Nanoscale Assembly of Semiconducting Polymers and Fullerenes for Photovoltaic Applications

Seminar series
Inorganic Chemistry
Wed, May 28 4:30pm
Cram Conference Room, 3440 Mol Sci
Speaker Rachel Huber
Department of Chemistry and Biochemistry

This talk will focus on control of nanoscale film morphology and self-assembly of semiconducting polymers and fullerenes for use in photovoltaic devices. These materials are of interest to the solar community due to their ease of processability and low cost. In this talk, we will focus on three different topics. First, we will explore how the crystallinity of different molecular components of a blended film affects device performance. Next, we will examine a hydrogel network formed from a charged amphiphilic polymer, poly(fluorene-alt-thiophene) (PFT). This polymer self-assembles into rod-like structures in water and also shows improved conductivity in dried films due to its assembled structure. Here we use small angle X-ray scattering and TEM to confirm the nanoscale rod-like assembly, we then employ rheology to study how the three dimensional network is held together. The final section of this talk will examine the addition of a water-soluble fullerene, C60-N,N-dimethylpyrrolidinium iodide, to PFT as a step towards water-processable organic solar cells. Photoexcitation of aqueous assemblies of cationic polymers and fullerenes result in the formation of free charge carriers (polarons). These separated charge carriers are stable for days, which is unprecedented in polymer/fullerene solutions. All of these studies combine to show how the assembly of conjugated organic molecules has potential to improve device performance.