Plastic Solar Cells and X-rays:Elucidating the Structure-Performance Relationship in Organic Photovoltaics (OPVs) by Grazing Incidence X-Ray Scattering

ABSTRACT: Since the introduction of the Bulk Heterojunction (BHJ) architecture in the mid 90s, organic photovoltaic devices have made steady progress toward improved power conversion efficiency, and are now poised to move from niche products to large scale commercial applications. In the BHJ, the photoactive layer consists of electron donor and acceptor materials in a bicontinuous phase blended on the nanoscale. Grazing incidence x-ray scattering, capable of characterizing thin film nanomorphology of surfaces and interfaces, has emerged as a key technique for investigating OPV materials. The hierarchical variety of lengthscales present in OPV materials requires both grazing incidence small- and wide-angle x-ray scattering, the latter recently enabled by improvements to the GISAXS instrument at 8-ID-E of the Advanced Photon Source. I will describe grazing-incidence studies at 8-ID-E that have contributed toward unraveling the complex relationship between OPV materials, processing and performance.