Comparing morphology in dip-coated and spin-coated polyfluorene:fullerene films

University essay from Karlstads universitet/Institutionen för ingenjörs- och kemivetenskaper

Abstract:

Unsustainable energy sources are running out and global warming is getting worse. Therefore the need for renewable energy sources is growing. Solar cells are a popular options used as an energy source. Most popular are the inorganic photovoltaic cells. With their high efficiency and long lifetime, they make a very good energy source. Unfortunately the costs for inorganic solar cells are rather high. Organic solar cells can make a good replacement for inorganic photovoltaic. They are easy to make, light and rather cheap.

In this thesis, the morphology of a model system of the active layer of organic solar cells will be discussed, using dip coating as well as spin coating as a technique to prepare the films. The films consist of a blend of poly(9,9-dioctylfluorenyl-2,7-diyl) and [6,6]-phenyl C61-butyric acid methyl ester in different ratios and different solvents. The films that were made were prepared by spin coating or dip coating a glass substrate. After analysing the samples using atomic force microscopy, fluorescence spectroscopy and absorption spectroscopy it was clear that the morphology, as well as the position of the polymer chains can be influenced by using different dipping speeds, ratios or solvents.

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