Optical properties of black phosphorus

Optical and Optoelectronic Properties of Black Phosphorus and Recent Photonic and Optoelectronic Applications

“…The strong anisotropic optical absorption for the lowest energy transition originates from the symmetry selection forbidden rule . The BP crystal possesses an inversion symmetry and mirror reflection symmetry exclusively along the x ‐axis, so that the optical transition for electron states located at the Γ point must obey the polarization‐conservation rule.…”

“…When the excitation power is sufficiently high, 2D BP shows saturable optical absorption due to the Pauli blocking. That is, when the photoinduced carriers occupy the empty states in the conduction and valence bands, further interband transitions are forbidden, leading to reduced optical absorption just above the bandgap energy with increasing incident power . The intensity‐dependent optical transmission is a key factor in the saturable absorber (SA), which is an important nonlinear optical device to convert continuous laser output to a train of laser pulses .…”

“…To address this issue, 2D nanomaterials come into researchers' sight and have garnered tremendous research attention . Heralded by the discovery of graphene, many types of 2D materials have sprung up, including hexagonal boron nitride ( h BN), transition metal dichalcogenides (TMDs), III–VI compounds, and black phosphorus (BP) . These materials have similar layered structure to graphite so that they can be isolated down to single or several atomic layers.…”

Two‐Dimensional Materials for Antimicrobial Applications: Graphene Materials and Beyond

“…Here, we highlight the merits of BP nanosheets for bactericidal uses. First, BP nanosheets have a layer‐number‐dependent bandgap of between 0.3 and 2 eV, the tuning range of which is larger than any other 2D material . This adjustable bandgap enables the broad absorption of BP nanosheets from the visible to the mid‐infrared region, and endows them with photothermal and photodynamic properties in the NIR region .…”

“…First, BP nanosheetsh ave al ayer-number-dependentb andgap of between 0.3 and 2eV, [228] the tuning range of which is larger than any other 2D material. [229] This adjustable bandgap enablest he broad absorption of BP nanosheets from the visible to the mid-infrared region, and endowst hem with photothermala nd photodynamic properties in the NIRr egion. [230,231] Furthermore, BP can be oxidized to phosphates under ambient conditions that contain oxygen and moisture.…”