Abstract
Electronic excited states with spin-triplet character play a key role in the operation of optoelectronic devices fabricated from organic semiconductors, including organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). In general, spin-triplet excitations are optically dark and lie deeper in energy than their bright spin-singlet counterparts and can thus be considered low energy trap states that are detrimental to device performance. In my talk, I will discuss some of our recent work employing ultrafast optical spectroscopy to understand the formation mechanisms and photophysics of triplet excitons in organic semiconductor devices. This will include the impact of triplet excitons on OPV performance and potential strategies to mitigate this, as well as understanding how vibrational coupling drives the intersystem crossing processes in multiple resonance thermally-activated delayed fluorescence (MR-TADF) emitters.
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Brief Bio
Alex Gillett is currently an Assistant Professor at Linkoping University in Sweden. Before this, he completed his PhD under the supervision of Professor Sir Richard Friend at the University of Cambridge in 2019, which was followed by a postdoctoral stay in the same group. He began his independent career with the award of a Leverhulme Early Career Fellowship at Cambridge in 2022. In 2024, he was awarded research grants by the Wallenberg Academy Fellows program and Swedish Research Council and moved to his current position at Linkoping University in the same year. Alex's research focuses on the development and application of ultrafast optical spectroscopy techniques to study the fundamental photophysics of organic semiconductor materials. He has a particular interest in high spin excitations and their role in optoelectronic device function, as well how vibrational couplings modulate the photophysics of organic molecules.
