Mono-Elemental Properties of 2D Black Phosphorus Ensure Extended Charge Carrier Lifetimes under Oxidation: Time-Domain Ab Initio Analysis

Abstract

An attractive two-dimensional semiconductor with tunable direct bandgap and high carrier mobility, black phosphorus (BP), is used in batteries, solar cells, photocatalysis, plasmonics, and optoelectronics. BP is sensitive to ambient conditions, with oxygen playing a critical role in structure degradation. Our simulations show that BP oxidation slows down charge recombination. This is unexpected, since typically charges are trapped and lost on defects. First, BP has no ionic character. It interacts with oxygen and water weakly, experiencing little perturbation to electronic structure. Second, phosphorus supports different oxidation states and binds extraneous atoms avoiding deep defect levels. Third, soft BP structure can accommodate foreign species without disrupting periodic geometry. Finally, BP phonon scattering on defects shortens quantum coherence and suppresses recombination. Thus, oxidation can be regarded as production of a self-protective layer that improves BP properties. These BP features should be common to other monoelemental 2D materials, stimulating energy and electronics applications.

Fully Light‐Controlled Memory and Neuromorphic Computation in Layered Black Phosphorus

“…[ 17,61–63,70 ] The phonon scattering on oxidation induced defects shortens the quantum coherence and prolongs the charge recombination. [ 71 ] This results in the observation of a persistent photocurrent in BP underpinned by a slow recovery of photocurrent and leading to the formation of a window that we exploit for memory effect in our devices.…”

Band‐Gap and Charge Transfer Engineering in Red Phosphorus‐Based Composites for Enhanced Visible‐Light‐Driven H2 Evolution

“…The results from the PL spectra and EIS Nyquist plots demonstrate that surface oxygen covalent functionalization of RP can significantly improve the separation and transfer efficiencies of photogenerated carriers, thus enhancing the photocatalytic performance. The possible explanation for the suppressed electron–hole recombination by oxygen‐containing functional groups is that the oxygen impurities in RP can scatter the higher frequency phonons to generate softer phonons with lower frequency, further decreasing the nonadiabatic coupling and shortening quantum coherence time, which are regarded as beneficial for electron–hole separation …”

Tailoring exciton dynamics of monolayer transition metal dichalcogenides by interfacial electron-phonon coupling

“…In addition, the excited carrier can hop from one KS orbital to another, in which the hopping probability is determined by the non-adiabatic coupling (NAC) elements between different KS orbitals (see Supplementary Note 4). Such method has been successfully applied to describe the nonradiative e-h recombination dynamics in 2D materials 20,48 . As shown in Fig.…”