DUGi

Modelització de materials per a cel·les fotovoltaiques

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@14656

At present there is an increase of the energy generated by means of renewable energies. One of the main sources of renewable energy is solar energy, which is produced by photovoltaic cells. One of the most recent types of photovoltaic cells is the organic photovoltaic cells (OPVs), which have interesting mechanical characteristics but have a relatively low yield The low performance of the OPVs is their main problem and to improve this performance one has to investigate and deeply understand the mechanism of the operation of these solar cells. In order to achieve this there is a problem that has to be prepared first, the material that compose the cell is amorphous and, therefore, it is difficult to investigate the structure experimentally. Since solving the structure is fundamental to learn how OPVs operate accurately then we will use computational methods per resolve the structure. The system to be studied consists of molecules p-DTS (FBTTh2) 2 and PC71BM. Since the molecules are very large It’s not possible simulate the system using a very precise quantum method because calculations would take too long, therefore we resort to force field methods that are faster but less accurate. In order for the results of the force field methods to be the closest to the results of the quantum methods, we will perform a parameterization. To do this parameterization we will divide the system into different parts: the molecule p-DTS(FBTTh2)2 will be divided into three fragments and the molecule PC71BM will be simplified to C70 fullerene. The parameterization itself will be based on parameterizating the rotation of the dihedral angles between the aromatic rings of the three fragments of the molecule p-DTS (FBTTh2)2, since this is the most flexible part of the fragments. It will also parameterize the stacking in the three fragments. Once the p-DTS(FBTTh2)2 molecule is parameterized, the C70 molecule will be parameterized. Specifically, only the stacking between two molecules of C70 fullerene will be parameterized