Efficient liquid exfoliation of KP₁₅ nanowires aided by Hansen's empirical theory

The KP₁₅ nanowires with one-dimensional properties has a defect-free surface, high anisotropy, and carrier mobility which is desirable for the development of novel nanodevices. However, the preparation of nanoscale KP₁₅ is still inefficient. In this work, the Hansen solubility parameters of KP₁₅ were first obtained. Based on the Hansen's empirical theory, the concentration of liquid-exfoliated KP₁₅ nanowires was improved to 0.0458 mg·mL^-1 by a solution containing 50% water and 50% acetone. Approximately 79% of the KP₁₅ nanowires had a thickness value below 50 nm and 60.9% of them had a width value below 100 nm. The thinnest KP₁₅ nanowires reached 5.1 nm and had smooth boundaries. Meanwhile, strong temperature-dependent Raman response in exfoliated KP₁₅ nanowires has been observed, which indicates a strong phonon-phonon coupling in those nanowires. This is helpful for non-invasive temperature measurements of KP₁₅ nanodevices.