Joshua Karlsson

I completed my undergraduate education in chemistry at the University of York (UK) in 2013, followed by a postgraduate master’s degree in green chemistry at Imperial College London 2014 and a PhD in molecular photophysics at Newcastle University (UK) 2018. My research career proceeded at Newcastle University 2019-2022 followed by the University of Cambridge 2023.

My core expertise are in the realms of photochemistry and molecular photophysics, studying primary photoinduced processes for small molecular dyes relevant to environmental sensing, medical imaging and next-generation solar cells. Previous work included detailed interrogation of excited state properties for organic /inorganic chromophores pertinent to the far-red spectral range. This work was timely due to difficulties measuring external quantum efficiency of emissive dyes with traditional equipment in the 600-1000 nm region, which is nonetheless crucial for solar cells and medical imaging. This work involved developing bespoke instruments for the task. Extensive investigations were also carried out understanding the triplet excited state properties for the exciton multiplication process known as singlet exciton fission.

Since 2019, my expertise have broadened to photoelectrochemical devices for generating solar fuels (water-splitting and CO2 reduction), materials characterisation with atomic force microscopy and solar light harvesting materials using both photon up-conversion and down-conversion (resonance energy transfer and triplet-triplet annihilation respectively). More recent work has married my insight into fundamental photophysical processes with an in-operando understanding of practical solar energy conversion devices.

I joined Tampere University having been awarded a research fellowship by the Tampere Institute for Advanced Study as the first step in establishing an independent research direction. My current research project carries the title: “Controlling the Photostability of Next Generation Solar Cells”, where the objective is to understand fundamental photochemical processes leading to photodegradation of light-absorbing materials in next-generation solar cell technologies (dye-sensitised solar cells, organic photovoltaics and perovskite solar cells).

Understanding the mechanistic origin and change in materials properties during photodegradation requires a wholistic approach and faces the grand challenge of studying photodegradation of an operational solar cell device. This work is crucial in designing more durable third-generation solar cell technologies to improve technology transfer and thus facilitate the transition a sustainable electricity generation system.

Project summary: https://youtu.be/wjIPsGf7wFY?si=VsFh71pGRN1B8cbZ

Absorption/fluorescence spectroscopy, time-resolved optical spectroscopy including time-correlated single photon counting, laser flash photolysis and ultrafast transient absorption spectroscopy, atomic force microscopy, gas/liquid chromatography, mass spectrometry, electrochemistry

Physical chemistry, molecular photophysics, photochemistry, optical spectroscopy, organic dyes, microscopy, bio-imaging, solar cells, solar fuels, photodegradation/photostabilisation.

1. Karlsson, J.K., Cerpentier, F.J., Lalrempuia, R., Appleby, M.V., Shipp, J.D., Chekulaev, D., Woodford, O., Weinstein, J.A., Pryce, M.T. and Gibson, E.A., 2023. Ruthenium–rhenium and ruthenium–palladium supramolecular photocatalysts for photoelectrocatalytic CO 2 and H+ reduction. Sustainable Energy & Fuels, 7(14), pp.3284-3293.
2. Toupalas, G., Karlsson, J., Black, F.A., Masip‐Sánchez, A., López, X., Ben M’Barek, Y., Blanchard, S., Proust, A., Alves, S., Chabera, P. and Clark, I.P., 2021. Tuning Photoinduced Electron Transfer in POM‐Bodipy Hybrids by Controlling the Environment: Experiment and Theory. Angewandte Chemie International Edition, 60(12), pp.6518-6525
3. Kavanagh, M.A., Karlsson, J.K., Colburn, J.D., Barter, L.M. and Gould, I.R., 2020. A TDDFT investigation of the Photosystem II reaction center: Insights into the precursors to charge separation. Proceedings of the National Academy of Sciences, 117(33), pp.19705-19712
4. Karlsson, J.K., Laude, A., Hall, M.J. and Harriman, A., 2019. Photo‐isomerization of the Cyanine Dye Alexa‐Fluor 647 (AF‐647) in the Context of dSTORM Super‐Resolution Microscopy. Chemistry–A European Journal, 25(65), pp.14983-14998
5. Karlsson, J.K., Atahan, A., Harriman, A., Tojo, S., Fujitsuka, M. and Majima, T., 2018. Pulse radiolysis of TIPS-pentacene and a fluorene-bridged bis (pentacene): Evidence for intramolecular singlet-exciton fission. The Journal of Physical Chemistry Letters, 9(14), pp.3934-3938.