291902 Controlling Morphology of Bulk Heterojunction Polymer/Fullerene Mixtures
Title: Towards Solar Cell Efficiencies: Controlling Morphology of Bulk Heterojunction Polymer/Fullerene Mixtures
Coping with the growing need for energy in an inexpensive, sustainable manner is an imperative issue that will have many answers, some local, for which solar energy will serve a growing niche. Organo photovoltaic (OPV) cells offer solutions for key aspects of that market that require lightweight or flexible materials (e.g. solar collection in a wearable fabric). Manipulation of morphology of P3HT (polymer) and PCBM (fullerene derivative) mixtures can produce bulk heterojunctions with improved power conversion efficiency (PCE). This research focuses on understanding the thermodynamic stability of the morphology of P3HT/PCBM mixtures in various solvent/antisolvent mixtures typical for processing/deposition of the photoactive polymer layer in organophotovoltaics. The method used for this experiment was to dissolve either P3HT or PCBM in solvent, then incorporate an anti-solvent to study control of aggregation. Then the mixtures were manipulated in the same manner to understand if solubility could be predicted independently. Visual spectroscopy was used to detect maximum wavelength (WL) at which aggregation took place. Early X-ray diffraction (XRD) studies are also presented to determine the impact of such processing on polymer crystallinity. Further experiments will determine whether PCBM nucleates P3HT crystals.