Self-Assembly of Squaraine Dyes: A Thermodynamic Exploration of Aggregation on Device Properties

S. Spencer, V. Murcia, P. Heaphy, C. Bougher, B. Conrad, S. Misture, J. Cody, C. Collison
Rochester Institute of Technology, US

Keywords: organic solar cell, small molecule, aggregates, squaraine, self-assembly

Summary:

Using a comprehensive experimental and theoretical approach, we present a set of materials from the squaraine family that can serve as a unique energetic probe of the bulk heterojunction. We demonstrate successful devices and tight macroscopic control of the nano-scale structure of these squaraines when they are spun-cast into a bulk heterojunction organic solar cell. They are easy to synthesize and cost-friendly, both monetarily and environmentally. Squaraines form very unique aggregates which have different optical and electronic properties allowing for probing of the bulk heterojunction, and we demonstrate with these probes that the most important step in the process of charge photogeneration is exciton dissociation at the BHJ interface.