Fig 1.
Sketch of the experimental setup for transmission X-ray ptychography.
Coherent diffraction patterns are recorded by a 2D detector for a set of partially overlapping scanning positions, allowing numerical reconstruction of the projected complex-valued image of the sample.
Fig 2.
Reconstructed phase contrast high-resolution projections of P3HT/PCBM layers, all measured at room temperature.
a) Non-isothermally annealed; b-d) Isothermally annealed with increasing annealing time of 60 s, 720 s and 7500 s at 127°C. e) Estimated volume fraction (χ) as a function of position estimated along the five lines indicated in d). The volume fraction gradient for the five different regions is in the range of 0.14 ± 0.05 μm-1. For readability, the curves are vertically offset. Note that the intensity scale differs between a-c) and d), as the aggregation was much more pronounced in the latter case. The red arrow in (d) indicates an area assumed to contain the lowest PCBM concentration of 4%.
Fig 3.
Results obtained with fast-scanning calorimetry sample holder.
a) Optical micrograph of the active area on the electronic chip. The central patch is the P3HT-PCBM sample. b-f) Reconstructed phase-contrast high-resolution ptychography projections, with (b) showing the area corresponding to the section marked by the outlined white square in (a). c) Projection for as-cast film, showing that the deposition process has induced a certain morphology. d) Morphology after erasing the thermal history by shortly visiting the melt, showing an essentially featureless image. e),f) Images obtained after 60 s and an additional 660 s (total of 720 s), respectively, of annealing at 400 K, clearly showing that a coarser morphology develops with time. All images were collected at room temperature to reduce problems with radiation damage.
Fig 4.
(a) Reconstructed phase contrast high resolution projection of P3HT/PCBM layer isothermally annealed for 7500 s at 127°C. The black line in the projection image corresponds to the PCBM concentration profile shown in (b). The red curve in (b) shows the fitting analysis applied to the PCBM concentration profile using Eq 5. The fitted parameters of L = 6.0 μm and D = 7 x 10−12 cm2 s-1 provide excellent agreement between the experimental data and the model.