Sidewall emission of a micro-scale light emitting diode (micro-LED) improves the light extraction efficiency, but it causes mismatched angular distributions between AlGaInP-based red micro-LED and ...InGaN-based blue/green counterparts due to material difference. As a result, color shift of RGB micro-LED displays may become visually noticeable. To address this issue, we first analyze the angular distributions of RGB micro-LEDs and obtain good agreement between simulation and experiment. Next, we propose a device structure with top black matrix and taper angle in micro-LEDs, which greatly suppresses the color shift while keeping a reasonably high light extraction efficiency.
Mitochondrial transcriptional factor A (TFAM) acts as a key regulatory to control mitochondrial DNA (mtDNA); the impact of TFAM and mtDNA in modulating carcinogenesis is controversial. Current study ...aims to define TFAM mediated regulations in head and neck cancer (HNC). Multifaceted analyses in HNC cells genetically manipulated for TFAM were performed. Clinical associations of TFAM and mtDNA encoded Electron Transport Chain (ETC) genes in regulating HNC tumourigenesis were also examined in HNC specimens. At cellular level, TFAM silencing led to an enhanced cell growth, motility and chemoresistance whereas enforced TFAM expression significantly reversed these phenotypic changes. These TFAM mediated cellular changes resulted from (1) metabolic reprogramming by directing metabolism towards aerobic glycolysis, based on the detection of less respiratory capacity in accompany with greater lactate production; and/or (2) enhanced ERK1/2-Akt-mTORC-S6 signalling activity in response to TFAM induced mtDNA perturbance. Clinical impacts of TFAM and mtDNA were further defined in carcinogen-induced mouse tongue cancer and clinical human HNC tissues; as the results showed that TFAM and mtDNA expression were significantly dropped in tumour compared with their normal counterparts and negatively correlated with disease progression. Collectively, our data uncovered a tumour-suppressing role of TFAM and mtDNA in determining HNC oncogenicity and potentially paved the way for development of TFAM/mtDNA based scheme for HNC diagnosis.
We propose a novel optical design to tailor the angular distribution of a micro-LED (µLED) display system and use vehicle display as an example to illustrate the design principles. The display system ...consists of a µLED array with a tailored LED structure, a small formfactor compound parabolic concentrator (CPC) system, and a functional engineered diffusor. It provides high efficiency, high peak brightness, and small formfactor. In the design process, a mix-level optical simulation model, including the angular distribution of polarized emission dipole (dipole emission characteristics), Fabry-Perot cavity effect (wave optics), and light propagation process (ray optics), is established to analyze the angular distribution of µLEDs. Such an optical design process from dipole emission to display radiation pattern can be extended to other µLED display systems for different applications.
Micro-LED (light-emitting diode) is a potentially disruptive display technology, while power consumption is a critical issue for all display devices. In this paper, we develop a physical model to ...evaluate the power consumption of micro-LED displays under different ambient lighting conditions. Both power efficiency and ambient reflectance are investigated in two types of full color display structures: red/green/blue (RGB) micro-LEDs, and blue-LED pumped quantum dots color-conversion. For each type of display with uniform RGB chip size, our simulation results indicate that there exists an optimal LED chip size, which leads to 30–40% power saving. We then extend our model to analyze different RGB chip sizes, and find that with optimized chip sizes an additional 12% average power saving can be achieved over that with uniform chip size.
Color-converted micro-LED displays consist of a mono-color micro-LED array and color conversion materials to achieve full color, while relieving the burden of epitaxial growth of three-color ...micro-LEDs. However, it usually suffers from low efficiency and color crosstalk due to the limited optical density of color conversion materials. With funnel-tube array, the optical efficiency of the color-converted micro-LED display can be improved by ~3X, while the crosstalk is eliminated. After optimization of the tapper angle, the ambient contrast ratio is also improved due to higher light intensity.
We propose a new electrode configuration, called diamond-shape in-plane switching, to lower the operation voltage of polymer-stabilised blue-phase liquid crystal (BPLC) displays (BPLCDs). The ...electrode structure is modified from conventional protruded IPS, where the strip protrusion is changed to diamond shape. By optimising the electrode gap and diamond length, we are able to obtain peak transmittance over 75% at 15 V. It enables single thin-film transistor (TFT) driving, and more importantly, this is based on an industrially proven BPLC material. That means good long-term stability, adequate TFT charging time for high-resolution displays and sub-millisecond response time and acceptable voltage-holding ratio for field sequential displays can be achieved simultaneously. Our device design helps accelerate the emergence of the long-awaited BPLCDs.
Inverse spinel SnFe2O4 as an anode material for lithium-ion batteries (LIBs) suffers from poor cycling stability due to its lower conductivity and excess volume change during charge/discharge ...process. In order to overcome the obstacles, a series of SnFe2O4@reduced graphene oxide (rGO) composites with different amount of Sn(Fe)–C bonds between SnFe2O4 and rGO interface are synthesized through a simple one-pot solvothermal method and subsequent sintering at different temperatures. The composite with higher Sn(Fe)–C bonds content exhibits higher charge/discharge capacities of 1010/1020 mAh g−1 at 0.5 A g−1 for 300 cycles, and a better rate capability of 620 mAh g−1 at 2.0 A g−1. The synergistic effect of larger content of Sn(Fe)–C bonds and the formed flower-like networks between the pulverized SnFe2O4 and the rGO interface during charge/discharge is favor to improve the kinetics of SnFe2O4, because the networks are acted as the transport highway for electronics and lithium-ions. Moreover, the higher content and strong action of Sn(Fe)–C bonds can prevent the SnFe2O4 nanoparticles suffer from excessively volume change and pulverize during cycling. Designing chemically bonded metal oxides with graphene composite could provide a simple way to improve the cycle stability and rate capability of the LIBs.
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•Various amount of Sn(Fe)–C bonds between SnFe2O4 and graphene interface are obtained.•The composite with higher content of Sn(Fe)–C bonds exhibits higher capacities.•Flower like networks formed on SFG interface act as transport highway for Li+.•The anode shows high stable capacity of 1020 mAh g−1 at 0.5 A g−1 for 300 cycles.
Polymer-network stabilized blue phase liquid crystal (BPLC) has been studied for decade; however, mechanism of hysteresis is not fully understood. In this report, based on the interaction between ...polymer-network and blue phase liquid crystal, mechanism of hysteresis was proposed. Results and discussion were confirmed by experimental data and literature reports. Mechanism of hysteresis is governed by three dominated factors, primary factor is relaxation ability of BPLC, secondary is steric hindrance of polymer network and tertiary is anchoring force between BPLC and polymer network. Although experimental results showed trade off in eliminate hysteresis, an effective approach of dual frequency effect was applied and hysteresis was significantly reduced from 4.44% to 0.01%.
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We comprehensively investigated the concentration effect of dispersed single-walled carbon nanotubes (SWCNTs) in polymer films for being a saturable absorber (SA) to stabilize the mode locking ...performance of the erbium-doped fiber laser (EDFL) pulse through the diagnosis of its nonlinear properties of SA. The measured modulation depth was from 1 to 4.5% as the thickness increased 18 to 265 microm. The full-width half-maximum (FWHM) of the stable mode-locked EDFL (MLEDFL) pulse decreased from 3.43 to 2.02 ps as the concentrations of SWCNTs SA increased 0.125 to 0.5 wt%. At constant concentration of 0.125 wt%, the similar pulse shortening effect of the MLEDFL was also observed when the FWHM decreased from 3.43 to 1.85 ps as the thickness of SWCNTs SA increased 8 to 100 microm. With an erbium-doped fiber length of 80 cm, the shortest pulse width of 1.85 ps were achieved at 1.56 microm with a repetition rate of 11.1 MHz and 0.2 mW of the output power under an output coupling ratio of 5%. An in-depth study on the stable mode-locked pulse formation employing SWCNTs SA, it is possible to fabricate the SWCNT films for use in high performance MLEDFL and utilization of many other low-cost nanodevices.
Color-converted micro-light-emitting diode (micro-LED) displays with wide color gamut, high ambient contrast ratio, and fast response time are emerging as a potentially disruptive technology. ...However, due to limited optical density and thickness of the color-conversion film, the blue light leakage and low color-conversion efficiency still hinder their widespread applications. In this paper, we demonstrate a patterned cholesteric liquid crystal (CLC) polymer film with two special optical functionalities. On the green and red sub-pixels, the corresponding planar CLC texture acts as a distributed Bragg reflector for the blue light, which in turn improves the color conversion efficiency and expands the color gamut. On the blue sub-pixels, the corresponding focal-conic CLC texture acts as light scattering medium, which helps to reduce the angular color shift. Further analysis reveals that the patterned CLC film can alleviate the crosstalk between green and blue color filters. Therefore, compared to the display system without such a CLC film, our proposed device structure increases the color conversion efficiency by 143% (at ~90% Rec. 2020) and reduces average angular color shift Δu'v' from 0.03 to 0.018 at the viewing angle with the most severe color shift. Such a patterned CLC film is applicable to all kinds of color-conversion display systems, including organic and inorganic phosphors.
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