Measuring ultrafast exciton delocalisation in organic solar cell material

Organic semiconducting polymers are a topic of extensive research for their use in organic solar cells, thin film transistors and more recently energy storage devices. In organic solar cells an initial hot exciton is created through absorption of a visible photon and rapidly undergoes delocalisation across multiple polymer chains to the lowest energy delocalised state.

This rapid delocalisation is the origin of the charge transfer process and a vital step in the energy transfer. Through configuration of the polymer molecular structure the charge transfer can be enhanced, leading to increases in overall photovoltaic efficiency. P3HT is an established organic photovoltaic material, with one of the highest recorded efficiencies.

This PhD project will focus on exploring the ultrafast charge dynamics in organic semiconductors, including polythiophenes (e.g. P3HT) and a recently discovered class of polymers, referred to as Non-Fullerene Acceptors (NFA), which show enhanced organic photovoltaic (OPV) efficiency. This PhD project has the following objectives: 1.

Extend time resolved C K edge measurements on P3HT to the S K edge to reconstruct the full evolution of exciton behaviour by extending the delay range. 2. Explore different morphologies of P3HT polymers to investigate interchain separation and its impact on delocalisation. 3. Study the exciton behaviour in new NFA organic photovoltaics, such as Y6 to deliver the first time resolved XFEL study tracking exciton creation in fused ring structures.

Organic semiconducting polymers are a topic of extensive research for their use in organic solar cells, thin film transistors and more recently energy storage devices. In organic solar cells an initial hot exciton is created through absorption of a visible photon and rapidly undergoes delocalisation across multiple polymer chains to the lowest energy delocalised state.

This rapid delocalisation is the origin of the charge transfer process and a vital step in the energy transfer. Through configuration of the polymer molecular structure the charge transfer can be enhanced, leading to increases in overall photovoltaic efficiency. P3HT is an established organic photovoltaic material, with one of the highest recorded efficiencies.

This PhD project will focus on exploring the ultrafast charge dynamics in organic semiconductors, including polythiophenes (e.g. P3HT) and a recently discovered class of polymers, referred to as Non-Fullerene Acceptors (NFA), which show enhanced organic photovoltaic (OPV) efficiency. This PhD project has the following objectives: 1.

Extend time resolved C K edge measurements on P3HT to the S K edge to reconstruct the full evolution of exciton behaviour by extending the delay range. 2. Explore different morphologies of P3HT polymers to investigate interchain separation and its impact on delocalisation. 3. Study the exciton behaviour in new NFA organic photovoltaics, such as Y6 to deliver the first time resolved XFEL study tracking exciton creation in fused ring structures.