm of lateral sizes, the average $E_A$ is around 0.4 eV and 0.3 eV, respectively. For double layer QDs with the same sizes, the average $E_A$ is around 0.25 eV and 0.2 eV, respectively.