Session Index

Previously, we have reported the three-dimensional pixel configuration, which the design of the structure is capable of achieving several-times outcoupling enhancement. In the former report [1,2], the multiscale simulation was partitioned into two different space domains where the OLED stacks and high-index filler region belonged to wave optic and geometrical optic domain respectively. However, the simulation result is far from the experimental spectrum with an observable interference peak wavelength. In this work, we present a novel method to implement the 3D pixel configuration with the fully electromagnetic wave theory. The optical simulation results are in good agreement with experiments.

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The optimal trichromatic white LED spectra, which have higher luminous efficacy and a wider 3D color gamut range of human skin color under 1,000 lx are proposed. Three kinds of optimal spectra are recommended for commercial lighting to improve visual perception in the study.

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We conducted a systematic design on epitaxial structure and grating of 1060nm distributed-feedback (DFB) semiconductor laser. The design includes the optimization of threshold, slope efficiency, and gain margin of lasing characteristics. Furthermore, the influence of the process error of grating structure was also investigated.

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The light extraction of deep ultraviolet light emitting diodes (DUV LEDs) is studied in this report. By the thermal oxidation process, the refractive indexes of the sidewalls of DUV LEDs are modified. The oxidized sidewalls possess lower refractive indexes which are beneficial to light extraction. The output powers of DUV LEDs are increased by the enhanced light extraction, and the enhancement of output power range from 20 to 27% by varying the thicknesses of oxidation layers.

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MAPbBr3 single crystal material was grown by inverse temperature growth method, and then MAPbBr3 perovskite quantum dots were synthesized by ligand-assisted precipitation method. Different purification times were compared to find the best material parameters.

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In this paper, a novel gate driver on array circuit based on hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) has been proposed for a negative pulse. Different with normal GOA circuit, the proposed circuit can output a negative pulse and the problem of short-circuit current could be solved. In addition, the charged structure reduces the rising time of pre-charge node to enhance the operation speed and adds the higher voltage to reduce the Vth of source follower. The simulation results show that the proposed circuit could pass the verification at 85°C and −40°C.

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Through doping engineering and interface modification engineering, potassium bromide (KBr) was doped into the NiOx hole injection layer (HIL) and an interface modification layer was inserted between the HIL and the perovskite film. The prepared PEACs0.9Rb0.1PbBr2.1Cl0.9 sky blue quasi-2D perovskite light-emitting diode achieves an external quantum efficiency of 7.23%.

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The application of CGH display technology to AR multi-depth head-up displays is a very popular research topic nowadays. However, the system implementation requires multiple projection devices or spatial light modulators with Freeform Mirror or complex optical mechanisms to present multi-depth projection of automotive head-up display, which does not meet the development needs in terms of system size and cost. In this study, we attempt to realize a miniaturized multi-depth CGH head-up display system with a single spatial light modulator.

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In this paper, the flexoelectro-optic characteristics of uniform lying helix structure in cholesteric liquid crystals are studied, and the factors that affecting the flexoelastic ratio, the slope of the rotation angle of the optical axis to the voltage, and the response time are discussed.

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Through the cooling phase transition, cholesteric liquid crystals (CLCs) form a uniform lying helix (ULH) structure. Meanwhile, the ULH structure undergoes polymer photopolymerization, forming a polymer stabilized ULH state (PSULH). Another steady state can be obtained by applying a vertical electric field to unwind the helical axis and then removing the voltage instantaneously. This steady state may be a mixed state, which shows a unique optical effect of scattering the Bragg reflection wave band. Bent-shape molecules doped into CLCs enhance the optical effect.

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This work describes the effect of a rubidium chloride (RbCl) interlayer in CsPbBr3 perovskite light‑emitting diode (LED) structures. RbCl crystallites exhibited polyhedral structures and lattice parameters similar to those of CsPbBr3 perovskite crystallites. The devices exhibited the best quality and performance when RbCl was used as the nucleation and carrier confinement layer. The crystallite sizes of CsPbBr3 with 0.2‑, 0.5‑, and 1‑nm‑thick RbCl bottom layers were 55.1, 65.4, and 55.1 nm, respectively. The full width at half maximum (FWHM) of the photoluminescence (PL) emission peak for CsPbBr3 with the RbCl bottom layer was 0.096 eV.

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The main goal in this study is to understand the white appearance of an iPad under 3500K and 6500 K with normal office illuminance levels of 600 lx and 1200 lx. A panel of twenty-three observers (11 females and 12 males) participated in this psychophysical experiment. The iPad was carefully adjusted 76 uniformly distributed stimuli in CIE1976 UCS. Each observer rate whiteness percentage of 76 stimuli under 600 lx and 1200 lx with a horizontal CCT. The results show that the CCT of the whitest stimulus under 6500 K is higher than the whitest stimulus under 3500 K.

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In this study, we used a simulated office environment as the experimental space and investigated the influence of lighting’s circadian stimulus (CS) on participants’ concentration. Several concentration indices were tested and the ones with better classification performance between working and resting states were used for the conversion of intuitive concentration score. The brainwave signal processing involves Hilbert-Huang transform (HHT), probability density function (PDF), receiver operating characteristic curve (ROC curve), area under the ROC curve (AUC), and support vector machine (SVM).

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Projection and TV screens as eLearning media might impose threats on eyes, by noting blue enriched white light to be hazardous to retina. To know which is a more eye-friendly medium, a blue-hazard quantification spectrometer was applied to determine the permissible viewing time under a certain viewing clarity. We found that the studied TV screen permitted a 1.3h viewing time while 0.5h for the projector, when viewing a 34pt font at a 2-meter viewing distance.

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A psychophysical experiment is designed to investigate how background color affect visual comfort on an iPad under easy-warm lighting condition. Twenty- observers (18 males and 2 females) join this experiment. Each observer evaluates 66 paired comparisons under easy-warm lighting condition. The results show that the observers tend to prefer the background color on the Planckian locus or above the Planckian locus when reading on the iPad.

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Based on Monte Carlo ray tracing method and Geometry Optics, we simulate a physical model by a commercial software to evaluate the emitting efficiency of micro-LED. With the microlens array design, the light intensity distribution can be improved and reduce the loss efficiently.

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The passivation layer of atomic-layer-deposited Al2O3 and white photoresist can effectively improve the brightness and leakage current of the micro-LED displays. The average leakage current is controlled from 89.3 to 32.1 nA when measured at a reverse bias and the brightness can improve up to 607 nits under 3V.

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This work studied the optical degradation of chlorophyll species obtained from an extract of pongamia pinnata leaves embedded in silicon encapsulation. The silicone film with immobilization of chlorophyll was fabricated. The optical degradation was done under blue light illumination at selected blue light illuminating period. Then the emission spectra of the red light emitting from the chlorophyll in silicone film were collected to illustrate the optical degradation of chlorophyll under blue light illumination.

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Green quantum dot light-emitting diodes (QLEDs) comprised of organic hole injection/transport layers and solution processing magnesium doped zinc oxide (MgZnO) nanoparticles (NPs) electron injection layer (EIL) are demonstrated. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) was used as hole injection layer (HIL) accompanied with Poly-TPD as hole transport layer (HTL). After spin-coating process the PEDOT:PSS thin film was subjected to an additional deionized (DI) water rinse treatment to modify the acidity nature. The fabricated QLED demonstrated operating performance of a maximum luminance (Lmax) up to 759,561 cd/m2 and current efficiency of about 32.4 cd/A.

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In this study, the replicated film of rose petal surface structure is covered onto the top surface of phosphor-converted LEDs (pcLEDs) to improve the color uniformity. The two-phase fabrication process was used to fabricate the replicated film with surface morphology of rose petal. It is found that the minimum perceptible color difference (MPCD) of pcLEDs with replicated film with rose petal surface structure is lower than the ones without the film. That is, the use of replicated film with rose petal surface structure on pcLEDs can reduce the angular color variation, and then improve the color uniformity.

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In this work, we proposed a novel device configuration for efficient ITO-free, top-emitting, and inverted organic light-emitting diodes (OLEDs), which showed low current density, high external quantum efficiency(EQE), and good stability. As a result, the CN-T2T-doped Li exhibits a good electron injection efficiency between the Ag and organic layer. Based on such a concept, our proposed inverted OLED with an extremely low driving voltage of 2.41 V and external quantum efficiency of 22.0% can be achieved.

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Si-based perovskite light emitting diodes (PeLEDs ) possess great potential in displays. However, the contact between silicon substrates and solution-processed perovskite layer is very challenging. Here we overcome the adhesion of perovskite to Si using a sandwich evaporation technique with a handmade cavity in the laboratory, and achieved red, green, and blue stable silicon-based PeLEDs by adjusting the doping of halogen elements. As a result, the fabricated PeLEDs achieved emission wavelengths of 522 nm for green, 660 nm for red, and 477 nm for blue.

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The gallium nitride (GaN)-based blue micro-light-emitting diodes (micro-LEDs) with various luminous areas were produced by photolithography technology. The properties of micro-LEDs with various sizes were measured by the current density-voltage (J-V) curve, electroluminescence spectrum (EL), light output power, and external quantum efficiency (EQE).

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We demonstrated a blue phase liquid crystal (BPLC) device whose photonic bandgap (PBG) can be tuned over the whole visible region (470 nm-770 nm) under weak UV exposure (< 8 mW/cm2) without undergoing phase transition of different BP states. The key role of the outstanding tunability for the BPLC device is the photosensitive molecular motors doped in the CLC host. When irradiated by UV light, whose HTP can be largely tuned under UV irradiation.. This tuning process is reliable, repeatable, and programmable, and thus suitable for use in applications of light switches or modulators in general optics and integration photonics.

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In this study, the temperature controlled liquid crystal lenses used to fabricate holographic optical elements (HOEs) to attempt achieving better optical performance as well as the results of HOEs fabricated via the refractive lenses. Thermotropic liquid crystals are sensitive to temperature to vary physical parameters such as birefringence, dielectric anisotropy, elastic constants, viscosity, and so on. Therefore, controlling temperature of LC lenses is a possible way to much ideally achieve LC molecular distributions for HOE fabrications.

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The color intelligent vision detection system under the full-color gamut spectrum is invented for human color discrimination. This advanced design has the characteristics of rapid testing time, user-friendly operation, high sensitivity, and accurate detection for color blindness. Its illumination system is equipped with a D65 light source with a power greater than 100 Lux. 16 colorful sets of the optical spectrum regards to the Farnsworth D-15 can be reproduced when the light passes through a designed grating. 8 patients supported by the IRB FJUH110156 program can be evaluated and treated by this innovative instrument.

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Negative photoresist, SU-8, possesses strong/weak shielding effect for DC/AC electric fields. The results can be explained by the electric double layer and resistor–capacitor circuit model. When a DC electric field is applied, LCs in the region coated with (without) SU-8 cannot (can) be rotated by an effective electric field.

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Especially emphasizing in the metaverse, numberous developing techniques related to virtual and augmented reality show significant importance such as holographic optical elements (HOEs). In this paper, HOEs as an optical lens are individually fabricated via single and symmetrically double hole-patterned electrode liquid crystal lenses to investigate and compare optical performance of HOEs.

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Bipolar host compounds should have higher triplet energy than the emitter to ensure exothermic energy transfer. To attain balanced charge transport for phosphorescent OLEDs, we proposed a new series of host materials using phenoxazine or phenothiazine as donors. Three bipolar compounds, POZ-PQ, PTZ-PQ, and POZ-SA, possess good thermal, photophysical, and electrochemical properties, which are suitable to combine with Ir(piq)2acac. The device with POZ-PQ host exhibited higher peak efficiency of 12.9% (8.9 cd/A and 9.2 lm/W). These results indicated that these molecular designs have a high potential for developing bipolar hosts.

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Recently, holographic optical elements (HOEs) have been paid attention to study on applications of virtual and augmented reality due to unique optical capabilities. Such HOEs as lens arrays, they are very suitable to apply in the see-through display applications for augmented reality. In this study, the polarization independent liquid crystal lens (LCL) is considered and used to fabricate HOEs for the purposes of optical improvements due to no optical polarization influence during fabrication processes.

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In this work, we have successfully obtained the optimal LED spectra for the highest TM30 $R_f$ of any CCT. By developing an empirical spectral function to describe the LED spectra with high accuracy and optimizing the empirical spectral function with a specified merit function, the optimal LED spectrum can be easily evaluated. Therefore, a series of the optimal LED spectra for the highest TM30 $R_f$ of various CCTs is concluded.

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Light-emitting electrochemical cells (LECs) have become a trend in the field of electroluminescence research due to their simple device structure. In this study, two pyridium-based thermally activated delayed fluorescence (TADF) emitters, named Pym-CZ and Pym-tBuCZ, were designed and synthesized to obtain high-efficiency orange-red-emitting LECs. The lifetime measurements showed delayed fluorescence at 2887 and 1746 ns, respectively, confirming their TADF characteristics. Notably, the target compounds are the first pure ionic organic TADF materials for orange-red LECs, and the maximal EQE of LEC based on Pym-CZ reaches approximately 1.2%, demonstrating the potential of a new method for manufacturing low-cost orange-red LECs.

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This study prepared isochromatic Phosphor-In-Glass and tried to reduce the thickness. In the study, we successfully produced ultra-thin Phosphor-In-Glass, The sample exhibits excellent optical properties for luminous efficiency up to 118 lm/W and passed the reliability test.

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In this article, the effects of electrohydrodynamic (EHD) and dielectric effects on cholesteric liquid crystals (CLCs) with ion doping are investigated. The states of disturbance and relaxation in Salt-doped cholesteric liquid crystals (SDCLCs) are investigated using the EHD and dielectric effects under different frequencies and applied voltages. From these results, the optical performance of bistable CLCs can be further optimized.

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Abstract: Micro LEDs display is an emerging display. In order to find the optimal membrane stack structure suitable for triple narrow-band-pass filter (TN-PF), three membrane stack structures suitable for narrow-band-pass filter were optimized and analyzed in this study. The simulation results show that the optimal film stack structure is (HL)27 H/Sub, the central wavelength of blue light is 457 nm, the central wavelength of green light is 521 nm, and the central wavelength of red light is 634 nm. The rates were 91.27, 90.71 and 89.39%, respectively.

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The porous structured microcarrier powders were mixed with CQD/PDMS packages to improve the dispersion of QD particles. Results show QDs intensity and PLQY of the containing microcarriers perform the more uniform light filed and slower decline rate under high QD dose conditions.



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A robust method for speckle noise suppression has been proposed by using a bio-inspired scattering device through the nano-casting of polymethyl methacrylate (PMMA) from cicada`s wing. After insertion of bio-inspired device, an obvious reduce of granular pattern has been achived with speckle noise reduction rate of approximately 11.31%. Through the mechanical vibration of scatter by the PZT, a further speckle noise reduction rate around 37.3% was achieved under 5 V applied voltage to produce smoothing laser projection images.

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In this study, we demonstrate a tunable diffraction grating based on a liquid crystal (LC) cell. This cell is sandwiched by two glass substrates in which one substrate is coated with a vertical alignment layer but the other has a dual alignment layer consisting of homogeneous and vertical alignment layers. The dual alignment layer is realized by photo-lithography and lift-off techniques. Such a grating with a small period of 20 μm exhibits a continuous electrical tuning of diffraction efficiency, and thus it has considerable potential for use in photonic applications.

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In this study, only three LED light sources were mixed to obtain the color temperature of the full daylight range from 1800K to 9500K, and all of them had a color rendering index higher than 95. Such a wide color temperature range and high-quality white light can be further applied to smart, health, and human lighting to develop a white light source that satisfies visual comfort and takes into account circadian rhythm effects.

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We investigated the high temperature operation of band-edge lasing from dye-doped cholesteric liquid crystals (DD-CLCs) with rare doping of chiral molecule (ISO-(6OBA)2) into the nematic LC (MDA-981602). As temperature increases from 30 to 90, the DD-CLCs revel an obvious red-shift from 567.5 to 670.6 nm owing to the low anisometric property of chiral molecule. The high temperature operation of band-edge lasing around 3 hrs from our DD-CLC lasers have been demonstrated for the practical applications in near future.

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In this study, the bent dimers were added in the azobenzene chiral doped cholesteric liquid crystals (CLCs). The photoisomerization of azo-chiral material can induce a change in pitch and eventually lead to the occurrence of Helfrich deformation. Experimentally results show that the photoinduced microgrid structure can be largely stabilized by adding bent dimers and simultaneously applying a low voltage below the threshold. Furthermore, the spacing of the resulting meshed microgrids can be tuned by dimer concentration or applied voltage, revealing its potential for multiparameter controllable optical diffractive devices.

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The study in this thesis demonstrates an electrically switchable scattering mode light shutters based on mesoporous silica-doped positive nematic liquid crystals (LCs). The performance of switching between transmitting and scattering states of this LCs scattering light shutters by applying AC field is shown.

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The privacy protected display using a pixel design and broadband quarter-waveplates is reported. Lights exiting pixels in odd and even rows are circularly polarized light with opposite handedness, so the privacy information can only be viewed on the privacy-protected display using a pair of circularly polarized glasses.

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