Light absorbed by a semiconductor is stored as electronic excitations in the form of bound electron-hole pairs, also known as excitons. There is a rich variety of semiconductor nanostructures available today for the design of novel material systems and interfaces with tailor-made functionalities. In particular, atomically thin two-dimensional materials such as graphene and transition metal dichalcogenide (TMDC) monolayers exhibit extraordinary optical and electrical properties. For such materials, with thicknesses below 1 nanometer, I will show that the external dielectric environment strongly influences their electronic states and corresponding disorder [1,2], energy transfer processes , and excited-state dynamics . I will also briefly discuss new experimental approaches to the study of these phenomena and the associated ultrafast dynamics. In addition to the intrinsic scientific interest in understanding materials in this distinctive regime, such control offers a non-invasive approach to engineer material properties and dynamics by tuning the local environment rather than the material itself, yielding a new paradigm for nanoscale devices and energy conversion processes.
Speaker: Archana Raja, UC Berkeley
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