Light-Driven Dynamics in Hybrid Nanostructures: From Ultrafast Photoemission Studies to Functional Optical Systems

Understanding and controlling light-driven electronic processes at the nanometer scale is important for the continued development of next-generation optoelectronic devices, energy-efficient information processing, and emerging neuromorphic systems. This thesis investigates light-matter interactions in nanoscale systems across a broad range of timescales, from femtosecond plasmon dynamics to molecular memory persisting for hours or days.
The first part of this work is focused on fundamental studies of ultrafast electronic processes using time-resolved photoemission electron microscopy (TR-PEEM). Direct visualization of plasmonic near fields in silver nanowires excited by few-cycle short-wavelength infrared (SWIR) pulses reveals strong spatially localized field enhancement and demonstrates the impact of nanoscale geometrical variations on plasmonic behavior. The extension of this concept is further explored in semiconductor-metal nanowire systems, highlighting the role of composition and structure in determining carrier excitation and propagation dynamics. The experimental observations are supported by electromagnetic simulations and an interpretation of photoemission processes.
Beyond these fundamental studies, this work also explores hybrid nanowire-molecule systems aimed at neuromorphic device functionality. For this, donor-acceptor Stenhouse adduct (DASA) dyes are integrated with semiconductor nanowire devices, combining reversible molecular switching with electronic readout. In these hybrid devices, optical writing and electrical reading are largely decoupled, enabling dynamic control of the device response. Furthermore, the concept is extended to wavelength-selective multi-dye systems, demonstrating the possibility of independently addressable optical channels within a single device architecture. The resulting devices exhibit memory, history-dependent behavior, and tunable temporal dynamics that resemble one of the key aspects of
neuromorphic functionality.
By bridging fundamental studies of ultrafast nanoscale processes with the development of functional hybrid devices, this thesis explores how light can be used to probe electronic processes on their natural timescales and how experimental techniques and materials can be combined to advance light-controlled electronics and information processing.