High performance electronic devices based on two dimensional nano-scale metal oxides and chalcogenides

Over the past few decades, two dimensional (2D) materials have received significant attention and experienced considerable improvement. Layered and nonlayered metal chalcogenides (MCs) and metal oxides (MOs) among the wide range of 2D nanomaterials are most favorable owing to their unique electronic and optoelectronic properties. However, despite many significant developments, the synthesis of large-area, ultrathin 2D materials remains a great technological challenge, limiting their commercial appeal. Therefore, this PhD research explores the synthesis and fundamental properties of large-area 2D MCs and MOs and investigates their viabilities in applications such as chemical sensing and electronics. Overall, this thesis consists of three key studies. In the first part of this PhD, layered tin monosulfide (SnS) is exfoliated into 2D nanosheets using a liquid-phase exfoliation technique. Excitation wavelength-dependent photoluminescence (PL) is found, and the excitonic radiative lifetime is more than one order enhanced compared to that of bulk counterpart due to the quantum confinement effect. Physisorption of NO2 results in the formation of dipoles on the surface of 2D SnS, causing the re-distribution of photoexcited charges in the body and therefore modifying PL properties. The synthesized 2D nanosheet is found to exhibit excellent sensitivity and selectivity towards NO2 gas molecules under light irradiation at a relatively low operating temperature.