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The emergence of near‐eye displays for an extended reality (XR) has promoted the development of high‐resolution electroluminescence quantum dot (EL‐QD) devices. Direct photo‐lithography using photosensitive moieties is an effective technique for producing micrometer‐sized patterns of colloidal quantum dots. Here, we fabricated red, green, and blue quantum dot patterns with a resolution of >4,500 pixels per inch using an azide‐based photo‐crosslinking method, which is a simple and applicable to a versatile patterning or integrating process. The effect of QD ligands and solvents on the electroluminescence characteristics and pattern fidelity of QD films during the patterning process was studied. [ABSTRACT FROM AUTHOR]

Abstract: Two series of brush polyimides (PIs) with various lengths of the bristles were studied as thin films using atomic force microscopy, optical retardation and linearly polarized infrared spectroscopy before and after rubbing, and their nematic liquid crystal (LC) aligning abilities were investigated: poly(p-phenylene 3,6-bis(4-(n-alkyloxy)phenyloxy)pyromellitimide)s (Cn-PMDA-PDA PIs: n =4, 6, 7 and 8) and poly(4,4′-methylenyldiphenylene 3,6-bis(4-(n-alkyloxy)phenyloxy)pyromellitimide)s (Cm-PMDA-MDA PIs: m =1, 4, 8 and 12). For all the PI films, the rubbing process was found to create microgrooves in the films along the rubbing direction, and to orient the polymer main chains and the n-alkyl bristle end groups along the rubbing direction, but to orient the phenyloxy bristle units perpendicular to the rubbing direction. The LC molecules on the rubbed film surfaces of Cn-PMDA-PDA PIs with n =4, 6 and 7 were found to be aligned perpendicular to the rubbing direction. In contrast, rubbed films of Cn-PMDA-PDA PIs (n =8) and Cm-PMDA-MDA PIs (m =1, 4, 8 and 12) induced LC alignment parallel to the rubbing direction. These results collectively lead a conclusion that LC alignment on the rubbed PI film is determined by a play-off between the directionally anisotropic interactions the LC molecules with all possible factors associated at the film surface. [Copyright &y& Elsevier]

Abstract: The molecular orientations and surface morphologies of rubbed films formed from atactic polystyrene (PS) samples with various molecular weights were investigated in detail. Previously unknown surface topography features were newly discovered in rubbed films, depending on molecular weights: submicroscale groove-like meandering structures composed of fine-grooves like pebbles in 10nm are present, oriented perpendicular to the rubbing direction. The vinyl main chains, however, were preferentially oriented along the rubbing direction and the planes of the phenyl side groups were preferentially oriented perpendicular to the rubbing direction with para-directions that were positioned nearly normal to the film plane. Nematic liquid crystal (LC) molecules were found to always align on the rubbed PS surfaces along the orientation direction of the submicroscale grooves generated by rubbing. [Copyright &y& Elsevier]

Poly[bis(9H-carbazole-9-ethyl)dipropargylmalonate] (PCzDPM) is a novel pi-conjugated polymer bearing carbazole moieties that has been synthesized by polymerization of bis(9H-carbazole-9-ethyl)dipropargylmalonate with the aid of molybdenum chloride solution as the catalyst. This polymer is thermally stable up to 255 degrees C under a nitrogen atmosphere and 230 degrees C in air ambient; its glass-transition temperature is 147 or 128 degrees C, depending on the polymer chain conformation (helical or planar structure). The charge-transport characteristics of PCzDPM in nanometer-scaled thin films were studied as a function of temperature and film thickness. PCzDPM films with a thickness of 15-30 nm were found to exhibit very stable dynamic random access memory (DRAM) characteristics without polarity. Furthermore, the polymer films retain DRAM characteristics up to 180 degrees C. The ON-state current is dominated by Ohmic conduction, and the OFF-state current appears to undergo a transition from Ohmic to space-charge-limited conduction with a shallow-trap distribution. The ON/OFF switching of the devices is mainly governed by filament formation. The filament formation mechanism for the switching process is supported by the metallic properties of the PCzDPM film, which result in the temperature dependence of the ON-state current. In addition, the structure of this pi-conjugated polymer was found to vary with its thermal history; this change in structure can affect filament formation in the polymer film.