2D Materials and Heterostructures for Addressing Critical Societal Problems

The demand of electric vehicles (EVs) is rapidly growing in the automotive industry due to its high energy efficiency, less emission of CO2 gases and other air pollutants. Many countries are promoting the use of electric vehicles for a better environmental system that is less dependent on fossil fuels and for enhanced mobility around the society. Despite the widespread use of electric vehicles nowadays, there are still many limitations such as a limited driving distance, a long charging time, and a relatively high cost. Therefore, among many other societal problems that the nation faces, this doctoral dissertation study aims to take the EV as the model system that our novel engineering approaches can contribute to make more viable and reliable. In this work, we focused on two critical challenges of electric vehicles: a relatively short driving range (or a relatively long charging time) and a nation-wide semiconductor chip (sensor) shortage. We show that both challenges can be well addressed by taking advantage of unique functionalities of 2D materials and heterostructures. Firstly, we have developed a novel wireless charging system prototype for EV by using LEDs which are powered by piezoelectric 2D nanomaterials (MoS2) as the energy transmitter source and thin film solar panels placed at the bottom of the vehicle as the receiver. This will ultimately deliver the harvested energy to the vehicle's battery. Next, we have investigated the potential of 2D materials to become the high-sensitivity temperature sensing platform for use in EVs. This is very critical because temperature sensors need to protect various semiconductor parts, electronics, and the battery system from overheating. EVs specifically require high-performance temperature sensors of a smaller size, lighter weight and higher energy-efficiency while operating at a wider temperature range. Meeting these requirements using conventional temperature sensors is challenging due to a complicated fabrication or signal processing process required. Here, we have studied the temperature-dependent spectroscopic and electrical characteristics of MoS2, MoS2-PtSe2, and MoS2-PtTe2 for the purpose of exploring them as the next-generation temperature sensor, finding that the MoS2-PtTe2 heterostructure exhibits the enhanced temperature sensitivity.