Abstract
Visible photonics in low-dimensional systems has attracted intensive attention from industry and academic communities since it has benefited human beings’ life from the past century. Extensive of research has been conducted from structure engineering to material science on the generation of visible lights, including structural colors and visible emissions. Because optical devices are indispensable medium to visually convey information in current society, it is significant to develop tunable structural colors and highly scalable optical devices with efficient visible emissions. Recently, with the development of nanotechnologies, structural color generation has progressed rapidly. High-resolution structural colors using different metals and geometries have been widely studied with a broad range of applications, such as reflective display, securities, data storage and optical sensors. However, despite the success, a fundamental drawback remains: it is challenging to alter the features of the physical structures and optical performances of low-dimensional solid-sate optoelectronic devices once fabricated. To overcome this challenge, this thesis proposes an unprecedented paradigm that the inner layers of a solid-state thin film structures can be floated and modified, leading to dynamic structure alternation with zero standby power. This enables reorganization and restoration of solid-state structures at the nanoscale in a single XI device, opening a new route to construct active semiconductor devices with artificial nanostructures. In addition, the integration of ultra-thin emitters with solid-sate structural colors will provide scalable and multifunctional optoelectronics for more applications in different environment. Two-dimensional (2D) transition-metal dichalcogenides (TMDs) have attracted intensive interest due to the direct-band gap transition in the monolayer form, positioning them as the potential next generation optoelectronic/photonic devices. However, till date, the active optical properties of TMDs are constrained to a specific excitation energy range. For example, the most effective excitation energy for WS2 monolayers lie in green-yellow spectral region. This limits the ability to locally control and manipulate the photo luminescent performance of WS2 for multifunctional applications. In this work, we demonstrate a new energy transfer method to modulate optical properties of TMDs under a larger excitation range spanning from UV to visible light. The emission energy from Ln3+ sources can be effectively transferred to the TMD monolayers under low power exposure (0.13 mW, 10 s) at room temperature, activating the characteristic monolayer fluorescence in place of Ln3+ emission signatures. The novel Ln /TMDs photonics can potentially tune the excitation of TMDs to provide variable yet controllable emissions under influence of the surrounding. XII In this thesis, the first tunable solid-state thin-film optoelectronic framework is designed and demonstrated under a voltage bias, which can build blocks for potential reflective and energy-efficient color technologies. This scalable solid-state low-dimensional optoelectronic device can benefit electronics, such as the memristors, since this work firstly shows memristors’ optical properties and thus, the studies present an intriguing result. Besides, for the emit light using a backlit light source, Ln/TMDs hybrids have been prepared to overcome the emission limitations of TMDs monolayers due to the band nesting phenomenon. This method enhanced the emission efficiency of WS2 monolayers around 10 times under UV excitation, and expand the excitation range from visible lights to UV. This thesis will describe the two optical tuning approaches on the low-dimensional systems form structures and materials, used in reflective and light emissions fields.