Molecular Materials

Börjesson Research Group


Resonance energy transfer

Excitation energy transfer through dipole-dipole interactions can efficiently mediate energy between molecules at fairly large distances. In this so called Förster type energy transfer the transition dipole moments on the energy donor and acceptor couple so that excitation energy is transferred between the two molecules. The efficiency of the energy transfer depends not only on the strength of the transition dipole moments, but also on their relative orientation. Our research efforts aim at both studying this process at a fundamental level and also use it to increase the efficiency of molecular electronic devices.


Strong exciton-photon coupling

A common way of envision the creation of molecular orbitals is through the hybridization of atomic orbitals. It is perhaps less known that electronic states in molecules and atoms can hybridize with light or vacuum fields to create hybrid light matter states. So called strong exciton-photon coupling occurs when light-matter interactions are large, and it is manifested through new hybrid light-matter states called cavity polaritons. The pioneering work within this field, cavity quantum electrodynamics, was made in the 80’s by among others Haroch, who placed atoms in microwave cavities. In the beginning of the 90’s the strong couple regime was achieved also in the optical regime. In the earlier work atoms were used as active media, but later inorganic materials in both the form of semiconductors and quantum dots have been explored. Molecules can form even stronger exciton-photon coupling than atoms and inorganics, due to a larger transition dipole moment, but potential applications have just begun to be revealed. Our research efforts aims at exploring the phenomena at a fundamental level, and use it to generate organic molecular systems with fundamental new properties.


Molecular Switches

Molecular switches are capable of isomerizing between two different states, when exposed to an external stimulus such as light. The two isomers can have remarkably contrasting properties (e.g. electronic, optical, mechanical), which have made them popular in many applications. We have used the change in electronic properties between the two isomers as a light triggered on/off button in organic field effect transistors, and used non-isoenergetic isomers to capture and store solar energy. Our research efforts aims at developing new switches with improved properties as to expand the potential field of applications for this class of interesting molecules.


Copyright C 2015 Karl Börjesson | University of Gothenburg | Department of Chemistry and Molecular Biology. All Rights Reserved.

Mailing address

Karl Börjesson

Department of Chemistry and Molecular Biology,

University of Gothenburg

Kemivägen 10

412 96 Gothenburg Sweden


karl.borjesson (at)



Visiting address

Kemigården 4

Chemistry building, Campus Johanneberg

Room 8024

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