Investigating polymorphism in molecular semiconductors and fabricating organic field-effect transistors

  • Crystallization
  • 18 July 2024

About the webinar

The perquisites of organic semiconductors (OSCs) in the vivid field of organic electronics have attracted much attention due to advantages like cost-effectiveness, solution processibility, versatility in material synthesis, and compatibility with a wide range of substrates.

A key property in OSCs is charge carrier mobility, which essentially depends on molecular packing, as even the slightest changes or thermal fluctuations in the packing of OSC can significantly impact the mobility. Organic molecules are constructed by weak interactions like van der Waals, which makes the OSCs prone to adopt multiple packing arrangements, thus giving rise to polymorphism. Therefore, polymorph screening in bulk and thin films and stability assessment of each crystal form are crucial for material development.

In this webinar, guest speaker Priya Pandey from Université Libre de Bruxelles presents a study of polymorphism and crystal growth of [1]benzothieno[3,2-b]benzothiophene (BTBT) derivatives functionalized with different side chains. The important role of peripheral side chains has been studied since they can promote different packing arrangements. The study commenced with solution-mediated recrystallization to screen bulk polymorphs of OSCs, evaluating their stability and transformation kinetics. This was followed by exploring polymorphism in thin films using non-equilibrium methods like thermal gradient and solution shearing to study nucleation, crystal growth, and morphology under controlled conditions. Analysis of crystal phases in bulk and thin films guided the optimization of manufacturing conditions for fabricating organic field-effect transistors (OFETs). Hole mobility values extracted from transfer curves were used to evaluate charge transport properties, supported by calculations of ionization potential and transfer integrals to correlate solid-state structure with electronic behaviour. Additionally, the study explored mechanical properties influenced by packing arrangements and intermolecular interactions, demonstrating the mechanical deformability of OSCs as advantageous for flexible electronic devices, and enhancing durability against fractures.

Guest speaker

Priya Pandey

Postdoctoral Researcher at Université Libre de Bruxelles (ULB)

Priya Pandey earned her bachelor’s degree in chemistry honours from West Bengal State University in 2017, followed by her M.Sc. in Nanotechnology from the Central University of Gujarat in 2019. During her time as a project student at the Indian Institute of Science Education and Research (IISER), Kolkata, she conducted research on the mechanical properties of Active Pharmaceutical Ingredients (APIs). She conducted her Ph.D. research from 2020-2023 at PolyCrystalLine SpA, in Italy under the supervision of Dr. Enrico Modena and co-supervised by Prof. Lucia Maini from the Molecular Crystal Engineering group at the University of Bologna. Her Ph.D. was part of the European ITN network, funded by the European Union’s Horizon 2020 research and innovation programme through the Marie Skłodowska-Curie grant (UHMob). Her Ph.D. work focused on the study and characterization of polymorphs of BTBT derivatives and their application in organic electronics. Following her Ph.D., she embarked on her first postdoctoral appointment at Université libre de Bruxelles in January 2024, where she is exploring polymorphism in APIs (PolyAPI) in Prof. Yves Geerts’ group.

Watch webinar recording