Exciton Seminar: Dr Ivan Kassal
The Exciton Science Seminar on Friday 30 August 2019 at the University of Sydney will feature guest speaker Ivan Kassal from The University of Sydney Nano Institute.
Dr Kassal will present on "Transport of partially delocalised charges and excitons". See abstract below.
The afternoon will feature presentations from Exciton Science's ECRs and PhD students. A draft schedule for the day is below.
Please register at EventBrite by Monday 26 August for catering purposes.
The event is for Exciton Science members (including CIs, PIs, AIs, researchers and students.). Those travelling from interstate should speak to their node administrators for support with travel.
ABSTRACT:
Transport of partially delocalised charges and excitons
Ivan Kassal, School of Chemistry, The University of Sydney
Charge and exciton transport are well understood in two extremes: in highly ordered materials, transport is by band conduction, while in highly disordered ones, it is by hopping. In moderately disordered materials, the approximations valid in either extreme break down, making it difficult to accurately model the conduction process. Materials where this is an issue include organic semiconductors, metal organic frameworks, hybrid perovskites, and quantum dots. For example, charges and excitons in organic semiconductors are usually assumed to be localised onto individual molecules (or segments of polymers), but intermolecular couplings mean that there is usually some (partial) delocalisation across multiple molecules. Theoretically describing the movement of partially delocalised carriers is difficult, because it depends on a complicated interplay of energetic disorder, quantum-mechanical couplings, and polaron formation.
We report a new method that is able to describe the motion of partially delocalised charges and excitons in all regimes of disorder. We also implement numerical innovations to allow us to work in three dimensions, a regime that had proven too complicated for all comparable approaches. Our results reveal new, basic physics of transport in organic semiconductors, explain why mobilities predicted by traditional kinetic Monte Carlo are usually too low, and show how three-dimensional calculations capture effects missing in lower-dimensional approximations.
