Master Thesis "Rationalizing the impact of the processing conditions on the morphology of the absorber layer in organic solar cells"

Subject

Organic solar cells (OSC) belong to the emerging photovoltaic technologies that can contribute to the energy transition in the near future. Compared to silicon devices, these solutionprocessed solar cells are low cost and eco-friendly, and can be made flexible or semitransparent. The fabrication process is known to play a crucial role in their performance. In particular, a complex demixed phase nanomorphology arise upon drying of the deposited solution. However, the process-structure relationship is still poorly understood. The objective of this master thesis is to study the impact of the processing conditions on the morphology of the dry film with the help of Phase-Field simulations. Thereby, four cases that are representative of real OSC blends will be considered (one or two crystalline materials, compatible or incompatible donor-acceptor blend). Several process parameters will be varied, in particular the evaporation rate, the initial wet film thickness and concentration, the interactions of the solvent with both donor and acceptor materials, and pre-crystallization.

Your tasks

Perform systematic simulations of the drying process for ternary blends made of one polymer donor, one small-molecule acceptor and one solvent.
Analyze the final morphologies as well as the morphology formation mechanisms
Establish physical relationships between the process parameters and the dry film morphology, and propose process design rules for obtaining the optimal film morphology, depending on the donor-acceptor blend properties
Report your results in a written report and oral presentations