Covalent Functionalization of Few-Layer Black Phosphorus Using Iodonium Salts and Comparison to Diazonium Modified Black Phosphorus

Since the isolation of two-dimensional (2D) phosphorene, black phosphorus (BP) has gained popularity due to its high carrier mobility and tunable bandgap. Poor ambient stability of BP remains a key issue and impedes its use in electronic applications. Here we report a new stabilization strategy based on covalent functionalization of liquid exfoliated few-layer BP using aryl iodonium salts. Arylation of BP using iodonium salts enables covalent modification without inducing oxidation and alters the degradation chemistry of BP by inhibiting bridged oxygen formation through attachment to surface oxygen sites. In comparison, functionalization using aryl diazonium salts results in oxidation and aryl multilayer formation and does not adequately disrupt noncovalent solvent passivation. Aryl functionalization of BP using iodonium salts displays superior ambient stability compared to arylation using diazonium salts associated with greater covalent functionalization as characterized using X-ray photoelectron spectroscopy, scanning transmission electron microscopy, photoluminescence, and attenuated total reflectance infrared spectroscopy.