Effects of Additives on the Morphology of Solution Phase Aggregates Formed by Active Layer Components of High-Efficiency Organic Solar Cells
journal contributionposted on 28.12.2011, 00:00 by Sylvia J. Lou, Jodi M. Szarko, Tao Xu, Luping Yu, Tobin J. Marks, Lin X. Chen
Processing additives are used in organic photovoltaic systems to optimize the active layer film morphology. However, the actual mechanism is not well understood. Using X-ray scattering techniques, we analyze the effects of an additive diiodooctane (DIO) on the aggregation of a high-efficiency donor polymer PTB7 and an acceptor molecule PC71BM under solar cell processing conditions. We conclude that DIO selectively dissolves PC71BM aggregates, allowing their intercalation into PTB7 domains, thereby optimizing both the domain size and the PTB7–PC71BM interface.