431917 Manipulating Organic Photovoltaic Thin Film Morphology through Interface Modification and Additives

Wednesday, November 11, 2015: 2:00 PM
251B (Salt Palace Convention Center)
Zach Seibers, Department of Energy Science and Engineering, University of Tennessee, Knoxville, TN and S. Michael Kilbey II, Departments of Chemistry and of Chemical and Biomolecular Engineering, University of Tennessee-Knoxville, Knoxville, TN

The conversion of sunlight to energy using organic photovoltaic devices (OPVs) is viewed as a promising route to sustainable energy generation. The drive to improve the power conversion efficiency (PCE) of OPVs has rightfully attracted a great deal of attention; however, overcoming the shortfall in PCE remains a significant challenge. While various factors such as inadequate hole transport mobility of donor-type conjugated polymers, limited solubility and miscibility with fullerene acceptors, and inefficient light harvesting are obstacles, controlling the morphology of the bulk heterojunction (BHJ) active layer remains a particularly thorny multi-dimensional problem. In this presentation, efforts to address this through the use of well-defined, end-functional poly(3-hexylthiophene)s (P3HTs) that allow interfacial layers that straddle the anode-BHJ interface will be described. Neutron reflectivity studies, which enable the laterally averaged depth profile of P3HT donor and PCBM acceptors in BHJ-like thin films to be measured, show that the interfacial “P3HT brush” layer impacts morphology, leading to a more uniform composition profile through the film. Coupled with various annealing strategies and the use of additives, these studies point to possibilities for tuning BHJ morphology and optimizing performance.

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See more of this Session: Conjugated Polymers
See more of this Group/Topical: Materials Engineering and Sciences Division