Metal‐Ion‐Modified Black Phosphorus with Enhanced Stability and Transistor Performance

Black phosphorus (BP), a burgeoning elemental 2D semiconductor, has aroused increasing scientific and technological interest, especially as a channel material in field‐effect transistors (FETs). However, the intrinsic instability of BP causes practical concern and the transistor performance must also be improved. Here, the use of metal‐ion modification to enhance both the stability and transistor performance of BP sheets is described. Ag+ spontaneously adsorbed on the BP surface via cation–π interactions passivates the lone‐pair electrons of P thereby rendering BP more stable in air. Consequently, the Ag+‐modified BP FET shows greatly enhanced hole mobility from 796 to 1666 cm2 V−1 s−1 and ON/OFF ratio from 5.9 × 104 to 2.6 × 106. The mechanisms pertaining to the enhanced stability and transistor performance are discussed and the strategy can be extended to other metal ions such as Fe3+, Mg2+, and Hg2+. Such stable and high‐performance BP transistors are crucial to electronic and optoelectronic devices. The stability and semiconducting properties of BP sheets can be enhanced tremendously by this novel strategy. A simple and effective metal‐ion modification strategy based on cation–π interactions is applied to black phosphorus to enhance both its air stability and its transistor performance. Such stable and high‐performance black‐phosphorus transistors, which are enhanced tremendously by this novel strategy, have large potential in electronic and optoelectronic devices.