On the morphology of polymer-based photovoltaics

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 50; no. 15; pp. 1018 - 1044
• Main Authors: Liu, Feng, Gu, Yu, Jung, Jae Woong, Jo, Won Ho, Russell, Thomas P.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.08.2012
• Subjects: Commonality; conjugated polymers; Control systems; Devices; diffusion; Evolution; miscibility; Morphology; neutron scattering; Optimization; organic photovoltaics; phase separation; Photovoltaic cells; Solar cells; X-ray scattering
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.23063

We review the morphologies of polymer‐based solar cells and the parameters that govern the evolution of the morphologies and describe different approaches to achieve the optimum morphology for a BHJ OPV. While there are some distinct differences, there are also some commonalities. It is evident that morphology and the control of the morphology are important for device performance and, by controlling the thermodynamics, in particular, the interactions of the components, and by controlling kinetic parameters, like the rate of solvent evaporation, crystallization and phase separation, optimized morphologies for a given system can be achieved. While much research has focused on P3HT, it is evident that a clearer understanding of the morphology and the evolution of the morphology in low bad gap polymer systems will increase the efficiency further. While current OPVs are on the verge of breaking the 10% barrier, manipulating and controlling the morphology will still be key for device optimization and, equally important, for the fabrication of these devices in an industrial setting. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 Polymer‐based photovoltaics attract much attention due to their promising applications. In this review, we focus on the morphology study of polymer solar cells. Different categories of conjugated polymers and their blends with fullerene derivatives are discussed. Several key parameters such as crystallinity, miscibility, size of phase separation, and vertical phase segregation that determines the morphology and device performance are analyzed. These understandings of morphology will help material scientists to further increase the performance of plastic solar cells.