We have recently developed screens made of nanomaterial-coated translucent sheets. In these screens, 2D picture images projected on the screen can be transformed automatically into 3D images with stereoscopic backgrounds. The 2D-to-3D transformation is considered to be based on the analogous mechanism that we feel the depth when we see human skin. One of our typical imaging screens consists of three layers made of an aluminum-deposited sheet and two translucent sheets which are coated with titanium dioxide nanoparticles. In this present work, these translucent sheets have been intensively characterized with respect to their optical properties using a CCBTDF instrument. The CCBTDF measurement suggest that the blue light with the short wavelength is scattered on the surface of the first layer, while the red light with the long wavelength permeates to the under layers. We have confirmed that our screen has the analogous optical mechanism of human skin in terms of the color dependence.
The molecular dynamics simulation technique is advantageous in clarifying the relationship between atomistic structure and properties, which are difficult to measure by experiment;it is a powerful tool for developing electrophotographic materials. On the other hand, problems with applying this technique to larger molecules consist of controlling the calculation time and enlarging the scale of simulation. As a countermeasure, the coarse-grained model, which groups atoms or monomers as one particle, is proposed. First, accuracy and performance are investigated by the coarse-grained united-atom model by applying it to polycarbonate. The united-atom model shows good parallel performance. This model has equivalent accuracy, and an expanded speed and spatial scale of simulation by one digit more than ever before. Next, the united-atom model is applied to charge transfer material, and good calculation accuracy is verified. Finally, the highly coarse-grained Kremer-Grest model is shown to be an additional digit faster than the united-atom model.
Since the beginning of 1960s, a lot of organic semiconductors have been developed and used in many applications such as organic photoconductors (OPCs), organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic thin film transistors (OTFTs). To make these applications be commercialized, charge transport property in organic semiconductor should be improved. In the article, we present several computational methods to predict charge transport in organic semiconductor materials at a molecular and a device level. These methods make important roles in understanding the factors influencing charge transport at different circumstances and different scale levels. Furthermore, these methods can be used to improve the charge transport by designing the molecular structures and device architectures.
When we analyze electronic properties of charge transport materials by quantum chemical simulation, computational cost is high for large molecular systems. A fast quantum chemical simulation method, called fragment molecular orbital (FMO) method, has been applied intensively to biological macromolecules. In order to apply FMO materials, one has to test various fragmentations (division of the molecular system into fragments) and find the best scheme. For biochemical systems, such tests have been previously conducted and in this work, an appropriate fragmentation is reported for charge transport materials. Therefore, we examined the computational efficiency and accuracy of FMO for two types of charge transport materials, in which fragments are standalone molecules and in which fragments are connected by covalent bonds, and verified that our fragment models are adequate for practical use.
Organic optoelectronic materials are under widespread development to complement or displace existing materials. These materials are selected or designed according to their internal optoelectronic and condensed-phase properties with concern for efficient charge injection and transport, and desired chemical and thermophysical stability. The chemical design space for organic optoelectronic materials is enormous and there is urgent need for the development of computational approaches to help identify the most promising solutions for experimental development, and to advise the selection of materials for use in optimized applications. In this paper we present examples of atomic-scale simulation approaches available to analyze and evaluate potential organic material solutions for diverse applications, with an emphasis on organic light-emitting diode (OLED) materials.
We demonstrated supercomputer-aided analysis of polymer nanocomposites, which are polymer networks filled with nanoparticles, by X-ray scattering analysis and coarse-grained molecular dynamics (cgMD) simulations. We performed large-scale cgMD simulations with about 10M particles and 10M bonds for three different morphologies of 512 nanoparticles in order to show that the behaviors of stress-strain relations largely depend on the morphologies of the nanoparticles. In addition, we presented a reverse Monte Carlo modelling method for ultra-small-angle X-ray scattering (USAXS) data of nanoparticles. For reported USAXS experimental data for the nanoparticles in “modified” or “non-modified” polymers at BL19B2 of SPring-8, we estimated 3d configurations of 4M nanoparticles. We found that a difference in degrees of nanoparticle aggregations can be seen.
Soft matter, such as resins and rubber materials, has a multiscale structure. Computer simulation is an effective tool for understanding the mechanism of how the physical properties are exhibited. However, it is necessary to properly use the methods for each scale, from the atomistic to the micrometer scale. The integrated simulation system for soft matter, “J-OCTA” includes several modeling tools and simulation engines to conduct multi scale simulation. Simulation technologies for soft matter are introduced here through the functions of J-OCTA and some case studies, such as glass transition temperature of resins, micro structure and mechanical properties of filler dispersed resins or rubbers, rheological properties of entangled polymers, and morphology and wetting property of droplet on a wall.
In the present review, brief explanations are provided for basic theoretical calculations and then some useful program codes are introduced together with the corresponding graphical user interface (GUI) software programs. The most important point is the fact that density functional theory (DFT) is different from molecular orbital (MO) theory, even though the calculations of both theories can be performed by using the same quantum chemistry program codes. The combination of quantum chemistry program codes and their related GUI software programs is now regarded as one of experimental tools. The author hopes that this review will be a trigger to start using quantum chemistry calculations and will help the users correctly understand what kinds of theoretical calculations are employed and how reliable they are for their target molecules.
Material properties are microscopically governed by electrons moving in the crystal lattice of ions. First-principles electronic-structure theory on the basis of quantum mechanics and statistical physics is a powerful fundamental basis of material simulations, because it is independent of experimental measurements. Large-scale computations on supercomputers such as the K Computer of RIKEN and TSUBAME of Tokyo Tech enable us to deepen the fundamental understanding of novel material properties as well as to design new materials in a computer. Examples of practical simulations include microstructure interfaces of hard-magnetic intermetallic compounds and nanostructures relevant for nano-science. Thermal properties and magnetization dynamics can be simulated by combining first-principles calculations and spin-lattice models.
We present the powerful functionality of Silvaco's device simulator in simulating complex organic materials and devices. We then show selected topics of interest on the characterization of electrical and optical properties of organic light emitting devices with numerical simulations.
Organic thin-film solar cells attract rising attention as a next generation materials. However, a detailed bulk structure is not understood. In this calculation, we applied the method combining MD simulations and QM calculations. For C60 and H2PC, and PCBM and P3HT mixture, the bulk structure was clarified by MD simulations. It was observed that P3HT coiled PCBM molecule. The career generation mechanisms were confirmed by B3LYP/3-21G* level QM calculations with TD-DFT method to extracted structures obtained from MD simulations. It was explained that p-type donor molecules were excited by visible light and then an electron moves from acceptor to a hole of donor molecules.
Subjective (psychophysical) and objective (electroencephalography) evaluations of high frame rate and microstereopsis as enhancers of reality in motion images demonstrated that the human perceptual limits of blur and jerkiness are nearly reached with a frame rate of 240fps, which eliminates degradation of quality. Higher frame rate improves the correctness of depth perception of stereoscopic motion images. A camera incorporating a 3D-microstereopsis optical system was developed that, together with 240-fps display and editing systems, presents smooth motion and natural sense of depth. The electroencephalogram when viewing motion images at 240fps were more similar to that when viewing a real motion image than when viewing at 60fps. High frame rate results in human brain activity that resembles the state upon looking at real world scenes. In the future, further studies of motion images using these approaches would be necessary in order to achieve the realization of higher image quality.