Development of a Novel Charge Accumulation THz Spectroscopy System Operating in an Inert Atmosphere

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Understanding charge transport in organic semiconductors (OS) is not trivial as this process is governed by electronphonon coupling, which refers to the interaction strength between electrons and phonons (i.e. collective molecular vibrations). Unlike in crystalline silicon, the weak non-covalent nature of the intermolecular interactions in OS does not allow to describe electrons and holes in terms of delocalized Bloch waves. Further, a clear picture of the so-called band-like transport is currently missing, partially because electron-phonon interactions are very hard to probe experimentally. However, while techniques such as Raman spectroscopy or neutron scattering could provide a detailed mapping of the phonon/vibrational modes, they fail in probing the interactions of free charges with the phonon modes. ******To fill this major gap, we request the purchase of a customized equipment, a fiber-coupled THz system to be combined with a glovebox, that will allow to pioneer a novel type of spectroscopy, Charge Accumulation THz spectroscopy (CATS), which for the first time will measure in situ electron-phonon interactions in molecular materials. Several research groups at INRS-EMT and in the Montreal area have expressed their interest in exploiting this tool to perform the suggested research. Such novel spectroscopic technique (CATS) promises to represent a major advance in Materials Science and Synthetic Chemistry, as it could give a clear indication of which (molecular) materials are best suited for applications in electronics.***By correlating the collected spectral features in absence and in presence of charges, we could make an efficient screening of the suitability of a given organic molecular design (in the case of OS) for electronics. In the short term, CATS could be extended to other materials such as organic-halide perovskites or quantum dots, which have strong phononic response in the THz range. In the long term, the generated knowledge could support future adoption of CATS as a routine screening tool of materials for electronics.******The strong track records and complementary expertise of the applicants will ensure the productive management and overall success of the proposed research. Furthermore, given the multi-purpose and versatile nature of the requested toolkit, its use will allow to train HQP in at least 7 other research teams, which would make a total of ca. 50 Ph.D. students, 20 post-doctoral fellows (PDFs), 20 M.Sc. students, and will be also available to summer students. Since CATS is a novel and powerful technique that will be developed at INRS-EMT, it has a huge potential to provide marketable skills for all HQP trained on the equipment. The requested equipment will also open up opportunities for broad collaborations with industries and universities and thus enhance the students' training by exposing them to industrial working environments and allowing them to interact with key players in Canada and elsewhere.**