Influence of substrate on crystallization in polythiophene/fullerene blends

He, Christine; Germack, David S.; Kline, R. Joseph; DeLongchamp, Dean M.; Fischer, Daniel A.; Snyder, Chad R.; Toney, Michael F.; Kushmerick, James G.; Richter, Lee J.

doi:10.1016/j.solmat.2010.12.035

Cited by 43 publications

(63 citation statements)

References 35 publications

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“…The fullerene‐rich phase also shows a decrease at both interfaces in the uncapped sample. The increase in fullerene content at the interfaces is consistent with the reflectometry measurements made here and in other measurements . The presence of the metal seems to affect not only the composition at the metal interface, but also the substrate interface.…”

Section: Resultssupporting

confidence: 91%

Material profile influences in bulk-heterojunctions

Roehling

Rochester

et al. 2014

J. Polym. Sci. Part B: Polym. Phys.

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The morphology in mixed bulk-heterojunction films are compared using three different quantitative measurement techniques. We compare the vertical composition changes using high-angle annular dark-field scanning transmission electron microscopy with electron tomography and neutron and x-ray reflectometry. The three measurement techniques yield qualitatively comparable vertical concentration measurements. The presence of a metal cathode during thermal annealing is observed to alter the fullerene concentration throughout the thickness of the film for all measurements. However, the absolute vertical concentration of fullerene is quantitatively different for the three measurements. The origin of the quantitative measurement differences is discussed.

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Section: Resultssupporting

confidence: 91%

Material profile influences in bulk-heterojunctions

Roehling

Rochester

et al. 2014

J. Polym. Sci. Part B: Polym. Phys.

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“…These studies have largely relied on grazing incidence X-ray scattering (GIXS), which has also been used to show how extrinsic parameters such as the material processing conditions, 10−13 and the polymer−substrate interface, 14,15 impact the orientation of polymer crystallites relative to the device substrate. In parallel, several π-conjugated systems have been found to yield distinct GIXS patterns, and ordering footprints in thin films, 2,3,16 independently of processing conditions and substrate effects.…”

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confidence: 99%

Dependence of Crystallite Formation and Preferential Backbone Orientations on the Side Chain Pattern in PBDTTPD Polymers

Labban

Warnan

Cabanetos

et al. 2014

ACS Appl. Mater. Interfaces

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Alkyl substituents appended to the π-conjugated main chain account for the solution-processability and film-forming properties of most π-conjugated polymers for organic electronic device applications, including field-effect transistors (FETs) and bulk-heterojunction (BHJ) solar cells. Beyond film-forming properties, recent work has emphasized the determining role that side-chain substituents play on polymer self-assembly and thin-film nanostructural order, and, in turn, on device performance. However, the factors that determine polymer crystallite orientation in thin-films, implying preferential backbone orientation relative to the device substrate, are a matter of some debate, and these structural changes remain difficult to anticipate. In this report, we show how systematic changes in the side-chain pattern of poly(benzo[1,2-b:4,5-b']dithiophene-alt-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers can (i) influence the propensity of the polymer to order in the π-stacking direction, and (ii) direct the preferential orientation of the polymer crystallites in thin films (e.g., "face-on" vs "edge-on"). Oriented crystallites, specifically crystallites that are well-ordered in the π-stacking direction, are believed to be a key contributor to improved thin-film device performance in both FETs and BHJ solar cells.

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“…The broadness of this feature suggests that the coherent domain size is a few fullerene molecules. If peaks in the X-ray diffraction are present, they are usually caused by micron-scale PCBM crystals that grow when the PCBM glass is heated above its glass transition temperature, especially on certain substrates [74], which is considered detrimental to the power conversion efficiency. Interestingly, the published crystal structures of PCBM contain solvent molecules, when either CB or DCB is used [75].…”

Section: Solution-processable Electron Acceptorsmentioning

confidence: 99%

Organic Photovoltaics

DeLongchamp

2015

Semiconductor Materials for Solar Photovoltaic Cells

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Organic photovoltaics (OPV) describes a group of technologies wherein the active layer of a solar cell is composed of hydrocarbon-based organic materials [1][2][3]. OPV occupies a special niche among solar energy technologies in that it could potentially satisfy the growing energy needs of the world with a product that is sustainable, elementally abundant, and cheaply manufactured. OPV cells have recently seen a dramatic uptick in reported efficiencies, with power conversion efficiencies reaching ≈11 %, as shown in Fig. 6.1 [4,5]. These increases in power conversion efficiency have largely been driven by the development and discovery of new OPV active layer materials and new ways to process them. The technology has gained significant commercial attention over the past decade, as its unique attributes merit consideration for a place in the landscape of distributed energy generation devices [6]. Some of OPV advantages include a flexible form factor and facile processing, either from fluids or from vacuum deposition.At least two different device designs are often regarded as OPV technologies. The first is based on a solid-state OPV cell, having typically two organic semiconductors in a bilayer or distributed heterojunction arrangement. The second type, which will not be addressed in this chapter, is more typically called a dye-sensitized solar cell (DSSC) [7], which relies on a mesoporous electron conductor that is typically inorganic, a sensitizing dye, and an ion-conducting redox electrolyte. Unlike organic heterojunctions, the DSSC contains liquid and thus faces challenges in packaging and limited flexibility.The first report of a solid-state OPV cell was as early as 1959, when a photovoltaic effect in ≈10-μm-thick anthracene crystals was reported [8].

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Influence of substrate on crystallization in polythiophene/fullerene blends

Cited by 43 publications

References 35 publications

Material profile influences in bulk-heterojunctions

Material profile influences in bulk-heterojunctions

Dependence of Crystallite Formation and Preferential Backbone Orientations on the Side Chain Pattern in PBDTTPD Polymers

Organic Photovoltaics

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