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In an effort to understand recent results showing differences between the power conversion efficiencies of lead halide (CH3NH3PbI3−xClx) solar cells on glass versus flexible substrates, this study investigates the influence that substrate and processing methods have on morphological and crystallographic development. Using our in situ slot-die micro roll-to-roll coater setup, we measured small and wide angle X-ray scattering in grazing incidence while the material dried, enabling us to follow the crystallization from just after the deposition and up to 25 minutes later. The data showed differing crystallographic developments between the substrates, especially seen through the behaviour of a crystalline precursor which survived longer on the flexible substrates than on glass. Additionally, the common degradation product PbI2 was absent on the thickest flexible substrate. This leads us to conjecture that the flexible substrates absorb part of the solvent, thereby delaying evaporation and changing the solvent environment around the perovskite. As a further test, we produced solar cells with the same substrates and confirmed that the ones made on flexible substrates performed worse than those made on glass, but that when including an ITO layer in the stack it seemed to act as a buffer, whereby the solar cell performance was improved. [ABSTRACT FROM AUTHOR]

Poly(L-lactide) in its L-form has promising mechanical properties. Being a semicrystalline polymer, it can be subjected to strain-induced crystallization at temperatures above Tg and can thereby become oriented. Following a simultaneous (SIM) biaxial strain process or a sequential (SEQ) biaxial strain process, the mechanical properties of biaxially strained tubes can be further improved. This study investigated these properties in relation to their morphology and crystal orientation. Both processes yield the samemechanical strength and modulus, yet exhibit different crystal orientation. Through furtherwide angle X-ray scattering analysis it was found that the SEQ biaxial strain yields larger interplanar spacing and distorted crystals and looser packing of chains. However, this does not influence the mechanical properties negatively. A loss of orientation in SEQ biaxially strained samples at high degrees of strain was detected, but was not seen for SIM biaxial strain and did not correlate with mechanical performance in either case. However, post-annealing reduced the orientation to the same level in both cases, andthemodulusandstrengthdecreased forboth SIMandSEQbiaxial strain. It is therefore concluded thatmechanicalproperties after biaxial strain are related to strain-induced amorphous orientation and the packing of crystals, rather than strain-induced crystallinity. [ABSTRACT FROM AUTHOR]

The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V2O5∙(H2O)n/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(V)oxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE) for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker. [ABSTRACT FROM AUTHOR]

A correction to the article "Semi-metallic polymers" that was published online in a previous issue is presented.

Fiber-reinforced composites deliver lightweight but strong structures that are crucial in applications ranging from aerospace to the automotive industry. The advent of freeform injection molding has made the manufacturing of complex fiber-reinforced composites with full design freedom possible. Prediction of the mechanical properties, dictated by the local microfiber orientation, is essential for the performance characterization of fiber-reinforced composites. However, with conventional microtomography, the required microscale spatial resolution and the macroscopic field of view for full-size fiber-reinforced composite pieces cannot be effectively decoupled. X-ray scattering tensor tomography enables non-destructive macroscopic mapping of the local microfiber orientation as well as their degree of alignment. Recent advancements in X-ray optics have significantly increased the acquisition speed, making the tensor tomography attractive for industrial applications. Nonetheless, integration of the tensor tomography within production lines requires a flexible and robust implementation. In this work, we demonstrate the potential of X-ray scattering tensor tomography for industrial applications by characterizing the microstructure of a centimeter-sized industrially relevant freeform injection molding fiber-reinforced composite sample. We also show that the tensor tomography is compatible with robotic arms, which can position and orient objects in three dimensions with high flexibility and therefore are ideal sample manipulators for the tensor tomography in industrial settings. The results obtained with the robotic arm are compared to those obtained with the state-of-the-art 2-axis sample manipulation scheme. The retrieved information is highly consistent and shows agreement also with structure tensor analyses of conventional microtomography data taken at selected regions of the sample for additional validation. [ABSTRACT FROM AUTHOR]

Abstract: Double slot-die coating using aqueous inks was employed for the simultaneous coating of the active layer and the hole transport layer (HTL) in fully roll-to-roll (R2R) processed polymer solar cells. The double layer film was coated directly onto an electron transport layer (ETL) comprising doped zinc oxide that was processed by single slot-die coating from water. The active layer comprised poly-3-hexylthiophene:Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) as a dispersion of nanoparticles with a radius of 46nm in water characterized using small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The HTL was a dispersion of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) in water. The films were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS) as chemical probe and X-ray reflectometry as physical probe, confirming the identity of the layered structure. The devices were completed with a back electrode of either Cu tape or evaporated Ag. Under standard solar spectrum irradiation (AM1.5G), current–voltage characterization (J–V) yielded an open-circuit voltage (V oc ), short-circuit current (J sc ), fill factor (FF), and power conversion efficiency (PCE) of 0.24V, 0.5mAcm−2, 25%, and 0.03%, respectively, for the best double slot-die coated cell. A single slot-die coated cell using the same aqueous inks and device architecture yielded a V oc , J sc , FF, and PCE of 0.45V, 1.95mAcm−2, 33.1%, and 0.29%, respectively. [Copyright &y& Elsevier]