Onset of exciton-exciton annihilation in single layer black phosphorus

TL;DR

This study investigates how exciton-exciton annihilation affects exciton dynamics in monolayer black phosphorus, revealing a density-dependent transition that limits quantum yield and impacts optoelectronic device performance.

Contribution

It provides the first detailed analysis of exciton-exciton annihilation onset in monolayer black phosphorus across a wide density range.

Findings

Exciton-exciton annihilation dominates at high exciton densities.

A maximum injection density limits quantum yield.

Non-exponential decay appears with increasing exciton density.

Abstract

The exciton dynamics in monolayer black phosphorus is investigated over a very wide range of photoexcited exciton densities using time resolved photoluminescence. At low excitation densities, the exciton dynamics is successfully described in terms of a double exponential decay. With increasing exciton population, a fast, non-exponential component develops as exciton-exciton annihilation takes over as the dominant recombination mechanism under high excitation conditions. Our results identify an upper limit for the injection density, after which exciton-exciton annihilation reduces the quantum yield, which will significantly impact the performance of light emitting devices based on single layer black phosphorus.