A compact polymer–inorganic hybrid gas barrier nanolayer for flexible organic light-emitting diode displays

Atomic layer infiltration technology allows the formation of a nanometer-thick polymer-inorganic hybrid barrier layer in polymer material for flexible organic light-emitting diode(OLED)displays.In this study,according to transmission electron microscopy and secondary-ion mass spectrometry analysis results under various process conditions,a compact polymer-inorganic hybrid nanolayer was successfully formed in a polymer and good barrier performance was revealed with a low water vapor transmission rate under optimal process conditions.Additionally,through gas chromatography-mass spectrometry measurements after ultra-violet radiation testing,polymer out-gassing decreased compared to bare polymers.Based on barrier properties,the polymer with a polymer-inorganic hybrid barrier nanolayer was applied to a flexible OLED display as a substrate.During storage tests and folding tests,the flexible OLED display exhibits good reliability and better flexibility compared to those with an inorganic barrier layer.These results confirm that the polymer-inorganic hybrid nanolayer is suitable for barrier layer formation in flexible OLED displays.

Black Photoresist for Patterning Pixel Define Layer of Organic Light Emitting Diode with Polyimide as Thermal Stabilizer

In order to improve the visibility for outside use of organic light emitting diodes (OLEDs), the polarized film and black matrix pattern have been used in the small and medium sized OLEDs;however, these cause problem of reducing the emission efficiency of OLED. Changing the color of pixel define layer (PDL) from brown to black is an important point for improving the efficiency and visibility of OLEDs. In this work we studied the photoresist material containing black pigment and the photolithographic process for patterning of black PDL on OLEDs. The black PDL patterns made with our synthesized polyimides as thermal stabilizer were found to give high thermal stability over 300°C.

Fabrication of practical deformable displays:advances and challenges

Display form factors such as size and shape have been conventionally determined in consideration of usability and portability.The recent trends requiring wearability and convergence of various smart devices demand innovations in display form factors to realize deformability and large screens.Expandable displays that are foldable,multi-foldable,slidable,or rollable have been commercialized or on the edge of product launches.Beyond such two-dimensional(2D)expansion of displays,efforts have been made to develop three dimensional(3D)free-form displays that can be stretched and crumpled for use in realistic tactile sensation,artificial skin for robots,and on-skin or implantable displays.This review article analyzes the current state of the 2D and 3D deformable displays and discusses the technological challenges to be achieved for industrial commercialization.

六方-BN对非晶前驱体制备不含添加剂的Si_3N_4/SiC复合材料相变的影响(英文)

Si3N4/SiC纳米复合材料由于具有优良的力学和热性能,广泛应用于涡轮发动机、热交换器和其他复杂情况中。然而,不添加添加剂很难制备出Si3N4/SiC复合材料。添加剂在烧结过程形成液相从而促进复合材料的致密化。然而,添加剂的存在降低了复合材料的高温力学性能。通常在不添加添加剂的情况下,采用电场辅助烧结,利用聚合物前体路线制备Si3N4/SiC复合材料。本研究中,在无添加剂、温度1700°C、真空50MPa条件下,热压烧结2h,利用非晶前体路线成功制备了六方-BN致密化的Si3N4/SiC复合材料。聚合物前驱体和BN的作用减少了的SiC含量。并对相变、致密化、微观组织和力学性能进行了讨论。

Elasto-inertial microfluidic separation of microspheres with submicron resolution at high-throughput

Elasto-inertial microfluidic separation offers many advantages including high throughput and separation resolution.Even though the separation efficiency highly depends on precise control of the flow conditions,no concrete guidelines have been reported yet in elasto-inertial microfluidics.Here,we propose a dimensionless analysis for precise estimation of the microsphere behaviors across the interface of Newtonian and viscoelastic fluids.Reynolds number,modified Weissenberg number,and modified elastic number are used to investigate the balance between inertial and elastic lift forces.Based on the findings,we introduce a new dimensionless number defined as the width of the Newtonian fluid stream divided by microsphere diameter.The proposed dimensionless analysis allows us to predict whether the microspheres migrate across the co-flow interface.The theoretical estimation is found to be in good agreement with the experimental results using 2.1-and 3.2-μm-diameter polystyrene microspheres in a co-flow of water and polyethylene oxide solution.Based on the theoretical estimation,we also realize submicron separation of the microspheres with 2.1 and 2.5μm in diameter at high throughput,high purity(>95%),and high recovery rate(>97%).The applicability of the proposed method was validated by separation of platelets from similar-sized Escherichia coli(E.coli).

Metadynamics sampling in atomic environment space for collecting training data for machine learning potentials

The universal mathematical form of machine-learning potentials(MLPs)shifts the core of development of interatomic potentials to collecting proper training data.Ideally,the training set should encompass diverse local atomic environments but conventional approaches are prone to sampling similar configurations repeatedly,mainly due to the Boltzmann statistics.As such,practitioners handpick a large pool of distinct configurations manually,stretching the development period significantly.To overcome this hurdle,methods are being proposed that automatically generate training data.Herein,we suggest a sampling method optimized for gathering diverse yet relevant configurations semi-automatically.This is achieved by applying the metadynamics with the descriptor for the local atomic environment as a collective variable.As a result,the simulation is automatically steered toward unvisited local environment space such that each atom experiences diverse chemical environments without redundancy.We apply the proposed metadynamics sampling to H:Pt(111),GeTe,and Si systems.Throughout these examples,a small number of metadynamics trajectories can provide reference structures necessary for training high-fidelity MLPs.By proposing a semiautomatic sampling method tuned for MLPs,the present work paves the way to wider applications of MLPs to many challenging applications.