Wet Imprinting of Channel-Type Superstructures in Nanostructured Titania Thin Films at Low Temperatures for Hybrid Solar Cells.

Hierarchically structured titania films, exhibiting interconnected foam-like nanostructures and large-scale channel-type superstructures, were achieved in an energy-saving way at low temperatures by a polymer template-assisted sol-gel synthesis in combination with a wet-imprinting process. The surface morphology was probed with scanning electron microscopy and atomic force microscopy, whereas the inner morphology was characterized with grazing incidence small-angle X-ray scattering measurements. Compared to the initial hybrid films, the titania films showed reduced structure sizes caused by removal of the polymer template.

Codependence between Crystalline and Photovoltage Evolutions in P3HT:PCBM Solar Cells Probed with in-Operando GIWAXS.

We address the correlation between the crystalline state of photoactive materials in a model organic solar cell based on poly(3-hexylthiophene-2,5-diyl):phenyl-C-butyric acid methyl ester (P3HT:PCBM) and the photovoltage in an in-operando investigation. I-V curves are simultaneously measured together with grazing incidence wide-angle X-ray scattering probing the crystalline state of the device active layer as a function of the operation time. The results show a high degree of correlation between open-circuit voltage V and the crystalline state of P3HT.

Effect of Blend Composition and Additives on the Morphology of PCPDTBT:PC71BM Thin Films for Organic Photovoltaics.

The use of solvent additives in the fabrication of bulk heterojunction polymer:fullerene solar cells allows to boost efficiencies in several low bandgap polymeric systems. It is known that solvent additives tune the nanometer scale morphology of the bulk heterojunction. The full mechanism of efficiency improvement is, however, not completely understood.

A Closer Look into Two-Step Perovskite Conversion with X-ray Scattering.

Recently, hybrid perovskites have gathered much interest as alternative materials for the fabrication of highly efficient and cost-competitive solar cells; however, many questions regarding perovskite crystal formation and deposition methods remain. Here we have applied a two-step protocol where a crystalline PbI2 precursor film is converted to MAPbI3-xClx perovskite upon immersion in a mixed solution of methylammonium iodide and methylammonium chloride. We have investigated both films with grazing incidence small-angle X-ray scattering to probe the inner film morphology.

A direct evidence of morphological degradation on a nanometer scale in polymer solar cells.

In situ measurement of a polymer solar cell using micro grazing incidence small angle X-ray scattering (μGISAXS) and current-voltage tracking is demonstrated. While measuring electric characteristics under illumination, morphological changes are probed by μGISAXS. The X-ray beam (green) impinges on the photo active layer with a shallow angle and scatters on a 2d detector.