Discipline: 
Physics
Status: 
Available
Level: 
PhD Project
Level: 
Honours Project
Supervisor(s): 
Dr Ivan Kassal
Organic solar cells differ from conventional (inorganic) ones in several ways. Most importantly, organic materials are disordered, meaning that charges tend to be localised and move by hopping---quite distinct from the band transport in inorganic devices. 
 
The localisation of the electron and the hole increases the Coulomb attraction between them, making it harder to separate them and produce an electric current. Indeed, it is still unknown exactly how the charges overcome their considerable electrostatic attraction. 
 
This theoretical project will explore how strong the Coulomb attraction really is. Conventional models predict very strong binding, but they usually ignore effects such as moderate delocalisation, entropy, and local electric fields. We aim to develop a more complete model that will be able to explain why some organic solar cells have unusually efficient charge separation while others lag behind.