Ilia Sokolovski awarded the Gust. Komppa Prize for his doctoral thesis in chemistry

A total of 11 dissertations were submitted to the Gust. Komppa Prize competition by various universities. The press release of the Finnish Chemical Magazine states that both winning dissertations represent a very high scientific level, and they consist of several research articles of high impact, representative of their own field.

- The high standard of the dissertation is the result of close collaboration and excellent supervision by Professor Gerrit Groenhof. This recognition is a great honor and a significant encouragement to continue my research work, says Ilia Sokolovskii.

More efficient energy transport in organic solar cells

Organic solar cells offer a promising alternative to traditional silicon-based solar cells, which currently dominate the global solar power market. The advantages of organic solar cells include lower manufacturing costs, light weight, flexibility, and abundance of materials, but wider use is still limited by their lower efficiency.

- The main challenge of organic materials is related to energy transport. Due to structural disorder, excitation carriers move from one molecule to another through incoherent hops and this is quite inefficient. As a consequence, the efficiency of commercially produced organic solar cells is significantly lower than that of silicon-based counterparts, says Sokolovskii.

To address this challenge, mixing molecular excitations with confined light modes of optical cavities has been proposed. In the limit of strong interaction, these two constituents hybridize into quasiparticles called polaritons, which inherit properties of both molecular excitons and cavity light modes. Owing to a high group velocity of polaritons, their propagation should be ballistic and long-range. 

- In my doctoral thesis, I examined this phenomenon from an atomic perspective using a multiscale molecular dynamics model. The structure of molecules and their chemical environment were described by a combination of quantum mechanics and classical molecular mechanics, explains Sokolovskii.

Supercomputer simulations provide a view at the atomic level

The research involved simulations on supercomputers Mahti and Puhti which are hosted by the Finnish CSC – IT Center for Science. Based on the simulation results, Sokolovskii proposed a general mechanism for enhancing energy transport in cavities and analyzed how the transport properties change when the dispersion of polaritons and the quality factor of the cavity are adjusted.

- The results provide new insights into the functioning of light-matter systems. This helps us understand how energy transfer in organic materials can be improved, potentially paving the way towards the development of a new type of solar cells and optical devices based on strong light-matter coupling, explains Sokolovskii.

Ilia Sokolovskii defended his thesis at the University of Jyväskylä in November 2024. His thesis supervisor was Professor Gerrit Groenhof from the University of Jyväskylä. Sokolovskii is currently a postdoctoral researcher at the University College London and continues to work on molecular polaritonics.

The dissertation "Multiscale Molecular Dynamics Simulations of Enhanced Excitation Energy Transport in Organic Microcavities” can be read on the JYX publication archive: https://jyx.jyu.fi/handle/123456789/97703.