Multifunctional Optoelectronics via Harnessing Defects in Layered Black Phosphorus

Abstract

Layered black phosphorus (BP), a promising 2D material, tends to oxidize under ambient conditions. While such defective BP is typically considered undesirable, defect engineering has in fact been exploited in contemporary materials to create new behaviors and functionalities. In this spirit, new opportunities arising from intrinsic defect states in BP, particularly through harnessing unique photoresponse characteristics, and demonstrating three distinct optoelectronic applications are demonstrated. First, the ability to distinguish between UV-A and UV-B radiations using a single material that has tremendous implications for skin health management is shown. Second, the same device is utilized to show an optically stimulated mimicry of synaptic behavior opening new possibilities in neuromorphic computing. Third, it is shown that serially connected devices can be used to perform digital logic operations using light. The underpinning photoresponse is further translated on flexible substrates, highlighting the viability of the technology for mechanically conformable and wearable systems. This demonstration paves the way toward utilizing the unexplored potential offered by defect engineering of 2D materials for applications spanning across a broad range of disciplines.

Artificial Synapse Based on Black Phosphorus/SnS 2 Heterostructure Transistor for Neuromorphic Computing with High Accuracy

“…Importantly, three dispersion-less impurity states emerge around 0.480 eV in the band structure of the oxidized BP layer, similar to the defect-induced states observed in oxidized BP multilayers. These impurity states are proposed to be the physical origin of the nonlinear transport behavior observed in BP FETs, consistent with our experimental findings shown in Figure b. While the oxidized SnS 2 maintains a comparable bandgap (2.184 eV), its band morphology and energy levels exhibit only slight changes after oxidation.…”

Super-Slippery Degraded Black Phosphorus/Silicon Dioxide Interface

“…However, no oxide species were observed in the BP layers until the interface area. The Si 2p, P 2p, and O 1s peaks coexisted at the interface with the O 1s peak exhibiting as the strongest one, indicating the enhanced O content at the interface, being consistent with the observed phosphorus oxide at both the top and bottom interfaces of the BP device . In addition, the XPS depth profiles of the BP/Si system before and after degradation were obtained for comparison (Supporting Information, Figure S10), revealing that the inducement of O 1s peak at the BP/Si interface was directly related with the degradation of the BP flake.…”

Broad-Spectrum Solvent-free Layered Black Phosphorus as a Rapid Action Antimicrobial

“…Oxygen is known to adsorb on the BP surface, which can oxidize further on exposure to ambient conditions. 36,37 A high-resolution transmission electron microscopy (HR-TEM) (Figure 1D) was taken from deposited BP, and the inset shows that the lattice spacing was found to be 0.26 nm, which is consistent with the spacing between two sheets of phosphorus. 38 A typical scanning electron microscopy (SEM) micrograph of the material is shown in Figures S1B and S4.…”