Properties Study of SILAR Deposited Cobalt Selenide Thin Films

Thin films are attractive materials to be used in laser, solar cells, sensors, phosphors, light emitting diodes, IR windows and flat panel displays. Several deposition methods have been employed to deposit thin films as reported by many researchers. In this report, the cobalt selenide thin films have been deposited onto microscope glass slide via successive ionic layer adsorption and reaction method. This deposition method is a simple method owing to the inexpensive technique and can produce films at a low bath temperature. All the samples were investigated by using XRD, FESEM and UV-visible spectrophotometer. The XRD pattern confirmed that cubic phase cobalt selenide thin films. The FESEM image exhibited that the obtained sample is dense, uniform, and smooth surface. Keywords: XRD, FESEM, Thin films, Cobalt selenide, SILAR technique, Semiconductor, Band gap.

Investigation of Enhanced Ambient Contrast Ratio in Novel Micro/Mini-LED Displays

In recent years, ambient contrast ratio (ACR) has become very critical for advanced outdoor displays, including transparent displays, portable displays, and so on. In this work, the ACR of typical flat panel displays was introduced, while LED-based displays showed distinctive advantages. Micro-LED displays with a different pitch of 10 μm, 15 μm, 30 μm, and 60 μm were fabricated and characterized. Various mini-LED and micro-LED panels were systematically investigated in the aspect of brightness, reflection phenomenon, and ACR to reveal their enormous potential for outdoor applications. Through a series of experiments and comparisons, three methods were proposed to further improve the ACR of LED-based panels, including optical method, antireflection coating, and structure optimization.

High-Speed Column Driver IC Having Buffer Amplifier with Embedded Isolation Switch and Compact Adaptive Biasing for Flat-Panel Displays

A high-speed column driver IC with an area-efficient high-slew-rate buffer amplifier is proposed for use in a large-sized, high-resolution TFT-LCD panel application. In the proposed architecture, explicit isolation switches have been embedded into the buffer amplifier resulting in a fast settling response. The amplifier also has a structure that adjusts the tail current of the input stage using a very compact adaptive biasing. The proposed column driver IC, having the proposed buffer amplifier for driving a 55-inch 4K ultra-high-definition (UHD) TV panel, was fabricated in a 0.18-μm 1.8-V low-voltage, 1.2-μm 9-V medium-voltage, and 1.6-μm 18-V high-voltage CMOS process. The performance evaluation results indicated that 90% and 99.9% falling settling times were improved from 1.947 µs to 0.710 µs (63.5% improvement) and 4.131 µs to 2.406 µs (41.7% improvement), respectively. They also indicated that the layout size of the proposed buffer amplifier was reduced from 5580 μm2 to 4402 μm2 (21.1% reduction).

Enhancement of Photodetective Properties on Multilayered MoS2 Thin Film Transistors via Self-Assembled Poly-L-Lysine Treatment and Their Potential Application in Optical Sensors

Photodetectors and display backplane transistors based on molybdenum disulfide (MoS2) have been regarded as promising topics. However, most studies have focused on the improvement in the performances of the MoS2 photodetector itself or emerging applications. In this study, to suggest a better insight into the photodetector performances of MoS2 thin film transistors (TFTs), as photosensors for possible integrated system, we performed a comparative study on the photoresponse of MoS2 and hydrogenated amorphous silicon (a-Si:H) TFTs. As a result, in the various wavelengths and optical power ranges, MoS2 TFTs exhibit 2~4 orders larger photo responsivities and detectivities. The overall quantitative comparison of photoresponse in single device and inverters confirms a much better performance by the MoS2 photodetectors. Furthermore, as a strategy to improve the field effect mobility and photoresponse of the MoS2 TFTs, molecular doping via poly-L-lysine (PLL) treatment was applied to the MoS2 TFTs. Transfer and output characteristics of the MoS2 TFTs clearly show improved photocurrent generation under a wide range of illuminations (740~365 nm). These results provide useful insights for considering MoS2 as a next-generation photodetector in flat panel displays and makes it more attractive due to the fact of its potential as a high-performance photodetector enabled by a novel doping technique.

Computational study of comprehensive methods of initiating phase separation within metastable regions and obtaining some notable patterns in unstable region

Binary phase polymer solution is interesting in that they expresses double-well local energy behavior, which means phase separation is preferred when condition is right. It is a feature that has been used to fabricate functional polymeric materials such as PDLC films for electro-optical devices (e.g. flat-panel displays and switchable windows). A uniformly mixed solution may be in one of three state: unstable, stable, or metastable. If the solution is unstable, then phase separation is spontaneous and proceeds by spinodal decomposition. If the solution is metastable, then the solution must overcome certain activation barrier for phase separation to proceed spontaneously. The activation barrier is usually the thermal noise or the fluctuation created by some external influence. This mechanism is called nucleation-and-growth. Manipulating morphology of phase separation has been of some great research interest because of its practical use. While spinodal decomposition has been well-studied, there are several other methods to further control morphology. For this thesis, the following methods are considered: double quench, anisotropic quenching with varying temperature or polymerization, surface-directed wetting, and concentration gradient. The methods are carried out within metastable or unstable regions or both. To numerically model, Cahn-Hilliard theory and FloryHuggins’ theory are used. This thesis is to also demonstrate that, present numerical method is very efficient and can work on complex geometry.

Computational study of comprehensive methods of initiating phase separation within metastable regions and obtaining some notable patterns in unstable region

Binary phase polymer solution is interesting in that they expresses double-well local energy behavior, which means phase separation is preferred when condition is right. It is a feature that has been used to fabricate functional polymeric materials such as PDLC films for electro-optical devices (e.g. flat-panel displays and switchable windows). A uniformly mixed solution may be in one of three state: unstable, stable, or metastable. If the solution is unstable, then phase separation is spontaneous and proceeds by spinodal decomposition. If the solution is metastable, then the solution must overcome certain activation barrier for phase separation to proceed spontaneously. The activation barrier is usually the thermal noise or the fluctuation created by some external influence. This mechanism is called nucleation-and-growth. Manipulating morphology of phase separation has been of some great research interest because of its practical use. While spinodal decomposition has been well-studied, there are several other methods to further control morphology. For this thesis, the following methods are considered: double quench, anisotropic quenching with varying temperature or polymerization, surface-directed wetting, and concentration gradient. The methods are carried out within metastable or unstable regions or both. To numerically model, Cahn-Hilliard theory and FloryHuggins’ theory are used. This thesis is to also demonstrate that, present numerical method is very efficient and can work on complex geometry.

Efficient organic manganese (II) bromide green-light-emitting diodes enabled by manipulating hole and electron transport layer

Lead-free, non-toxic transition metal-based phosphorescent organic–inorganic hybrid (OIH) compounds are promising for next-generation flat-panel displays and solid-state light-emitting devices. In the present study, we fabricate highly efficient phosphorescent green-light-emitting diodes...

High-Efficiency Red Perovskite Light-emitting Diodes Based on Collaborative Optimization of Emission Layer and Transport Layers

Metal halide perovskite light-emitting diodes (PeLEDs) is a new type of electroluminescent device with wide application in flat-panel displays and solid-state lighting. The charge recombination at the electrode interfaces and...