Ultrahigh thermal isolation across heterogeneously layered two-dimensional materials

TLDR

Heterogeneous integration of nanomaterials has enabled advanced electronics and photonics, but thermal applications lag due to the shorter wavelengths of phonons compared to electrons and photons. The study demonstrates unusually high thermal isolation across ultrathin heterostructures by layering atomically thin two‑dimensional materials. Raman thermometry is used to measure interlayer thermal resistance, revealing that ultrahigh isolation arises from mass‑density and phonon‑density‑of‑states mismatches between the 2D layers. Artificial stacks of monolayer graphene, MoS₂, and WSe₂ exhibit thermal resistance over 100 times that of thicker SiO₂ and effective conductivity below air, offering ultrathin thermal insulation for phononics, energy harvesting, and heat routing in compact devices.

Abstract

Heterogeneous integration of nanomaterials has enabled advanced electronics and photonics applications. However, similar progress has been challenging for thermal applications, in part due to shorter wavelengths of heat carriers (phonons) compared to electrons and photons. Here, we demonstrate unusually high thermal isolation across ultrathin heterostructures, achieved by layering atomically thin two-dimensional (2D) materials. We realize artificial stacks of monolayer graphene, MoS2, and WSe2 with thermal resistance greater than 100 times thicker SiO2 and effective thermal conductivity lower than air at room temperature. Using Raman thermometry, we simultaneously identify the thermal resistance between any 2D monolayers in the stack. Ultrahigh thermal isolation is achieved through the mismatch in mass density and phonon density of states between the 2D layers. These thermal metamaterials are an example in the emerging field of phononics and could find applications where ultrathin thermal insulation is desired, in thermal energy harvesting, or for routing heat in ultracompact geometries.