Platinum diselenide PtSe₂: An ambient-stable material for flexible electronics

Recent progress in the fabrication techniques and growth process of Transition-metal dichalcogenides (TMDs) such as PtSe₂ has led to their application in a variety of fields ranging from flexible electronics to wearable optoelectronics, sensors, and energy storage. TMDs such as PtSe2 can be highly deformed without mechanical damage, have excellent electrical conductivity, and behave like a semiconductor when reduced to a single atomic layer thickness. Although considerable research has been devoted to theoretically understand the behavior of single layer PtSe2, there is a lack of information on the experimental characterization of the ambient stability and mechanical properties of bulk PtSe₂. Therefore, in this study, the ambient stability and mechanical properties of single-crystal bulk PtSe2 are assessed using X-ray photoelectron spectroscopy and depth-sensing nanoindentation respectively. The average Young's modulus and hardness values of PtSe₂ are measured as 17.5 and 1.03 GPa respectively using nanoindentation testing. Furthermore, the experimentally calculated Young's modulus is compared to DFT numerical simulations. The ductility of the material is highlighted using the strain hardening exponent (calculated value of 0.07) obtained from analyzing images of material pile-up at high indentation loads. The fracture toughness of PtSe₂ is measured as 2.6MPam using nanoscratch experiments and the calculated value is found comparable to commonly used flexible electronics materials. Finally, ambient stability and flexibility tests underline the long-term and electrical stability of PtSe2 respectively. The characteristics of PtSe2 measured and showcased in this study will pave the way for deploying PtSe₂ in various applications like nanoelectronics, opto-electronics, and photonics.