Periodic Reporting for period 1 - UHMob (Ultra-high Charge Carrier Mobility to Elucidate Transport Mechanisms in MolecularSemiconductors)
Reporting period: 2019-05-01 to 2021-04-30
For a selected set of organic semiconductors, the study of the bulk and surface polymorphism has been completed allowing also the isolation of several single crystals. Crystalline structure determination has been achieved by single crystal and powder diffraction measurements. The thermodynamic and kinetic stability of different polymorphs have been studied both for bulk material than for thin films. Deposition and characterisation with different techniques have been also considered to evaluate the quality and properties of the obtained crystal forms.
With state-of-the-art spectroscopic methods like time-resolved sum frequency generation and optical pump THz probe spectroscopy, dynamics on picosecond timescales of charge-transport in materials varying from polymers to aqueous solution has been studied. It could be concluded that in polymer films electron-phonon scattering plays an important role.
We have to date investigated and optimised OFET devices with several novel molecular semiconductors developed in the programme. Good device performance with high field-effect mobility and low contact resistance has been achieved for DN4T deposited by vacuum sublimation onto heated substrates. We have also developed novel deposition techniques, such as bar-assisted solution shearing, that allow the controlled deposition of blends of molecular semiconductors and insulating binder polymers from solution. Optimisation of deposition conditions has allowed the fabrication of high performance OFETs, which are now available for in-depth transport studies.
Significant progress has been made on achieving the technical conditions needed to study charge carrier mobility under strong coupling to the vacuum field from the mid-infrared to the THz region. In this process, it was serendipitously found that the supramolecular assembly could be significantly modified by coupling simultaneously the solute and solvent vibrations, turning gels into flakes. This provides insight into the fundamental changes induced by such coupling and will help other aspects of the project research.
Fifteen talented young researchers have been hired. An individual Personal Career Development Plan (PCDP) has been established for each of them. They are continuously being trained in different interdisciplinary technical issues related to scientific objectives of the project as well as in a large variety of soft skills. The young researchers are collaborating together intensively and are presenting their results in meetings.
Each partner has been actively involved in advertising open positions to recruit the young researchers, promoting the project, and participating to online events. In parallel, all ESRs have been actively committed in disseminating through papers and online events.
Project media channel has been regularly updated with the ESRs social media campaign via the Twitter https://twitter.com/UHMob_MSCA and LinkedIn https://www.linkedin.com/in/uhmob-european-training-network-465673189/ accounts.