Thermal Transport Properties of Two-Dimensional Materials at Mechanical Strains

Two-dimensional (2D) materials have been extensively studied and exploited in various fields such as electronics, sensors, bioengineering, energy storage, and conversion technology due to their excellent electronic, optical, and thermal properties. Specifically, in recent years, they become emergent thermal and thermoelectric materials with the potential widespread in wearable electronics applications. Due to their potential promising applications, it is of significance to discover the thermal transport properties of 2D materials at large mechanical strains, and thus develop novel wearable electronics with high performance. In this work, we have used a refined version of the opto-thermal Raman technique to study the thermal conductivity of 2D materials, at large mechanical strains. In this technique, a laser is focused at the center of a thin film and used to measure the peak position of a Raman-active mode. Another group of experiments is conducted by placing the samples on a heating platform and monitoring the change of Raman-active mode peak position shift. Combining these two sections of experiments provides us with the thermal modeling that can then be used to extract the thermal conductivity from the measured shift rate. These results are of significance to discovering the thermal transport properties of 2D materials at large mechanical strains and thus develop efficient 2D thermal materials which can sustain the large mechanical strains and in turn use strains to tune their thermal properties.