An organic thin film includes an organic solid crystal material and has mutually orthogonal refractive indices, n.sub.x, n.sub.y, and n.sub.z each having a value at 589 nm of between approximately 1.5 and approximately 2.6, where n.sub.xn.sub.yn.sub.z. The organic thin film may be birefringent, and may be configured as a single layer thin film, or plural organic thin films may be stacked to form a multilayer that may be incorporated into an optical element, such as a reflective polarizer.

An organic thin film includes an organic solid crystal material and has mutually orthogonal refractive indices, n.sub.x, n.sub.y, n.sub.z, each having a value at 589 nm of between 1.5 and 2.6, with n.sub.xy<n.sub.xz<n.sub.yz, where the organic solid crystal material includes an organic molecule selected from 1,2,3-trichlorobenzene, 1,2-diphenylethyne, phenazine, terphenyl, 1,2-bis(4-(methylthio)phenyl)ethyne, and anthracene. The organic thin film may be birefringent and may be configured as a single layer thin film, or plural organic thin films may be stacked to form a multilayer that may be incorporated into an optical element, such as a reflective polarizer.

An organic thin film includes an organic solid crystal material and has mutually orthogonal refractive indices, n.sub.x, n.sub.y, n.sub.z, each having a value at 589 nm of between 1.5 and 2.6, with n.sub.xy<n.sub.xz<n.sub.yz, where the organic solid crystal material includes an organic molecule selected from 1,2,3-trichlorobenzene, 1,2-diphenylethyne, phenazine, terphenyl, 1,2-bis(4-(methylthio)phenyl)ethyne, and anthracene. The organic thin film may be birefringent and may be configured as a single layer thin film, or plural organic thin films may be stacked to form a multilayer that may be incorporated into an optical element, such as a reflective polarizer.

A method for screening a target compound for polymorphic forms is provided. The method comprises providing a library of mixed-crystal seeds, each mixed-crystal seed consisting essentially of the target compound and at least one structural analog that is structurally analogous to the target compound; and for each mixed-crystal seed: introducing the mixed-crystal seed into a crystallization medium comprising the target compound, under conditions suitable for crystallization of the target compound; monitoring the formation of crystals of the target compound; and when formed, characterizing the crystals of the target compound.

A method for screening a target compound for polymorphic forms is provided. The method comprises providing a library of mixed-crystal seeds, each mixed-crystal seed consisting essentially of the target compound and at least one structural analog that is structurally analogous to the target compound; and for each mixed-crystal seed: introducing the mixed-crystal seed into a crystallization medium comprising the target compound, under conditions suitable for crystallization of the target compound; monitoring the formation of crystals of the target compound; and when formed, characterizing the crystals of the target compound.

A method of processing chitin includes dispersing nanocrystalline and amorphous chitin within a solvent system thereby to form a mixture, wherein a solid to solvent ratio in the mixture is no more than 7% wt, the solvent system comprising: a first component comprising: at least one ionic liquid; and at least one inorganic base; and a second component comprising water, wherein the first component comprises no more than 10% by volume of the solvent system; the method further comprising: mechanically agitating and/or boiling the mixture; concentrating the mixture thereby to produce an increased solid to solvent system ratio; rapidly dispersing the concentrated mixture in a cold bath of water and/or water-miscible solvent; and decontaminating and collecting substantially preserved and newly crystallized chitin. Other methods, as well as solvent systems for use in same, are provided.

The present application discloses a perovskite layer, a method for preparing a perovskite layer, a perovskite-layer solar cell and a perovskite-layer-solar-cell assembly, which relates to the technical field of photovoltaics, and is used to prepare a perovskite layer that can completely cover the substrate and has few defects. The method for preparing a perovskite layer includes: providing a substrate; forming perovskite seed crystals on the substrate; soaking the perovskite seed crystals into a perovskite solution; by the effect of the perovskite seed crystals, the perovskite seed crystals growing into a perovskite thin film; and performing annealing treatment to the perovskite thin film, to form the perovskite layer. The perovskite layer and the preparing method thereof according to the present application are used for the fabrication of a solar cell.

A two-step process is provided for forming large photonic single crystals of about 0.1 millimeter and greater via DNA coated colloidal particles. The two-step process generally include decoupling the nucleation and growth steps. In particular, DNA colloidal particles are partitioned in nanoliter droplets formed in a water in oil emulsion using microfluidics. Once a crystal nucleates within a droplet, depletion of particles occurs as the crystal grows inhibit formation of more crystals within the droplet. A small number of droplets containing these seed crystals are then mixed with droplets containing weak DNA coated colloidal particles. The emulsion is then broken and heated at a temperature effective to cause dissociation of the weak particles while the seeds remain stable. The system is further cooled at a temperature effective that the particles stably adhere to the seed crystals resulting in growth while inhibiting nucleation of new crystals.

A two-step process is provided for forming large photonic single crystals of about 0.1 millimeter and greater via DNA coated colloidal particles. The two-step process generally include decoupling the nucleation and growth steps. In particular, DNA colloidal particles are partitioned in nanoliter droplets formed in a water in oil emulsion using microfluidics. Once a crystal nucleates within a droplet, depletion of particles occurs as the crystal grows inhibit formation of more crystals within the droplet. A small number of droplets containing these seed crystals are then mixed with droplets containing weak DNA coated colloidal particles. The emulsion is then broken and heated at a temperature effective to cause dissociation of the weak particles while the seeds remain stable. The system is further cooled at a temperature effective that the particles stably adhere to the seed crystals resulting in growth while inhibiting nucleation of new crystals.