Meet the Jury lectures by Martin Heeney and Sophia Hayes

9h-10h
Design of low synthetic complexity materials for organic electronic applications

By Prof. Martin Heeney

Abstract

The development of organic semiconductors has rapidly progress in recent years, but often active materials now require highly complex, multi-step synthesis, potentially limiting their large-scale implementation. In this talk I will discuss approaches to prepare materials in just two or three steps, allowing the preparation of conjugated polymers of low synthetic complexity which can be readily upscaled. I will highlight how this approach can be used to readily build libraries of conjugated polymers to rapidly identify promising materials for application in photovoltaic (OPV) and organic electrochemical transistor (OECT) devices. I will also discuss approaches to introduce additional functionality via post-polymerisation backbone modification of electron deficient conjugated polymers. The use of such techniques allows for the incorporation of sensitive functionalities, useful for crosslinking and photopatterning, as well as ionic groups, for application in OECTs and device interlayers. Finally, the synthesis of graft polymers and their application and emissive nanoparticles will be discussed.

About the speaker

Martin Heeney is a Professor of Chemical Science at King Abdullah University of Science and Technology (KAUST) and Professor of Organic Materials at Imperial College. He is a graduate of the University of East Anglia and received his PhD from the same institution in 1999. Following a postdoctoral position with a start-up company in the area of photodynamic therapy, he joined Merck Chemicals in 2000, eventually becoming project leader for the organic electronics team. He made the move to academia in 2007, joining the Materials Department at Queen Mary University of London as a senior lecturer. In 2009 he moved across London to join the Chemistry Department at Imperial College London. He joined KAUST in 2022. His research interests include the design, synthesis and characterisation of conjugated materials for a variety of applications. He has published over 400 research papers, 5 book chapters and over 100 patents. His work has been cited over 34,000 times and he has an h-index of 97. He has been named five times by Thomson Reuters as a HighlyCited researcher in the field of Materials Science, is a recipient of the RSC Corday-Morgan (2013) medal, the RSC Peter Day (2020) award and the Macro group UK medal (2020).

10h-11h
Disentangling the excited state dynamics of conjugated polyelectrolytes self-assembled with ss-DNA with direct molecular probes

By Assoc. Prof. Sophia Hayes

Abstract

In this talk I will present our research activities using a vibrational probe to understand the effect of structure and interactions between molecules on the photophysical behavior of various organic semiconductors. Resonance Raman spectroscopy can provide ground state information on the conformation of conjugated polymers under various environmental conditions or chemical modifications. However, the intensity of the Raman bands in a resonant experiment contains rich information that has been underexplored in organic electronics. I will show how we employ the tools provided by this spectroscopic method to understand the sequence-dependent templating effect of single-stranded DNAs (ssDNAs) on the conformation of conjugated polyelectrolytes and consequently on the photophysical properties and excited state dynamics of a class of cationic polythiophenes (CPT). Combining the selectivity provided by resonance Raman for a particular chromophore we were able to understand the interactions between a CPT and different ssDNAs that lead to particular templated conformations of the polymer. Resonance Raman intensity analysis then provided insights on the excited state vibrational-mode-dependent reorganization, through simultaneous modelling of the band intensities and the absorption spectrum, as a function of the extent of interactions between the polymer and the ssDNA. Finally, we combined this information with ultrafast transient absorption experiments in the near- and mid-IR to understand the effect of structural templating on the excited state processes. We found that while certain ssDNA sequences can induce order in the conjugated polymer backbone through extensive interactions between the two partners in the complex, the templating scaffold does not seem to be a mere spectator but instead participates and affects the excited state behaviour. This is something that needs to be considered in the design of functional templated conjugated polymers for their suitability for particular optoelectronic applications.

About the speaker

Sophia Hayes is an Associate Professor in the Department of Chemistry, UCY and Director of the Molecular Spectroscopy Laboratory (MSL). Her expertise is in Molecular Spectroscopy, especially ultrafast spectroscopy (pump-probe techniques), resonance Raman (RR), and time-resolved RR applied to various chemical systems. She obtained her bachelor’s degree in chemistry (and Art!) from Luther College (Iowa, USA) and her PhD in Physical Chemistry from the University of Washington (Seattle, USA) under the supervision of Prof. Philip Reid. After a post-doctoral fellowship at UW in the same group, she moved to the University of Cambridge for a post-doctoral appointment in the Optoelectronics Group (Physics Department) under the supervision of Carlos Silva, where she started her work on conjugated polymers and their photophysical behaviour using ultrafast pump-probe spectroscopy. Her present work expands in two different fields, biophysics and organic semiconductors, with a common thread the understanding of interactions between molecules and their environment using vibrational spectroscopy as a structural probe.