There is currently a growing interest in the possibility of using strong light-matter coupling occurring in cavities to modify transport properties in semiconductors, with potential applications for optoelectronic and photovoltaic devices. While most research has focused on charge and energy transport under "electronic strong coupling", where an electronic transition in the visible frequency range is coupled to a cavity mode, the interaction between charge transport and vibrational strong coupling remains to be fully explored. Vibrational strong coupling occurs when a vibrational (or a phonon) mode in the mid-to-far infrared frequency range is coupled to a cavity mode. In this case, the strength of the light-matter coupling can be comparable to the vibrational mode frequency, a situation refered to as "ultrastrong coupling", where the quantum ground state is profoundly modified. This opens up very interesting prospects, where the "light component" of the ground state could significantly alter charge transport, potentially leading to new physics. I

In the framework of the MSCA doctoral network project "SPARKLE - Scientific training Programme for Advanced Research and Knowledge in Light-matter Engineering", the objective of this PhD project is to investigate theoretically the effects of vibrational strong/ultrastrong coupling on charge transport in doped semiconductors. The theoretical work will be conducted in collaboration with experimentalists to identify potentially relevant materials and designs.