Abstract

Organic solar cells (OSC) are an emerging technology under the umbrella of renewable solar energy. While various research groups have demonstrated organic solar cells with champion efficiency over 20%, the materials used must be processed in problematic (e.g. expensive, toxic) solvents, often halogenated and aromatic like chlorobenzenes. The purpose of this work is to develop green solvent processable polymers to avoid the problematic solvents by either (i) finding a new green solvent that can process already existing high-performance polymers, such as PTQ-10, a donor often used in OSC, or (ii) synthesizing new side chains for increased green processability. To do this we are using Hansen Solubility Parameters (HSPs) to model solubility of solvents and solutes on a three dimensional graph. HSP values intermolecular forces mathematically and allows you to plot the strength of intermolecular forces. With these plots, this work will compare HSP values from PTQ-10 and green solvents to find new solvents to pair with PTQ-10. Previous works have utilized oligo(ethylene glycol) (OEG) side chains to modify PTQ-10’s solubility, but it caused a decrease in efficiency of the solar cell. Building off of this work, we decided to work on adding side chains with a long alkyl segment capped with either an ionic or polar head to increase the polarity of the HSP values. With PTQ-10’s HSP values we created a list of potential solvents that are safer than the halogenated and/or aromatic solvents currently used. The new side chain was found to have complications that inhibited the formation of the novel PTQ-10 derivative.

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