Stable aqueous dispersions of optically and electronically active phosphorene.
Understanding and exploiting the remarkable optical and electronic properties of phosphorene require mass production methods that avoid chemical degradation. Although solution-based strategies have been developed for scalable exfoliation of black phosphorus, these techniques have thus far used anhydrous organic solvents in an effort to minimize exposure to known oxidants, but at the cost of limited exfoliation yield and flake size distribution. Here, we present an alternative phosphorene production method based on surfactant-assisted exfoliation and postprocessing of black phosphorus in deoxygenated water. From comprehensive microscopic and spectroscopic analysis, this approach is shown to yield phosphorene dispersions that are stable, highly concentrated, and comparable to micromechanically exfoliated phosphorene in structure and chemistry. Due to the high exfoliation efficiency of this process, the resulting phosphorene flakes are thinner than anhydrous organic solvent dispersions, thus allowing the observation of layer-dependent photoluminescence down to the monolayer limit. Furthermore, to demonstrate preservation of electronic properties following solution processing, the aqueous-exfoliated phosphorene flakes are used in field-effect transistors with high drive currents and current modulation ratios. Overall, this method enables the isolation and mass production of few-layer phosphorene, which will accelerate ongoing efforts to realize a diverse range of phosphorene-based applications.
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208.
Joohoon
J
Kang
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208.
Spencer A
SA
Wells
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208.
Joshua D
JD
Wood
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208.
Jae-Hyeok
JH
Lee
Graduate Program in Applied Physics, Northwestern University, Evanston, IL 60208.
Xiaolong
X
Liu
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208.
Christopher R
CR
Ryder
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208.
Jian
J
Zhu
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439.
Jeffrey R
JR
Guest
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439.
Chad A
CA
Husko
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208; Graduate Program in Applied Physics, Northwestern University, Evanston, IL 60208; Department of Chemistry, Northwestern University, Evanston, IL 60208; Department of Medicine, Northwestern University, Evanston, IL 60208; Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208 m-hersam@northwestern.edu.
Mark C
MC
Hersam
black phosphorus; deoxygenated water; field-effect transistor; liquid phase exfoliation; photoluminescence