Session Index

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In this study, we developed NiOx decorated p-n junction GaN photoanodes for overall water splitting. The surface p-n junction enhances the charge separation and the NiOx nanoparticles catalyst reduced the interfacial charge transfer resistance. As a result, the NiOx/p-n-GaN photoanodes exhibited a photocurrent of 0.2 mA cm-2 at zero bias.

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Radio-frequency (RF) magnetron sputtering is used to prepare Germanium-tin (GeSn) alloy in this work. The crystallization, electrical conductivity, and absorbance were measured by X-ray diffraction, Raman scattering, transmission line resistance, and optical transmittance. After annealing at 450℃ for 60 minutes, the GeSn layers exhibit (111) preferred orientation, with a small grain size of 2.5 nm. By electron dispersive spectroscopy (EDS), the amount of Sn is approximately 3%. The carrier concentration for this film is 2.62E+19 cm-3 and the mobility is 18.52 cm2/Vs.

 

We propose an electric field intensity sensor by using a fiber Bragg grating (FBG) packaging within liquid crystals. Two different processes of FBG include the fiber side-polishing and taper etching for improving the sensitivity.

 

A magnetic field sensor based on a tilted fiber Bragg grating (TFBG) combined with the magnetic fluid is proposed. By changing the magnetic field perpendicular to the TFBG axis, the wavelength of the cladding modes is shifted. For the magnetic field in the range from 0 to 60 Gauss, the maximum sensitivity of -0.586725pm/Gauss is obtained.

 

This paper proposed a magnetic field fiber sensor based on fiber Bragg gratings (FBGs) combined with the magnetic fluid (MF). Two different fiber structures are designed for measuring the testing magnetic field by changing the index change of magnetic fluid and then to cause the variation of grating reflection spectrum.

 

We proposed a novel sensor based on an ultracompact leaky-guided liquid-core fiber Mach-Zehnder interferometer (LLCFMZI) for high modulation of interference spectra. The structure is based on a micron-sized hollow-core fiber (HCF) splicing a tilt endface single-mode fiber (SMF) to create a miniature oblique gap for effective access of different liquids.

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This study presents a highly sensitive liquid-core fiber Michelson interferometer (LCFMI) for sensing temperature (T). The structure is based on single-mode fiber (SMF) fusion splicing a micron-sized liquid-core fiber (LCF) whose volume of liquid is only a few picoliters.

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This paper shows the fiber grating sensor for detecting acoustic vibration signals. We design two kinds of sensing structures and experimentally demonstrate to confirm the sensing performance in different frequency bands. The wavelet transform is used for analyzing the variety of the non-stationary signal.

 

This paper proposed a novel electric-field fiber sensor composed of a tilted fiber grating (TFBG) and the liquid crystal. Due to that TFBG is insensitive to electric field changes, the index change of TFBG’s cladding layer can be used for indirectly measuring the testing electric field. The variation of the electric-field intensity will create the index change of the liquid crystal and then to cause the loss-dip wavelength shift of the TFBG. By means of monitoring the wavelength shift of spectrum loss-dip to obtain the the testing electric field intensity.

 

In this paper we propose a humidity fiber sensor by using a tapered superstructure fiber grating coated on the thin-film of calcium chloride. The operation mechanism is based on the humidity to cause the index change of calcium chloride and then to result in the grating spectrum variation.

 

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Doping chromium inside ReSe2, creates different carrier types of crystals, p-type (Cr10% and 20%) and n-type (Cr0%, 1%, and 5%) multilayer ReSe2. The band level predicted by temperature-dependent resistivity infers that Cr3+ (p-type) is trapped in the shallow level while Cr6+ is found in the deep level carrying n-type donor. The p-n diode, for the first time, is constructed by stacking multilayer of ReSe2 (n-type) and ReSe2: Cr 20% (p-type) in the microscale layer. Under illumination, E//b-axis polarization photovoltaic cell response exhibits the highest energy conversion efficiency and promisingly contributes to solar cell devices in 2D semiconductor.

 

In this work, zinc oxide (ZnO) films were deposited on PC61BM electron transport layer by thermal evaporator as an interface layer for perovskite solar cells. Using ZnO films could reduce the defects on PC61BM surface and make more matching energy level which could improve the performance of perovskite solar cells.

 

In this study, the efficiency enhancement of InGaP/GaAs/Ge solar cell was demonstrated using an TiO2/Al2O3 double-layer anti-reflection coating with (and without) various diameters of indium nanoparticles (In-NPs) embedded in TiO2 layer. The best increasing in efficiency of 17.06% was obtained by using the In-NPs of 23 nm in diameter.

 

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The pulse-wave modulation plasma with CO2/SiH4 gas flow ratio were used to separately deposit a 100 nm thick high energy gap (Eg) a-SiOx:H (C layer) film, a low Eg a-SiOy:H (A layer) film or a C/A superlattice (a-SiOx:H/a-SiOy:H) film at p/i or i/n interface of a p-i(a-Si:H)-n reference cell. The influence of C, A and C/A superlattice thin films at the p/i and i/n interfaces on the electric properties of p-i-n solar cells were investigated.

 

Pulse-wave modulation plasma with change the CO2/SiH4 gas ratio and RF power was used to fabricate and control the structural and optical properties of i-a-SiOx:H intrinsic passivation layer for HIT solar cells. The effects of single i-a-Si:H or i-a-SiOx:H layer, and dual i1-a-SiOx:H/i2-a-Si:H passivation layers on the performance of HIT solar cells were investigated.

 

We propose an open-cavity Mach-Zehnder interferometer by splicing a photonic crystal fiber (PCF) with a polished pencil-shape single-mode fiber (SMF). It is shown that the gas indeed can be filled into the open cavity successfully, and the measured pressure sensitivity is -67.86pm/psi.

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The guided mode of NC-HCPCF with different core diameters, the thickness, and numbers of capillaries for capillary cladding designs by simulation are presented. The proper number of negative curvature ratios enhances the fundamental mode power and the 8-capillary cladding of NC-HCPCF is better than 5- to 7-capillary for transmission power.

 

To improve the parasitic absorption problem, we tried to change the wide band gap material molybdenum oxide (MoOx) to the silicon heterojunction (SHJ) solar cell structure, thereby replacing the a-Si in the p-type doped amorphous silicon a-Si:H(p) of the layer. We compared the optical properties of MoO¬x with different thickness settings, and proved that MoOx has good carrier transport effect by changing the metal electrode at 180°C hot plate annealing temperatures. Preliminary results show that the Si HJT cell with a 15 nm-thick MoOx layer achieves a power conversion efficiency (PCE) of 21.2% and an open-circuit voltage (Voc) of 640.6mV.

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There is a fundamental trade-off between the resolution and the field of view in traditional imaging systems. Recently, Fourier ptychography (FP) based image reconstruction has shown excellent capability to produce sub-micron resolution images from wide field microscope without any moving parts. In this work, we demonstrate the possibility of generating high-resolution microscopic images using cost-effective consumer parts. The imaging system consists of an evolution board of raspberry Pi4, LED array module and a 5-mega pixels camera. By using FP to reconstruct the captured image at different angles, we demonstrate transforming low-resolution images to high-resolution giga-pixel images with large field-of-view.

 

In this work, we propose an electron-selective buffer layer (ES-BL) in fullerene-based organic photovoltaics (OPVs) by blending fullerene (C60) with a tris(8-hydroxyquinoline)aluminum(III) (Alq3). Compared to neat Alq3 for exciton blocking purposes, the proposed Alq3:C60 buffer layer shows higher power conversion efficiency (PCE) of 1.15%. In addition, insignificant PCE loss is observed after more than 1 day of continuous operation under AM1.5G solar illumination at 100 mW/cm2 by replacing BCP (τ84 ~25 hours) with Alq3:C60 buffer layer (τ98 ~25 hours). This can be attributed to the suppression of C60 photo-oligomerization process by the robust Alq3 molecule.

 

In this work, we propose a charge carrier selective structure by inserting an electron-transporting material (Bathophenanthroline; BPhen) between MoOx and the photoactive blend. The device shows an improved hole extraction process with a 10% enhancement of Jsc. In addition, the device shows an extended operational lifetime of 160 hours after 10% decay of the initial PCE, which is much durable compared to the one using standard MoOx neat film as hole extraction layer.

 

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the composition and chemical states of films in semiconductor industry. The purpose of adding Al2O3 passivation layer is to facilitate carrier lifetime and passivate intrinsic defects of photovoltaics. In this study, TEM was used to confirm the thickness of Al2O3 layer and SiOx interlayer formed by different annealing temperatures. To verify the chemical state of SiOx layer, XPS combined with Ar+ sputtering was used to reconstruct the elemental distribution of Si/SiOx/Al2O3 samples in different depths. The results show that the thickness of the SiOx layer is increasing with higher annealing temperature.

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This study proposed a chemical-modified polymer air-gap fiber Fabry–Pérot interferometer (PAGFFPI) with coating an Ag-film by silver mirror reaction (SMR) for achieving hot-wire anemometry (HWA). Experimental results demonstrate that the sensor can be effectively heated by LD with high responses and good sensitivity.

 

A new vertical structure LED is proposed recently to solve the uneven current spreading density problem of Y-shaped vertical structure LED. In this paper, we investigate current density and near-field light intensity distribution of the Y-shaped and the new vertical structure LED at different wavelengths. Five wavelengths are chosen for comparison: deep ultraviolet light (365nm~375nm), ultraviolet light (380nm~400nm), violet light (420nm~430nm), blue light (440nm~460nm), and green light (520nm~530nm). We find that the current distributions are distinct for different wavelengths. The new structure exhibits superior current spreading and light emitting uniformity at all wavelengths.

 

Organic-inorganic hybrid perovskites have become one of the most promising photoelectric materials for generating solar cells in recent years. However, their instability to environment remains a tough issue. Thermal degradation is one of the most important problems hindering their commercialization. This study investigates three kinds of perovskite films (MAPbI3, MAPbI3-xBrx, MAPbI3-xClx), conducting thermal induced stability experiments. Several surface analysis techniques, such as X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometer (TOF-SIMS) are used to provide a deeper understanding into materials decomposition. In summary, it is found that bromine-doped perovskite films have better stability upon exposure to heat.

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By finite-difference time-domain (FDTD) simulations, we design tungsten absorber for Solar Thermophotovoltaics (STPV) system. In this study, periodic pyramid structures with Tungsten material modeled by complex-conjugate multiple-pole model and convolutional
perfectly matched layers (CPML) are adapted to simulate the optimal structure with almost unity absorptivity in solar spectrum region.

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In this study, perovskite solar cells (PSCs) based on three different annealing temperatures are fabricated in a low humidity glove box by using two-step method. With the improvement of surface morphology and crystallinity of perovskite layer, an optimal photoelectric conversion efficiency (PCE) of 12.19 % is achieved.

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This paper proposed a tire pressure sensor based on fiber Bragg grating (FBG). The operating mechanism is that the tire pressure squeezes the polymer of sensor to stretch the grating and to cause the grating center wavelength to be shifted. By changing the size of the pressure-receiving opening, the sensitivity can be improved.

 

We proposed a hydrophone based on a fiber Bragg grating for detecting acoustic-wave signals of underwater. The hydrophone consists of fiber Bragg grating, silicon thin-film, and 3D print structure.

 

In this article, we proposed the novel human-pulse fiber sensors with the plane type and side-pressure packaging type for the diagnosis of human-pulse. The affordable and compact structure shows that it can be applied for detecting human pulse signals.

 

In this article, we proposed and simulated a Silicon core fiber incorporated with a fused silica grating shaped design. The simulation results show this design could be applied for detecting temperature and refractive index simultaneously, and sensitivity were up to 1.6 nm/oC and 1.733 µm/RIU, respectively.

 

In this study, NiOx thin film was prepared by the solution-combustion process at 250 °C, a temperature lower than the actual reaction temperature. The maximum power conversion efficiency of inverted perovskite solar cells made with pristine NiOx and 5% Zn-NiOx as the HTL was 13.62% and 14.87%, respectively.

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The perovskite quantum dot QD-CsPbI3 was synthesized by the hot injection
method. The perovskite film can be processed with quantum dot to make the better film
crystallinity. By applying the QD-CsPbI3, the reduction of the
Cs0.05FA0.81MA0.14PbBr0.14I2.86 perovskite film interface defects improved the efficiency of
solar cells.

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In this study, the pseudohalide perovskite in 2D/3D hybrid perovskite films were made by the low-pressure vapor-assisted solution process (LP-VASP). Using the excessive PEAI doped in the precursor, and the halogen replaced I ions replaced with SCN ions. It was found that SCN ions can inhibit the appetite growth of 3D perovskite and existed in the bottom of perovskite film.

 

We devise a different doping ratio of the cesium chloride and formamidinium iodide on FAPbI3. Cesium (Cs) can stabilize the α phase of perovskite. Consequently, the best power conversion efficiency of perovskite solar cells has increased from 14.6% to 18.9%.

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This study used an femtosecond laser machining system developed two types of fiber-optic interferometers with a sensing function. The refractive index sensor sensitivity of the fiber-optic Mach-Zehnder interferometer was 35.1nm/RIU. The fiber-optic Fabry-Perot interferometer of two microholes only take 0.005 s that is much faster than that by one microhole on the hollow code fiber, and has the potential capability for on-site, in-vivo, and remote sensing, and has the potential use for disposable sensors.

 

In this research, influence of the reaction time of MAI and PbI2 for forming the perovskite crystals to the current density of perovskite solar cells (PSCs) is analyzed. Next, the mesoporous layer is modified with Au@SiO2 of 42.33 nm, the PCE is further increased from 14.11 % to 16.50 %.

 

The nanoporous nickel oxide (NiOx) layer as well as NiOx thin film was prepared via chemical bath deposition as the hole transport layer (HTL) in inverted perovskite solar cells (PSCs). The sponge-like structure of the nanoporous NiOx helps to grow pinhole-free perovskite film with larger grain size compare to the NiOx thin film. The inverted PSCs based on the nanoporous NiOx layer showed the highest efficiency of 13.43% and negligible hysteresis that was better than the one using the NiOx thin film as the HTL. Moreover, the PSCs sustained 80% of their initial efficiency after 50 days storage.

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Perovskite solar cells (PSCs) with inverted structure generally present higher stability and negligible hysteresis effect. One of the most important parts of the inverted photovoltaic is the hole transporting layer (HTL). In this study, we choose metal doped NiOx as HTL material and synthesized it by nanoparticles method, which does not need anneal process. Moreover, NiOx nanoparticles does not react with perovskite layer and the energy level alignment of NiOx thin film is more favorable with active-layer. In this report, NiOx based PSCs with optimized metal doping ratio has reached 14.33% conversion efficiency as compared to 12.59% without metal doping.

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All inorganic perovskite has developed as a candidate for photovoltaic application due to its decent thermal stability. Nevertheless, the ion migration remains an issue due to the instability of mixed halide perovskite under illumination with the presence of phase segregation. Here we present a technique to investigate the light-induced ion migration within the CsPbIBr2: Probe and Set operation. By tuning the power and the duration of the laser illumination, we visualize the phase segregation and its reversal via photoluminescence measurement.

 

Tungsten disulfide (WS2) and graphene are two-dimensional (2D) materials of typical features. They process the ability to modulate and communicate signals between electronics and photonics in an extreme lateral dimension. However, the characteristics of primitive graphene photodetector has weak photo responsivity. In this research, via the WS-2/graphene heterostructures to induce more electrons by internal electric fields and achieve the high photoresponsivity (~5.7A/W). Finally, the correlation between photoluminescence (PL) and photocurrent is analyzed.

 

In this study, we investigated the effect of annealing temperature on NiOx thin films prepared through sol-gel processing from two nickel precursors: nickel acetate tetrahydrate and nickel acetylacetonate. The results showed that the NiOx films annealed at 400 °C exhibited the best electrode properties and achieved the highest device efficiency.

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