Hybrid organic inorganic perovskites are a promising highly efficient photovoltaic material that can be solution processed at low temperatures enabling an inexpensive solution to rising renewable energy demands with high-volume, scalable manufacturing of solar cells. Small scale perovskite devices are successful using spin coating; however, this needs to translate to larger scale deposition systems such as roll-to-roll slot die printing. Understanding the crystallization and morphology dependence of these materials is essential to enabling slot-die coated perovskite films on scalable systems and transitioning this technology to the market. In order to model crystallization rates of printed layers, we used in-situ optical and photoluminescence microscopy during printing of perovksite films to determine crystal growth rates and evaluate perovskite conversion. Printing parameters were manipulated through variation of temperature, atmospheric conditions, ink recipes, and substrate surface energy generating a model to achieve desired grain size and morphology of the perovskite layer across an array of relevant potential perovskite photovoltaic device stacks. Following classical models, we determined the necessary parameters to translate these fundamentals to perovskite crystallization and grain growth. We further explored the conversion and degradation of the perovskite phases through the printing process, which plays a significant role in device performance, through in situ photoluminescence microscopy, as well as verification through X-ray diffraction. Verification of the observed grain sizes and morphology was also done through scanning electron microscopy, to ensure optical measurements and analysis were accurate. With efficiencies of perovskites approaching current industry standards of silicon, perovskites are increasingly becoming the clear answer to solar industry demands. This research is essential in enabling scalable methods with the potential to revolutionize the solar industry with large scale fully printable devices.

Maintenance of neutral buoyancy is a challenge to all fishes. In shallow water, this is typically achieved through the use of a swim bladder, though a more favorable mechanism for deep-sea species is through a reduction in skeletal structure. Extreme environmental conditions—low temperature, high pressure, lack of light, limited food availability, and varying oxygen concentrations—exert evolutionary pressures on organisms that inhabit the deep sea. The family Liparidae (snailfishes) span the largest depth range of any marine fishes. Hadal snailfishes, the deepest-living fishes, reside as deep as ~8,200 meters. With the elimination of swim bladders, a reduction in skeletal structure has become the mechanism by which this family achieves the buoyancy needed to hunt in the water column. We used micro-computed tomography (micro-CT) scanning to study bone density across the full bathymetric range of the Liparidae with representatives across the family tree. Of these specimens, five bones were measured for density: the lower jaw, for purposes of feeding mechanics; the third vertebrae, as a control; the first left pelvic pterygiophore for studying the suction disk; the hypural plate, to study swimming and movement trends, and the sagittal otoliths. Phylogenetic analyses revealed a decrease in bone density with increasing depth. The degree of change in density with depth differed among the structures measured, implying evolutionary effects on the function and performance of bone structures in the deep sea.

Skeletal reduction is a common feature among deep-sea fishes that have diversified from shallow-water relatives, such as snailfishes. These skeletal reductions may be an adaptation to environmental conditions of high pressures, low temperatures, declining luminosity and limited food availability. Snailfishes (family Liparidae) are found across a large bathymetric range (0 – >8,000 m), with intertidal ancestors giving rise to a large clade of deep-sea species. We used microcomputed tomography (micro-CT) to estimate average bone mineral density and examine jaw, pectoral girdle, and neurocranium morphology. Our results suggest at least three mechanisms of skeletal reduction: (1) reduction of bone size, (2) reduction of bone density, and (3) loss of skeletal elements. First, using phylogenetic generalized least squares (PGLS) analysis, we found that the change in cranial dimensions with depth was not uniform. While the size of the maxilla, dentary, and pectoral girdle decreased with greater depth, length of the upper premaxilla and the neurocranium did not vary with collection depth. Second, average density of the lower jaw decreased with increasing depth. Lastly, the ventral suction disc has been lost multiple times within the deep-sea lineage. While all three methods are seen in snailfishes, other groups may use some or all of these mechanisms to different extents. Some mechanisms of skeletal reduction may be more advantageous than others. The extent to which a structure is retained in deep-dwelling fishes may indicate its functional importance. Variable skeletal reduction in the family Liparidae provides insights into the physiological adaptations that allow fishes to survive in deep-water environments. We conclude that some skeletal elements are maintained at the expense of others as fishes balance the functional demands of life in the deep sea.