Atomic and organic semiconductors interfaces with inorganic semiconductors are promising materials for use in next-generation electronic and optoelectronic devices. A predictive-level understanding of the interfaces is lacking which hinders rational design of such devices. This is attributed to the key processes, e.g. charge generation, separation, delocalization and extraction, which are heavily interfacial in nature and difficult to simulate. Thus, it is imperative to understand the fundamental processes at individual interfaces to enable design and optimization of next-generation technologies. This work aims to understand these interfaces by studying the interfacial processes using optical photoemission spectroscopy techniques.
In this dissertation, I focus on alkali metal and molecular interfaces with layered materials to understand and control the dynamics and electronic and optical properties of the interface. Initially, I aim to characterize the nature of layered materials (SnS2 and MoS2) that exhibit unusual thickness-dependent properties, which already affords tunable materials properties. I demonstrate the anisotropy of the many-layered crystal at ultrafast timescales not yet realized. Pairing the layered material with thin films (K, CuPc and PTCDA) demonstrates layer decoupling and quantum confinement effects that show an enhancement of carrier delocalization at the interface. Furthermore, studies show a systematic tuning of the dielectric environment of the layered material dependent upon adsorbate thin film thickness. Overall, this work elucidates key interfacial interactions of select atoms and molecules on layered materials that can be used to understand this class of materials and their implementation in nanodevices
