Dual-mode Display Research Articles

Dual-Mode Multicolor Display Based on Structural and Fluorescent Color CdS Photonic Crystal Hydrogel.

In this study, we prepared a multicolor structural-fluorescent CdS-PEGDA photonic crystal hydrogel (SFC-CPH) with a dual display mode, which has two different optical states: structural color mode and fluorescent color mode. SFC-CPH displays structural color mode under visible light and fluorescent color mode under ultraviolet light. Initially, monodisperse CdS colloidal particles were synthesized via a hydrothermal method, leading to the self-assembly of a photonic crystal template. The high refractive index of CdS contributes to the photonic crystals' low-angle dependence and vivid structural colors. Then, a variety of fluorescent molecules were doped into poly(ethylene glycol) diacrylate (PEGDA) hydrogel and combined with photonic crystals with distinct structural colors to prepare three distinct colors of SFC-CPH. We also investigated the optical characteristics and surface properties of these photonic crystal hydrogels. Based on these dual-mode display characteristics, we designed several dual-mode display patterns and a method for information encoding. The unique property of this photonic crystal hydrogel material suggests its substantial potential for applications in information storage, security, and encoding, offering innovative avenues in the realm of information display.

Engineering luminescence switching and photochromic performance in tungsten bronze oxides for handwriting display based on variable valence ion strategy

Inorganic luminescence materials with intelligent response to external stimuli have drawn considerable interest owing to their alluring applications. Photochromic (PC) is a reversible process which can be adopted to construct subtle luminescence regulation. However, the PC effect is commonly weak for most inorganic materials. It is still challenging to realize strong luminescence switching and PC effect in general inorganic compounds. To fill this gap, tetragonal tungsten bronze (TTB) oxides with ingenious upconversion (UC) luminescence modulation and prominent PC phenomenon were designed by introducing variable valence ion (Mo6+). Under this decorating, the UC luminescence switching ratio and PC contrast could be increased up to 2 and 4 times, respectively. The real-time information encoding based on PC and UC modulation was realized in TTB wafer, confirming the instant handwriting dual-mode display capacity. It is believed that this work will shed new light on the designing of terminal display devices.

Bio-derived chlorophyll dye doped cholesteric liquid crystal films and microdroplets for advanced anti-counterfeiting security labels

Herein, we have shown security codes based on an advanced anti-counterfeiting material that are difficult to duplicate and are substantially distinct from the present technology. The anti-counterfeiting material can be made by dispersing green synthesized chlorophyll from spinach leaves into cholesteric liquid crystal (Red, Green and Blue reflections). The resultant anti-counterfeiting material reflects color in daylight (Red/Green/ Blue) due to the reflection property of CLCs and magenta color in UV light due to the fluorescence property of chlorophyll. Furthermore, we have shown that anti-counterfeiting material confined to spherical microdroplets produced by glass capillary microfluidic approach exhibit dual-mode display and security ink properties under daylight and ultraviolet light, including authenticate/non-authenticate QR codes, implying their potential applications in anti-counterfeiting technologies for the protection of valuable objects. These color variations are easily detectable in real time and may be used to create anti-counterfeiting patterns with color changesin both reflection and fluorescence modes. Because of the easy technique, we believe this can give a new platform for numerous security and color-based applications that is more cost-effective and environmentally friendly than traditional approaches.

Electrochromic/electrofluorochromic poly(urea-urethane) bearing oligoaniline and tetraphenylethylene groups: Synthesis, characterization, and H2O2 visualized determination

The elegant electroswitchable color/emission properties of electrochromic/electrofluorochromic dual-functional materials motivates the exploration of their new applications. In this work, a new poly (urea-urethane) was synthesized via nucleophilic copolymerization of electroactive oligoaniline derivative, solid-emissive tetraphenylethylene groups, and alkyl isocyanate. The resultant poly (urea-urethane) exhibited good electroactivity and desirable aggregation-induced emission properties. High-performance electrochromic/electrofluorochromic behavior had been disclosed with a high optical contrast ratio of ΔT = 50.4%, a moderate fluorescence on/off ratio of 10.5, and high coloration efficiency of 503 cm2/C at 768 nm. A reflective/emissive dual-mode display device had also been manufactured based on the resultant poly (urea-urethane) and charge-balancing V2O5, exhibiting a reversible color change and tunable fluorescence conversion upon the electric stimulus. Furthermore, this polymer showed an interesting color/fluorescence response to H2O2, due to the linkage mechanism between its redox states and optical properties. The spray-coated poly (urea-urethane) test strips were employed in visualized dual-determination of H2O2 with gradual color change from gray to dark green, along with an obvious fluorescence change from light blue to dark, which displays easy operation and rapid detection.

Simultaneously achieving high capacity storage and multilevel anti-counterfeiting using electrochromic and electrofluorochromic dual-functional AIE polymers.

With the advent of the big data era, information storage and security are becoming increasingly important. However, high capacity information storage and multilevel anti-counterfeiting are typically difficult to achieve simultaneously. To address this challenge, herein, two electrochromic and electrofluorochromic dual-functional polymers with aggregation-induced emission (AIE) characteristics were rationally designed and facilely prepared. Upon applying voltages, the absorption and fluorescence spectra of the AIE polymers can undergo reversible changes, accompanied by variation of their color and emission. By utilizing the controllable characteristics of the polymers, dual-mode display devices were fabricated via a simple spraying technique. More interestingly, a four-dimensional color code device was constructed by adding color change multiplexing to the two-dimensional space, thereby achieving high capacity information storage. Moreover, the color code device can also be applied in the multilevel anti-counterfeiting area. The encrypted information can be dynamically converted under different voltages. Thus, the AIE polymers show great promise for applications in multidimensional information storage and dynamic anti-counterfeiting, and the design strategy may provide a new avenue for advanced information storage and high security technology.

Light- and space-adaptable display

ABSTRACTPresented is a flexible dual-mode display operable in reflective and emissive mode according to ambient light for optimal visibility on a nonplanar surface. Flexible-backplane-embedding organic light-emitting diodes (OLEDs), thin-film transistors (TFTs), and control electrodes for liquid crystal (LC) shutter are realized by the laser lift-off (LLO) method and the newly developed polyimide (PI) delamination technique. A novel color-filterless LC shutter with color dyes is merged with this flexible backplane for operation in reflective mode. This work opens up a promising approach to building displays that are adaptive to the surrounding environment for better usability.

(Invited) Electrochemically Controllable Emission and Coloration Using Luminescent Europium(III) Complex and Electrochromic Viologen Derivatives

A dual-mode display (DMD) device which can operate in both emissive and reflective modes, having advantages of both modes, is considerable promise as a next generation display. Using the dual-mode display, we can choose either reflective or emissive mode as the situation demands. However, only a few studies have been reported on the DMD devices because it should include two different mechanisms in one device. For creation of novel materials enabling electrochemical modulation of both emission and coloration, we focused on the concept of “emission control based on EC reactions”. By combination of luminescent material and EC material, the energy transfer between the two materials can be controlled by EC reactions. When the EC molecule is colorless state, the energy gap between ground state and excited state of the EC molecule is larger than that of the luminescent material. Therefore, under the photo- excitation of the luminescent material, the transfer of excitation energy from luminescent material to EC material is not allowed, leading to bright emission from the luminescent material, i.e. “emissive mode”. When the EC molecule is colored, on the other hand, the energy gap of the EC molecule became smaller than that of luminescent material. In this state, the excitation energy is expected to transfer to the colored EC molecule from luminescent material. Since the energy transfer will quench the luminescence, only coloration of EC molecule can be obtained without photoluminescence, i.e. “reflective mode”. Here, we have tried to control coloration as well as emission based on electrical stimuli by combination of photoluminescent and EC materials to achieve a novel DMD material. In this paper, the electrochemical switching systems enabling the control of the both modes were investigated. Furthermore, a prototype DMD device with emissive and coloration based on electrochromism were fabricated. We first demonstrated both luminescence and coloration control by using a composite material containing a luminescent Eu(III) complexes and electrochromic viologen derivatives as the luminescent and coloration materials, respectively. The coloration of the composite material was controlled by the electrochromic reaction of viologen derivatives. Modulation of red emission from Eu(III) complex was also achieved by the electrochromism of viologen derivatives via intermolecular energy transfers from the excited states of Eu(III) ions to colored viologens. The 2-electrode cell containing the luminescent complexes and electrochromic molecules functioned as an electrochromic device when bias voltage was applied and as a light-emitting device if excitation lights are irradiated. When bias voltage was not applied to the cell, the outer appearance of the cell was clear transparent, the strong red emission from Eu(III) complex was observed under UV excitation. This can be considered as ‘emission on’ state. On the other hand, after application of voltage ca. 2 V, the cell changed from clear transparent state to colored state by electrochromic reaction of the viologen derivatives, resulting in ‘refection on’ state. As the coloration of the cell, red emission of the Eu(III) complex was completely quenched under colored state. In order to achieve a rapid fluorescence modulation response, it is necessary to immobilize both luminescent and electrochemically active molecules on the same electrode because response times of modulation of both emission and coloration are dependent on the response time of electrochromism and energy transfer efficiency. We finally tried to fabricate photo-electro functional modified electrode incorporating the Eu(III) complex and viologen derivative on the electrode. The novel modified electrode was fabricated by covalently- connecting the Eu(III) complex and viologen derivatives on porous TiO2 electrode through carboxyl groups or phosphate groups. The immobilizing of these materials on porous TiO2 electrode is expected to achieve absorption and fluorescence intensity, because large surface area of the TiO2 film allows the increase of adsorption amount of the materials, leading to high emission contrast of modulation. The adsorption amount of the Eu(III) complex and viologen derivative were analyzed by FT-IR and EDX measurements. The modified electrode showed strong red photoluminescence from the Eu(III) complex at transparent state. The EC reaction of the viologen derivative was also observed with rapid response of few seconds by applying -0.8 V. The photoluminescence from Eu(III) complex was successfully modulated by EC reaction of the viologen derivatives within few seconds.

An electrochemically-driven dual-mode display device with both reflective and emissive modes using poly(p-phenylenevinylene) derivatives

We demonstrate a novel electrochemical dual-mode displaying (DMD) device, which enables control of both coloration and light emission using an electrochemical reaction. The coloration control of the DMD device was based on an electrochromic (EC) reaction, whereas the light emission of the device was caused by an electrochemiluminescence (ECL) mechanism. This novel DMD device consisted of a pair of facing conductive polymer-modified electrodes: comb-shaped interdigitated Au electrodes modified with poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) layers and poly(2,3-dihydrothieno-1,4-dioxin)–poly(styrene sulfonate) (PEDOT/PSS) film-modified indium tin oxide (ITO) electrodes. When a bias voltage was applied between the PEDOT/PSS film-modified ITO electrode and the comb-shaped electrodes, a color change of the device was observed by the EC reaction of the MEH-PPV and PEDOT/PSS. On the other hand, an emission was obtained when the bias voltage was applied between two comb-shaped interdigitated electrodes. The orange emission was ascribed to the ECL reaction of the MEH-PPV layer, which resulted from the formation of a p–i–n junction in this layer.

Thermally controlled dual-mode display media with red-green-blue coloration and fluorescence via energy transfer between emission materials and leuco dyes

Thermo-responsive multifunctional composite materials enabling red-green-blue (RGB) control of both emission and reflection were fabricated.

Color e-Paper Technology with Electrochemistry

The demand for global environmental conservation and decrease of CO2 evolution require the development of “new imaging media”, instead of paper. This is called “electronic paper (e-Paper)”. Electrochromism (EC) is defined as a reversible color change by electrochemical reaction and has several features such as color variation, memory property and so on. Electrochromic display (ECD) is therefore a potential candidate to realize full color e-Paper. EC materials showing color changes from clear to the three primary colors such as RGB or CMY should be required to realize full color e-Paper. This paper focuses on novel e-paper technology with electrochemical reaction. First, we will show our recent results on EC materials and devices which show three primary colors (CMY) in subtractive color mixture system1, 2. Electrodeposition is also attractive method to create colors3-5. We will discuss the mechanism of electro-deposition and a wide range of its applications. We also demonstrated novel display device with dual reflective and emissive modes. This is called dual mode display (DMD). DMD enables both reflective and emissive mode of representation which can be chosen as a situation demand. We fabricated DMD by combining both electrochromic (EC) and electrochemiluminescence (ECL) materials in a single cell6, 7. The device functions as an EC cell in the reflective mode, and as an ECL cell in the emissive mode.References; 1) Solar Energy Materials and Solar Cells, 92 136 (2008), 2) Solar Energy Materials and Solar Cells, 104, 140 (2012), 3) Adv. Mater., 24, OP122 (2012), 4) Adv. Mater., 25, 3197 (2013), 5) Chem. Mater, 26, in press (2014). 6) Chem. Lett., 39, 1309 (2010), 7) Phys. Chem. Chem. Phys., 13, 19420 (2011).

Towards a Software Tool Supporting Urban Decision Makers in Locating and Sizing the Household Garbage Accumulation Points Within Cities

Locating and sizing garbage bins for the separate accumulation of household solid waste within urban areas is of primary interest for the local administrations that so far lack adequate IT support. The paper highlights the versatility of a method for solving such a problem, which involves both standard and geographic data. Implementation of the proposal, centered around a spatial database, goes in the direction of developing a supporting software tool to the officials responsible for the management of municipal solid waste. They are offered a dual-mode display of the results: one tabular (the standard format featured by relational databases) and the other based on the metaphor of geographic maps, the latter being particularly useful in capitalizing on the spatial component of the problem.

Integration of Spatial and Descriptive Information to Solve the Urban Waste Accumulation Problem: A Pilot Study

The paper reports about a pilot study that gives a numerical solution to the solid waste accumulation problem (SWAP). The purpose is to show both a simple and effective way to implement the theory using the technology of the Spatial DataBase Management Systems (SDBMSs), and the versatility of the proposed solution from the point of view of those responsible for the MSW management who, in fact, are offered a dual-mode display of the results: one tabular (typical of relational databases) and the other based on geographical maps, the latter particularly useful to highlight the spatial component of the data of the SWAP.

Electrochemical Materials for Novel Light Emitting Device and Dual Mode Display

Electrochemical Materials for Novel Light Emitting Device and Dual Mode Display

Reflective and Emissive Dual Mode Display Cell with Electrochromism and Electrochemiluminescence

We are studying novel dual-mode display (DMD) driven by electrochemical reaction. Our DMD cell shows electrochromic (EC) properties as reflective mode and electrochemiluminescent (ECL) properties as emissive mode. In this paper, we reported the effect of structure and materials on characteristics of reflectiveemissive dual-mode display cell.

Improvement in reflective–emissive dual-mode properties of electrochemical displays by electrode modification

We studied the electrochromic (EC) and electrochemiluminescent (ECL) properties of a novel dual-mode display (DMD) cell that was enabled for reflective and emissive modes of representation by introducing both EC and ECL materials into an electrochemical cell. We fabricated EC, ECL, and DMD cells based on a simple-mixture solution or modified electrodes and compared their properties to clarify the advantage of a DMD system based on modified electrodes. Both the solution- and modified electrode-based DMDs showed EC properties in the reflective mode under dc bias application and ECL properties in the emissive mode under ac bias application. Although the solution-based DMD cell featured a very simple structure, some improvements related to side reaction and quenching reaction were required. The modified electrode-based DMD cell was fabricated to improve these aspects. The advantage of the DMD model based on the modified electrodes was certainly suggested by comparisons of the results with those of EC, ECL, and DMD cells based on a simple-mixture solution.

Fabrication of Novel Reflective–Emissive Dual-mode Display Cell Based on Electrochemical Reaction

Abstract We successfully demonstrated a novel reflective–emissive dual-mode display (DMD) cell with electrochromic and electrochemiluminescence reactions. This DMD cell has simple structure and allows the selection of reflective or emissive mode by selecting DC or AC driving, respectively.