Results obtained with fast-scanning calorimetry sample holder.

<p>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.</p

Sketch of the experimental setup for transmission X-ray ptychography.

<p>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.</p

X-Ray Nanoscopy of a Bulk Heterojunction - Fig 4

<p>(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 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158345#pone.0158345.e007" target="_blank">Eq 5</a>. The fitted parameters of <i>L</i> = 6.0 μm and <i>D</i> = 7 x 10⁻¹² cm² s^-1 provide excellent agreement between the experimental data and the model.</p

Improved Photovoltaic Performance of a Semicrystalline Narrow Bandgap Copolymer Based on 4<i>H</i>-Cyclopenta[2,1-<i>b</i>:3,4-<i>b</i>′]dithiophene Donor and Thiazolo[5,4-<i>d</i>]thiazole Acceptor Units

A solution processable narrow bandgap polymer composed of alternating 2,5-dithienylthiazolo­[5,4-<i>d</i>]­thiazole and asymmetrically alkyl-substituted 4<i>H</i>-cyclopenta­[2,1-<i>b</i>:3,4-<i>b</i>′]­dithiophene units (<b>PCPDT-DTTzTz</b>) was synthesized by Suzuki polycondensation and the donor–acceptor copolymer was thoroughly characterized. Thermal analysis and X-ray diffraction studies disclosed the semicrystalline nature of the material. When blended with PC₇₁BM and integrated in bulk heterojunction organic solar cells, a moderate power conversion efficiency of 2.43% under AM 1.5 G (100 mW/cm²) conditions was obtained. However, upon purification of the semiconducting copolymer by preparative size exclusion chromatography, a noticeable rise in power conversion efficiency to 4.03% was achieved. The purified polymer exhibited a relatively high field-effect carrier mobility of 1.0 × 10^–3 cm²/(V s). The active layer morphology was explored by atomic force microscopy and transmission electron microscopy studies, showing phase segregation on the nanometer scale