Water-based polymer nanoparticles for sustainable organic solar cells

In the world transition towards a renewable energy production, solar PV is emerging as the most cost-effective option. However concerns arise regarding manufacturing costs, materials, and end-of-life disposal of solar panels. This scenario has stimulated the development of organic solar cells (OSCs), in which organic semiconductors act as the most efficient and environmental-friendly material for photovoltaic purposes. New emerging approaches on OSC active layer processability have been investigated because of the possibility of further decreasing the environmental impact, especially in the perspective of technology up-scaling. The bulk heterojunction of donor and acceptor polymers is commonly coated using chlorinated organic solvents. Their toxicity to environment and humans has led to the improvement of strategies that involve the replacement of organic solvents with water, relying on the tendency, for conjugated polymers, to form nanoparticles (NPs) aqueous dispersions. During this curricular internship, my attention was directed towards the fabrication and characterization of organic solar cells. I worked on the optimization of the internal donor-acceptor morphology of the NPs in binary and ternary blends such as P3HT:o/eh-IDTBR, PTQ10:Y6 and PTQ10:Y6:PC61BM, activity that was based on the analysis of the interfacial tension between them. I demonstrated that following this strategy is possible to enhance the PCE of the solar cells reaching values close to those obtained with processing in chlorinated solvents. Part of my work has focused on testing the thermal stability of P3HT:eh-IDTBR active layer and MoO3 hole carrier layer. This evaluation was specifically aimed at determining their suitability for the deposition of a transparent top electrode through atomic layer deposition that operates at the temperature conditions tested. Its prospective application is the fabrication of a hybrid system capable of pairing in tandem, an organic solar cell and Si-based one.