Recent Progress on Stability and Passivation of Black Phosphorus

Abstract

From a fundamental science perspective, black phosphorus (BP) is a canonical example of a material that possesses fascinating surface and electronic properties. It has extraordinary in-plane anisotropic electrical, optical, and vibrational states, as well as a tunable band gap. However, instability of the surface due to chemical degradation in ambient conditions remains a major impediment to its prospective applications. Early studies were limited by the degradation of black phosphorous surfaces in air. Recently, several robust strategies have been developed to mitigate these issues, and these novel developments can potentially allow researchers to exploit the extraordinary properties of this material and devices made out of it. Here, the fundamental chemistry of BP degradation and the tremendous progress made to address this issue are extensively reviewed. Device performances of encapsulated BP are also compared with nonencapsulated BP. In addition, BP possesses sensitive anisotropic photophysical surface properties such as excitons, surface plasmons/phonons, and topologically protected and Dirac semi-metallic surface states. Ambient degradation as well as any passivation method used to protect the surface could affect the intrinsic surface properties of BP. These properties and the extent of their modifications by both the degradation and passivation are reviewed.

High Electron Mobility of Amorphous Red Phosphorus Thin Films

“…It has been shown that all the allotropic forms of phosphorus,i ncluding the crystalline ones,c an react with O 2 and H 2 Oi nt he air to form phosphorus oxides,p hosphoric acid or phosphine gas. [53,54] RP also reacts with I 2 at moderate temperature. [53] Materials that only work under controlled conditions have limited applications.T op revent these reactions,various methods have been used to improve the stability of materials in air.F or instance,J eong et al [55] have used thermal etching to generate an oxide layer on BP,w hich stabilizes the material.…”

“…[53,54] RP also reacts with I 2 at moderate temperature. [53] Materials that only work under controlled conditions have limited applications.T op revent these reactions,various methods have been used to improve the stability of materials in air.F or instance,J eong et al [55] have used thermal etching to generate an oxide layer on BP,w hich stabilizes the material. Such approach was not successful when applied to our a-RP films as moisture was absorbed by the films,g enerating phosphoric acid (See Figure S6).…”

“…[53,54] RP also reacts with I 2 at moderate temperature. [53,54] RP also reacts with I 2 at moderate temperature.…”

Emerging Applications of Elemental 2D Materials

“…Of the group V elements, air stability remains a common issue. Phosphorene, the puckered or “black” phase, for instance, has been extensively investigated but remains highly susceptible to oxidation in air, making encapsulation schemes necessary . Meanwhile, antimonene crystals with buckled structure have been shown to be stable in air and chemically robust .…”

“…Phosphorene, the puckered or "black" phase, for instance, has been extensively investigated but remains highly susceptible to oxidation in air, making encapsulation schemes necessary. [47][48][49] Meanwhile, antimonene crystals with buckled structure have been shown to be stable in air and chemically robust. [50] In addition, crystal forms of antimonene have been predicted to have different degrees of anisotropy in mechanical properties.…”