Candidate: Zhiqiao Yang
Date: Sept. 11, 2023
Time: 1:30 PM - 2:30 PM
Location: Remote attendance
Supervisor(s): Na Young Kim, Irene Goldthorpe
Abstract
Two-dimensional materials have garnered significant attention in the research community due to their unique physical and electrical properties. Among these materials, molybdenum disulfide (MoS2) is a promising candidate for the development of next-generation electronic and optoelectronic devices, which is attributed to its layer-dependent bandgap, a strong light-matter interaction despite its atomically thin nature and potentially high in-plane carrier mobility. Mayer rod coating emerges as a scalable solution processing method to directly deposit dispersions of MoS2 flakes on a variety of substrates, thus paving the way for the fabrication of flexible electronics in the future. In this study, to the best of the author’s knowledge, rod coating was employed first time to deposit a MoS2 dispersion in ethanol onto SiO2/Si substrates. The optimal MoS2 film estimated several hundreds of nanometers thick on a SiO2/Si substrate pretreated with piranha solution and oxygen plasma using a 100 mg/ml MoS2 solution for 16 coats was thermally annealed at 400 °C in argon to achieve a sheet resistance on the order of kiloohms per square (KΩ/□). Thin film transistors (TFTs) were subsequently fabricated based on the rod-coated MoS2 film, and electrical characterizations demonstrated s-shaped non-linear Isd -Vsd characteristics but no significant gate modulation effect was observed. Rod coating was also applied to deposit silver nanowires on a glass substrate, showcasing the versatility of the method. The silver nanowire electrode was integrated into light emitting devices (LEDs) based on tungsten disulfide (WS2), enabling bidirectional emission as transparent LEDs. This study indicated rod coating as a viable method for the deposition of 2D and other low-dimensional materials, providing an alternative approach for the assembly of 2D materials other than commonly reported solution processing methods in the literature.