Vertical Morphology Characterizations

The distribution of components in BHJ thin-films normal to the surface of the film is also critical in defining the performance of the material. In the simplest extreme, if there is a preferential segregation of one component to an electrode interface, device performance can be poor even with an idealized morphology in the remaining part of the BHJ active layer. Given that charge transfer and collection occur at the electrode, transport to these interfaces requires transport normal to the surface of the film. Normally, the BHJ layer is 100-200 nm in thickness. Consequently, methods are needed to assess composition profiles normal to the film surface or techniques must be used to examine cross-sections normal to the film surface. In the latter case, cryo-microtoming or focused ion beam (FIB) are required. 

Other methods, sueh as variable-angle spectroscopic ellipsometry (VASE), can be used to obtain a depth profile of the BHJ active layers in thin-films. However, the proper modeling of the refractive indices of BHJ components and fitting is challenging, and one must contend with the fact that most polymers are highly absorbing for wavelengths in the visible spectrum.  

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Solid surfaces have been found to exhibit fractal morphology. A study of the quality and accuracy of the methods based on frequency analysis for the fractal characterization of solid surfaces was carried out by STM. The study was based on computer simulation of images of fractal surfaces. Measurement of the fractal character of a surface in the microscope range has specific problems. The most important is that the images of a given solid surface arise from the projections of the surface topography in which the vertical dimension is unknown, whereas from both STM and AFM we can obtain the vertical dimensions. 

Kim and Park presented the first reported use of vertically oriented titanium oxide nanotube/PPy nanocomposites to increase the SC of TiO -based energy-storage devices [64]. To increase their electrical storage capacity, the TiO nanotubes were coated with PPy and their morphologies were characterized. The incorporation of PPy increased the SC of the TiO nanotubes-based supercapacitor system, due to their increased surface area and additional pseudo-capacitance. 

According to these results, HI, JMA and MZW, at least, are involved in the morphological patterns characterizing the species adapted to feed mainly on fruits and other non-fibrous soft material. In the three-dimensional, perpendicular-edges polyhedron containing all the species, selective feeders occupy a small region around one of its eight vertices. 

Scanning electron microscopy (SEM) (characterization) In SEM, the secondary electrons from an electron-bombarded surface are used to form an image of the surface morphology. The magnification can be varied from several hundred diameters to 250000 diameters with high lateral and vertical resolutioa... 

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