Session Index

We successfully developed a mode-selectable and temperature-controlled guest–host smart window. This achievement was realized by adjusting the concentration of a thermoresponsive chiral dopant along with a typical left-handed chiral dopant to optimally manipulate the gap-to-pitch ratio. Additionally, we harnessed the properties of a dual-frequency liquid crystal as the host. This innovative window offers both switchable normal- and reverse-modes, each capable of modifying the switching temperature by applying a low voltage with varying frequencies. Moreover, both modes can actively adjust transmittance at will. This design provides an expanded range of control options and holds significant potential for practical applications.

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By exposing polymer-cholesteric liquid crystal (CLC) composites to ultraviolet
(UV) light, a polymer-separated double-layer structure can be formed due to the uneven
polymerized reactions of polymers in the top and bottom regions, respectively. This doublelayer cholesteric structure exhibits two reflection bands, allowing the reflection bandwidth in
CLCs to be broadened. The broadened bandwidth allows light to be manipulated in novel
ways, enabling the development of advanced optical devices with improved performance.

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This report proposes a device possessing both electrochromism and dichroism, and both properties can be individually controlled by direct current (DC) and alternating current (AC) electric fields. A color-mixing result can be also obtained by applying DC and AC electric fields at the same time.

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This work demonstrates two-photon polymerization direct laser writing (2PP-DLW) in polymer-stabilized nematic liquid crystals. The writing parameters, including laser power, writing velocity, writing repetition, and writing route, are discussed. According to the writing parameters, the patterned polymer-stabilized nematic liquid crystals can be transparent or opaque, which can result in the polarization modulation of light and scattering, respectively. With the electric-optical response of liquid crystals, electrically controllable phase or amplitude diffraction elements can be fabricated by this technique and applied to hidden optics or planar optics.

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This study proposes a unique electrode structure design for accelerated development
of near-infrared (NIR) OLEDs. Silver nanoparticles coated with titanium dioxide, followed by
ITO deposition, create a transparent electrode with localized surface plasmon resonance. Red
phosphorescent OLEDs on these electrodes utilize an exciplex system to optimize efficiency
and reduce operating voltages. The dopant used in OLEDs is an efficient deep-red
phosphorescent material, Ir(fliq)₂acac, with a wavelength of 650 nm. The results demonstrate
that this unique electrode design transforms deep-red light-emitting devices into near-infrared
devices with adequate efficiency. This design overcomes NIR material development limitations,
opening new directions for future advancements.

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Six donor-acceptor-donor (D-A-D) materials were designed and synthesized as efficient hosts for red phosphorescent OLEDs. These compounds, using three types of acceptors (TXO, DBTS, and SpDBTS) with phenyl-carbazole (CzP or PCz) donors, demonstrated triplet energy gaps higher than the emitter (Ir(piq)₂acac), ensuring effective energy transfer. Blending the synthesized compounds with CN-T2T improved carrier balance. Among them, the DBTS-CzT/CN-T2T mixed host showed excellent EL characteristics with a high efficiency of 21.7% (13.4 cd/A) and a low turn-on voltage of 2.2 V. These results highlight their potential for use in efficient red phosphorescent OLEDs.

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Using magnetic field effects analysis, we report a significant change between tetracene-only and tetracene/C60 devices, after we deposit the C60 on the tetracene active layer, we got a huge different line shape in magneto-photocurrent (MPC) and photoluminescence (PL) which indicates that the tetracene/C60 device will form CT-complex (Charge Transfer complex). In addition, we further confirm this result from magneto-current (MC) and magneto-electroluminescence (MEL), We can verify that with and without C60 have a big effect on tetracene-based devices, and the main reason is the formation of the CT-complex.

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Two 2,7-dicyaonfluorene-based molecules are utilized as acceptors (A) to combine with hexaphenylbenzene-centered donors (D) for probing the exciplex formation. To further utilize the exciton electrically generated in exciplex-forming system, the D-A-D-configurated fluorescence emitter DTPNT is doped into the DDP-HPB:27-tDCN blend. The nice spectral overlap ensures fast and efficient Förster energy transfer (FRET) process between the exciplex-forming host and the fluorescent quests. The red device adopting DDP-HPB:27-tDCN:5 wt% DTPNT as the EML gives EL λmax of 655 nm and EQE of 6.1%.

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We designed three kinds of hole-transporting materials that use a phenyl or a pyrimidine to connect two 3,6-bis(trifluoromethyl)-9-methyl-9H-carbazole moieties with a different substitution. These compounds have an adequate energy bandgap suitable as host materials for green emitters. These materials are combined with B3PyMPM in a 3:7 ratio to construct a mixed host in the devices. As a result, the CFCz2/B3PyMPM-based OLEDs with Ir(ppy)₃ green emitter has the best performance, achieving a peak efficiency of 19.8% (68.4 cd/A, 85.0 lm/W), a low turn-on voltage of 2.4 V, and high maximum luminance of 91141 cd/m².

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We designed a series of bicarbazole-based hole-transporting materials where two
carbazole moieties were connected at different positions to synthesize four compounds. These compounds have an adequate energy bandgap suitable as host materials for green emitters. These materials are combined with B3PyMPM to construct a mixed host in the devices. As a result, the H4/B3PyMPM-based OLED with Ir(ppy)₃ green emitter has superior performance, achieving a peak efficiency of 24.1% (84.5 cd/A, 110.6 lm/W), a low turn-on voltage of 2.2 V, and high maximum luminance of 87113 cd/m². These results demonstrate the effectiveness of our molecular designs and the device architectures.


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Through the strategic optimization of the donor-to-acceptor ratio within the emissive layer (EML), effective conduction within the exciplex-based OLED is achieved. This optimization culminates in a notable enhancement of the external quantum efficiency of the exciplex-based OLED, elevating in to 8.51%.

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In this work, the exciton diffusion model coupled with a drift-diffusion solver is used to simulate the hyper-TTF-OLEDs devices. We analyze the efficiency and loss mechanisms to demonstrate that the main reason for internal quantum efficiency (IQE) loss is the triplet-polaron quenching (TPQ) and the ability of triplet exciton diffusion. In device with PPC EML, the TPQ is the weakest, and triplet diffusion is the best. Hence, triplet excitons efficiently transfer to the NPAN layer and improve the triplet-triplet fusion (TTF) and IQE. The above results also confirm the excellent IQE in device C, which reaches up to 34.1%.

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We develop quantum-dot (QD) vertical light-emitting transistors (QVLETs) by integrating ZnO transistors and QLEDs based on the encapsulated source electrode transistor geometry, and modify the nanocrystalline ZnO and polyethyleneimine (PEI) blend film as the electron injection layer (EIL) for device optimization. By blending an appropriate PEI ratio in the EIL, we achieve the optimal device with the highest external quantum efficiency of ~3% and uniform emission in the ZnO transistor channel area. This QVLET design features high performance and a controlled emission area, making it suitable for developing high-resolution display applications.

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This study focuses on the charge generation layer (CGL) structure to design more efficient tandem OLEDs with higher efficiency and brightness. We proposed a specific design of a CGL structure, which inserted a thin layer of Li₂CO₃ between the double organic heterojunction (OHJ) pair. The current density of the proposed CGL device exceeded the control CGL device. Furthermore, the tandem device with the proposed CGL exhibited much higher EL performance than the conventional CGL with double OHJ pairs. This result demonstrates that our proposed CGL design effectively simplifies the device architecture and improves efficiency.

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Luminescent carbene-metal-amide complexes bearing group 11 metals have drawn
significant attention due to exceptional emission and high radiative decay rates. Herein, a
newly developed Cu(I) complex bearing carbenes has been investigated and analyzed
concerning their light emission properties and OLED application. After finetuning the device
architecture, four different doping concentrations were adopted to maximize the EL
performance. The results revealed that the green TADF device with a doping concentration of
15 weight percent demonstrated the highest efficiency of 8.6% (26.3 cd/A), indicating the
potential of the synthesized complex for TADF emission.

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Blue organic light-emitting diode based on triplet-triplet annihilation (TTA) was demonstrated with boron-containing anthracene as the host of the emitting layer, together with bilayer structure, which achieved a current efficiency of 13.65 cd/A, a power efficiency of 11.96 lm/W, and an external quantum efficiency of 10.35%.

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In this work, a series of deep-blue thermally activated delayed fluorescence (TADF) emitters were developed based on macrocyclic donors. Thorough investigations on photophysical properties of the emitters were carried out to establish the structure-property relationship and verify the progressive hypsochromic shifts. Also, in the presence of macrocyclic donors, these new emitters show high horizontal dipole ratios. The efficient TADF character, high photoluminescence quantum yields, and high anisotropic emission dipole ratios work together to render the superior electroluminescence (EL) efficiencies, together with satisfactory deep-blue emissions.

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Micro-light emitting diodes (Micro-LEDs) displays with remarkable advantages are becoming mainstream in next-generation displays technology. However, further development of Micro-LEDs still encounters significant challenges, including mass transfer yield. In this study, we employed the color conversion layer (CCL) technology and doped the nanoparticles (NPs) into the transparent photoresist. The quantum yield (QY) variations of ZnO and SiO2 NPs are investigated. We achieve up to 70.6% QY and absorbance 93.0% in dual path measurements. This lays the foundation for achieving high-performance Micro-LEDs displays for AR/VR applications achieved pixel miniaturization in the future.

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A series of cationic complexes of general formula [(C^C)Au(P^P)]X, where C^C = 4,4'-di-tert-butyl-1,1'-biphenyl, P^P is a diphosphine ligand and X is a non-coordinating counter-anion, are employed as the electroactive materials of the first proof-of-concept light-emitting electrochemical cell (LEC) devices. These complexes show emission maxima in the green-yellow region with moderate to high photoluminescence quantum yields. The LECs achieve peak external quantum efficiency, current efficiency, and power efficiency up to ca. 1%, 2.6 cd A-1, and 1.1 lm W-1, respectively, showing the potential use of these novel emitters as emissive compounds in LEC devices.

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In this study, pyrene-carbazole (PC) derivative was used as one host material for blue fluorescence organic light-emitting diode (OLEDs) exhibiting bilayer emitting layer (BEML) structure, which consisted of PC and anthracene as the hosts, respectively. By optimizing the dopant concentration of PC-EML, maximum current efficiency (C.E.max) of 15.40 cd/A, maximum power efficiency (P.E.max) of 10.92 lm/W, maximum external quantum efficiency (EQEmax) of 11.13% and CIE coordinates of (0.139 0.210) were achieved in this blue OLED.

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In this research, a novel host material with anthracene moiety was used for blue organic light-emitting diodes (OLEDs). By incorporating dopants into the emissive layer (EML), the device achieved a maximum current efficiency (CEmax) of 8.31 cd/A, a maximum power efficiency (PEmax) of 7.45 lm/W, Commission Internationale de l'Eclairage (CIE) coordinates of (0.144, 0.196), and a peak emission wavelength at 462 nm. And the maximum external quantum efficiency (EQEmax) reached 5.43%.

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Micro light-emitting diode (Micro-LED) are gradually becoming the mainstream technology for high-end displays. This research achieves a full-color Micro-LED display by combining a color conversion layer (CCL) with a blue-light Micro-LED array. To enhance the color conversion layer and reduce pixel size, nanoparticles are utilized in the CCL, and a process is designed to address nanoparticle accumulation in the pixel array. In the fabrication of a 4×4 μm pixel array, the pixel density reaches 5080 PPI for single-color and 2540 PPI for full-color displays. By achieving a nanoparticle-enhanced full-color Micro-LED display, our results offer further possibilities for display technology.

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The performance of deep ultra-violet light-emitting diode may be improved by implementing graded layers for both electron-blocking layer and short period superlattice. Reduction in operation voltage is obtained, which is attributed to the reduction in polarization effect. Moreover, in order to reduce the influence of relatively large Auger nonradiative recombination rate in deep ultra-violet spectral range, the number of quantum wells is further increased to eight to reduce the carrier concentration in each individual quantum well. The overall nonradiative recombination rate in the active region is decreased and hence the performance of deep ultra-violet light-emitting diode is further improved.

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We present an innovative smart window that employs dye-doped dual-frequency liquid crystal (LC) to enable electrically and thermally controlled reverse-mode operation. The devised window automatically adjusts its transparency in response to temperature, ransitioning between two optical states corresponding to two distinct levels of transmission. This smart window benefits from the unique properties of dielectric anisotropy tunability, permitting it to switch between distinct optical states including dynamic scattering at specific electric-field frequencies. We conducted an in-depth study of the temperature-dependent dielectric anisotropy of the material. Our research provides a new pathway toward applications in sensor-based optical devices.

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Nematic liquid crystals (NLCs) composed of rod-shape molecules and bent-shape molecules, were added with chiral dopant to form cholesteric liquid crystals (CLCs). A mixture was formed by doping a small amount of monomers to cholesteric liquid crystals. The ULH (uniform lying helix) structure was obtained through a cooling-induced phase transition. A UV light was used to polymerize the monomer to stabilize the ULH structure. Applying a pulsed electric field to unwind the helical axis results in a mixed state, which applied with a pulsed electric field at a lower voltage, can be switched back to the ULH state.

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In this study, it is proposed that electrically driving liquid crystal lenses are investigated optical aberrations by means of interferogram analysis. Liquid crystal (LC) lenses possess a specific capability of electrically tunable focuses belonging to the type of GRIN (gradient refractive indexes) lenses, which propagating optical rays through the lens itself are curved trajectories rather than straight lines in the refractive lenses. In order to clearly analyze the imaging capabilities of electrically driving LC lenses, the interferogram analysis of Twyman-Green interferometer is used.

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In this research, a pyrene-benzimidazole derivative was synthesized and employed
as host of the emitting layer in blue fluorescence organic light-emitting diode (OLED), which achieved maximum external quantum efficiency (EQEmax) of 7.7% with the Commission Internationale de l'Eclairage (CIE) coordinates of (0.14, 0.23).


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