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Rapid Spray Plasma Processing (RSPP) is a high throughput, scalable, and open-air route toward manufacturing perovskite solar modules. The plasma exposure is dosed such that the perovskite precursor solution is cured in milliseconds using a combination of rapid heating, reactive species, and UV photons. We implemented in situ wide angle X-ray scattering (WAXS) to characterize the crystal growth in multiple cation, mixed halide perovskite thin films—Csx(MAzFA1−z)1−xPb(Br0.17I0.83)3 for 0.05 ≤ x ≤ 0.25—fabricated in open air. The use of synchrotron radiation and high detector speeds resolved the formation and dissolution of a transient intermediate crystalline phase during the tens of milliseconds when the perovskite crystallized. Increasing the mole fraction of cesium and methylammonium resulted in a decrease in the intermediate phase and an increase in the average grain diameter. Increasing the cesium fraction suppressed phase segregation, as observed in photoluminescence. Calculations showed the refractive index decreased and the extinction coefficient increased with cesium fraction. Based on the rapid crystallization kinetics, RSPP perovskite films exhibit residual stress values >5× lower than spin coated films. Understanding the kinetics of perovskite formation enables the design of perovskite films with improved thermomechanical and operational stability. [ABSTRACT FROM AUTHOR]

We report on submicron organosilicate barrier films produced rapidly in air by a scalable spray plasma process that improves both the stability and efficiency of perovskite solar cells. The plasma is at sufficiently low temperature to prevent damage to the underlying layers. Oxidizing species and heat from the plasma improve device performance by enhancing both interfacial contact and the conductivity of the hole transporting layer. The thickness of the barrier films is tunable and transparent over the entire visible spectrum. The morphology and density of the barrier are shown to improve with the addition of a fluorine-based precursor. Devices with submicron coatings exhibited significant improvements in stability, maintaining 92% of their initial power conversion efficiencies after more than 3000 h in dry heat (85 °C, 25% RH) while also being resistant to degradation under simulated operational conditions of continuous exposure to light, heat, and moisture. X-ray diffraction measurements performed while heating showed the barrier film dramatically slows the formation of PbI2. The barrier films also are compatible with flexible devices, exhibiting no signs of cracking or delamination after 10 000 bending cycles on a 127 μm substrate with a bending radius of 1 cm. [ABSTRACT FROM AUTHOR]

The orientation and deformation mechanisms in the filler and in the matrix of filled natural rubber were studied by ultra small-angle X-ray scattering (USAXS) and wide-angle X-ray diffraction (WAXD) performed on rubber samples stretched in situ. Using model fillers that give a signal in the wide and in the small-angle region allowed us to correlate the models developed to interpret the USAXS data with the information obtained from the WAXD data. Due to the simple geometries of aragonite and nano-sized aluminum oxide, which served as model fillers, an analytical description using form factors can well represent the experimental two-dimensional USAXS data of oriented stretched samples. Besides the study of the filler structure, an attempt was made to resolve the local strain in the matrix. We took advantage of the peculiar property of natural rubber, that is, strain-induced crystallization, to unravel the matrix strain by measuring the degree of crystallinity. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 [ABSTRACT FROM AUTHOR]

The time-dependence of strain-induced crystallizationin cross-linkednatural rubber was studied using synchrotron wide-angle X-ray diffraction(WAXD) with an unprecedented time resolution in the ms range. In-situdynamic mechanical tests and tensile impact tests were carried out.In tensile impact tests, consisting of a strain step within less than10 ms, it was found that roughly half of the crystallization processwas complete within less than 5 ms, provided the strain is large enough.Afterward, crystallization proceeded on a time scale of a few seconds.This implies that under dynamic loading at frequencies which are typicallyencountered in the application of rubbers, the degree of crystallinityis considerably lower than under equilibrium conditions. This wasdirectly confirmed by in situ dynamic cyclic experiments at a frequencyof approximately 1 Hz. Since crystallization is a major factor contributingto the outstanding mechanical properties of natural rubber, thesefindings can aid in the interpretation and prediction of the frequency-dependenceof mechanical properties. [ABSTRACT FROM AUTHOR]