Wafer-Scale 2D PtTe2 Layers for High-Efficiency Mechanically Flexible Electro-Thermal Smart Window Applications

2D transition metal dichalcogenide (TMD) layers have gained increasing attention for a variety of emergent electrical, thermal, and optical applications. Recently developed metallic 2D TMD layers have been projected to exhibit unique attributes unattainable in their semiconducting counterparts; e.g., much higher electrical and thermal conductivities coupled with mechanical flexibility. In this work, we explored 2D platinum ditelluride (2D PtTe2) layers – a relatively new class of metallic 2D TMDs – by studying their previously unexplored electro-thermal properties for unconventional window applications. We prepared for wafer-scale 2D PtTe2 layers-coated optically transparent and mechanically flexible willow glasses via a thermally-assisted tellurization of Pt films at a low temperature of 400 oC. The 2D PtTe2 layers-coated windows exhibited thickness-dependent optical transparency and electrical conductivity of > 106 S/m – higher than most of the previously explored 2D TMDs. Upon an application of the electrical bias, these windows displayed a significant increase in temperature driven by Joule heating as confirmed by the infrared (IR) imaging characterization. Such superior electro-thermal conversion efficiencies inherent to 2D PtTe2 layers were utilized to demonstrate various applications, including thermochromic display and electrically-driven defogging windows accompanying mechanical flexibility. Comparisons of these performances confirm the superiority of the wafer-scale 2D PtTe2 layers over other nanomaterials explored for such applications.