Electrochemical Delamination of Ultralarge Few-Layer Black Phosphorus with a Hydrogen-Free Intercalation Mechanism

Due to strong interlayer interaction and ease of oxidation issues of black phosphorus (BP), the domain size of artificial synthesized few-layer black phosphorus (FL-BP) crystals is often below 10 mu m, which extremely limits its further applications in large-area thin-film devices and integrated circuits. Herein, a hydrogen-free electrochemical delamination strategy through weak Lewis acid intercalation enabled exfoliation is developed to produce ultralarge FL-BP single-crystalline domains with high quality. The interaction between the weak Lewis acid tetra-n-butylammonium acetate (CH(3)COOTBA) and P atoms promotes the average domain size of FL-BP crystal up to 77.6 +/- 15.0 mu m and the largest domain size is found to be as large as 119 mu m. The presence of H+ and H2O is found to sharply decrease the size of as-exfoliated FL-BP flakes. The electronic transport measurements show that the delaminated FL-BP crystals exhibit a high hole mobility of 76 cm(2) V-1 s(-1) and an on/off ratio of 10(3) at 298 K. A broadband photoresponse from 532 to 1850 nm with ultrahigh responsivity is achieved. This work provides a scalable, simple, and low-cost approach for large-area BP films that meet industrial requirements for nanodevices applications.

Automated summary

An electrochemical delamination strategy using weak Lewis acid intercalation has been developed to produce ultralarge FL-BP single-crystalline domains, significantly increasing the average domain size of crystals and demonstrating high hole mobility and broad photoresponse capability.