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Ca₃Y₂Si₃O₁₂:Tm³⁺,Yb³⁺ up-conversion phosphors were synthesized by solid-state reaction method at 1 400 ℃, and the up-conversion luminescence (UCL) properties of the phosphor were studied under 980 nm excitation. The phosphor exhibits strong blue light (475 nm) and near infrared light (810 nm), as well as weak red (650 nm) light, which correspond to ¹G₄→³H₆, ³H₄→³H₆ and ¹G₄→³F₄ transitions of Tm³⁺ ion, respectively. The UCL intensity and brightness of the phosphor increased firstly and then decreased with the increasing Yb³⁺ concentration, and the optimum concentration is 15%. Under the best doping concentration(Yb³⁺mole fraction of 15%), the intensity ratio of blue and red emissions is calculated to be 12:1, and the chromaticity coordinate of the phosphor locates at the blue region (0.129 2,0.152 3). Furthermore, the brightness of the phosphor can reach 6.8 cd/m² as the exciting power density is increased to be 3.9 W/cm². These measurement results indicate that the phosphor exhibits excellent blue UCL property and application potential. The dependence of the UCL intensity on excitation power proves that the observed emissions are obtained via three and two absorption processes. The transition mechanism of the phosphor excited at 980 nm is discussed in detail.

CaYAl_{1-xO4:xMn⁴⁺ red phosphors were prepared by sol-gel method. Differential thermal and thermogravimetric analysis (DSC-TGA), X-ray powder diffraction (XRD), transmission elec-tron microscopy (TEM) and photoluminescence spectrophotometer were utilized to characterize the samples. The effects of the factors, such as synthesis temperature, reaction time and concentration of Mn⁴⁺ on the luminescent properties of the phosphors were studied. The samples give red emissions centered at 660-780 nm under 335 nm excitation, which correspond to ²Eg→⁴A2g transition of Mn⁴⁺. The excitation spectrum monitored by 712 nm consists of two broad excitation bands resulting from ⁴A2g→⁴T1g (335 nm) and ⁴A2g→⁴T2g (475 nm) transition of Mn⁴⁺. The maximum luminescent intensity of CaYAl1-xO4:xMn⁴⁺ phosphors can be obtained with x=0.005 under calcination at 1 200 ℃ for 6 h.}

A new route was developed to synthesize CdSe quantum dots (QDs) in aqueous solution by hydride generation. High quantum yield and stabilized CdSe QDs were prepared by introducing H₂Se gas which was generated on-line by reducing SeO₃^2- with KBH₄ into the aqueous medium containing Cd²⁺ ions. The prepared CdSe QDs were successfully utilized for analysis of Ag⁺ in environmental water samples and cells. The limit of detection is 0.005 μg·mL^-1, and the relative standard deviation is better than 2.7%(n=7). The proposed method retains several unique advantages, including sensitivity, simplicity, stability and environmentally friendly.

The polaron effects on the linear and nonlinear optical absorption coefficients are investigated theoretically for electrons confined in a core-shell quantum dot. The interactions of electrons with the confined longitudinal optical (LO) and the interface optical (IO) phonon modes in the core-shell system are investigated. An analytic formula for the optical absorption is derived with compact-density-matrix approach and iterative method. The optical absorption coefficients in a ZnS/CdSe core-shell quantum dot (QD) are calculated numerically for different pump photon energies, incident optical intensities and relaxation times. Results show that the optical absorption coefficients are dependent on the photon energy and relaxation time dramatically. Moreover, when the electron-LO phonon interaction is considered, the optical absorption coefficient is enhanced more than 2 times.

Ce³⁺, Tb³⁺ co-doped YPO₄ down-conversion phosphors and Er³⁺, Tm³⁺, Yb³⁺ co-doped YPO₄ up-conversion phosphors were synthesized by using hydrothermal method. Uniform-sized (~1 μm) luminescence materials were gained through process optimization. A series of experiments were carried to study the effect of reaction temperature, time, annealing temperature and doping ratio of rare-earth ions on luminescence properties. The down-conversion luminescence nano-material YPO₄:Ce³⁺,1%Tb³⁺ emits strong green light excited by 295 nm ultraviolet light,and the up-conversion nano-material YPO₄:3%Er³⁺,Tm³⁺,Yb³⁺ emits warm white light excited by 980 nm infrared light, respectively.

Zn_1-xCu_xO films were fabricated on FTO substrates by electrophoretic deposition. The microstructure, PL spectra, I-V characteristics, retention measurement and switching voltage distribution were investigated. PL spectra indicate that Cu doping introduces deep acceptor level in the bandgap and decreases the concentration of oxygen vacancy, which result in the decreasing intensity of ultraviolet, blue and green luminescence. The deposited films are dense and uniform, and exhibit bipolar resistive switching behaviors with a high OFF/ON ratio of 10⁵. The resistive switching behaviors are governed by Ohm's law in the LRS and space charge limited conduction (SCLC) in the HRS, respectively. Good endurance characteristics can be retained after 100 switching cycles without any obvious fluctuation in R_off/R_on ratio. Cu²⁺ doping has little influence on low resistance state (LRS), but decreases the dispersion in high resistance state (HRS) and switching voltage V_SET. When Cu doping content x=0.04, the devices show good properties: R_off≈10⁶ Ω, R_off/R_on≈10⁴,and the value of V_SET is 0.4-3.03 V.

We report the incorporation of lithium fluoride doped 4,7-diphenyl-1,10-phenanthroline (Bphen LiF), Al, and molybdenum trioxide (MoO₃) which is utilized to form the charge injection buffer layer in single-unit organic light-emitting devices (OLEDs). This hybrid buffer layer at the anode/organic interface was found to be very effective, which increased accumulation of holes at the NPB-buffer interface to improve the balance of the carrier injection. Both the maximum current efficiency and maximum power efficiency of the device were improved by 1.3 times. The results strongly indicate that carrier injection ability and balance shows a key significance in device performance.

High-quality Ga₂O₃ films were grown on the c-plane sapphire substrates by metal organic chemical vapor deposition and annealed in the different atmospheres consisting of vacuum, oxygen, nitrogen for 30 min, respectively. The effects of annealing on crystal structure and optical properties of β-Ga₂O₃ film were researched. The results show that all anneal methods can optimize the crystal structure and optical properties of β-Ga₂O₃ films. Especially, the transmittance and surface roughness of the film annealed in the oxygen reaches 83% and 0.564 nm separately compared with other annealed films, and its absorbtion edge gets sharper. It reveals that the oxygen anneal has more important effect on the improvement of the crystal quality. The films annealed in nitrogen and vacuum both exhibit an clear emission peak at 365 nm in the PL spectra.

The electrical bistable devices based on poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV)/tris(2-phenylpyridine)iridium(Ⅲ) films were fabricated by using the spin-coating method. The devices with different concentrations of MEH-PPV were studied. All the devices have the typical bistability. When the concentration of MEH-PPV is 4 mg/mL, the device has the electrical ON/OFF ratio of about 1×10³. In addition, the current-recycle measurements were taken to investigate the sustained stability performance of the device. The performance of the device remains stable after 10⁴ recycles. The fitting of I-V characteristics was utilized to analyze the charge transport process with the help of the diagram of the energy bands of the device. The results show that the current transition process is attributed to the formation and damage of the interface dipole layer under different voltage biases.

Piezoelectric printing is one of the main processes of printed electronics. In this process, piezoelectric waveform has a direct impact on the spray regime of ink droplets, which will play an important role in the devices printing. In this text, effect of piezoelectric waveform on printing thin film transistor(TFT) electrode was studied. By changing slew rate and duration, the piezoelectric waveform parameters, a series of printing samples were obtained, and their patterning quality and surface roughness were measured. With the increasing of the slew rate and duration, the kinetic energy of the ink droplet increases, the patterning quality improves first and then deteriorates, and the surface roughness of final printing pattern gets higher. TFT electrodes with fine pattern are fabricated when the slew rate is from 0.08 V/μs to 1.65 V/μs, and the duration is from 1.216 μs to 2.688 μs. Fine-patterned TFT electrodes with surface roughness of 59.04 nm and 59.27 nm are fabricated when the slew rate and duration are 0.25 V/μs,2.688 μs and 0.65 V/μs, 1.600 μs, respectively. By adjusting the parameters of piezoelectric waveform, the optimization of printing quality can be achieved.

Three-level system-based rate equation and power transfer equation were used to solve the temperature dependent emission spectral properties for 3.3 nm PbSe quantum dot doped liquid core fiber under different fiber length and doping concentration, considering the effect of the temperature on the parameters.It is found that the spectral peak position shifts to the red in a similar red shift rate with the temperature increasing, in the case of different fiber length. For the longer fiber, the spectral peak intensity decreases in a larger decline rate. In the case of different doping concentration, with the temperature increasing, the spectral peak position shifts to the red in a similar red shift rate, and the spectral peak intensity decreases in a similar decline rate.

In order to realize Q-switched fiber laser with high energy pulse, passively Q-switched Yb³⁺-doped fiber laser based on the microfiber-single wall carbon nanotube (SWCNT) saturable absorber (SA) was reported. The microfiber was fabricated by drawing the single mode silica fiber and then composite with the SWCNT solution, further on preparation of all fiber integrated devices. By inserting the SA in a Yb³⁺-doped fiber laser ring cavity pumped by a 976 nm laser diode, stable passively Q-switched pulse train occurs at 53 mW incident pump power. Increasing the pump power to 76 mW, 3.1 μs pulses at 1 039 nm with a repetition rate of 25.5 kHz are obtained, which corresponds to single pulse energy of 941 nJ. This result shows that the microfiber based SA can enhance the threshold of material damage and obtain high energy pulse laser.

In order to stabilize the coupling efficiency of the laser beam from the semiconductor laser through optical fiber, a laser with groove structure was proposed, and the laser beam, coupling efficiency and P-I characteristics were researched. The periodic grooves in the ridge region of the laser were etched to improve the gain distribution in the active region of the laser. The laser beams of the common laser and the groove structure laser were analyzed, the coupling efficiency and P-I characteristics were tested. The results show that the strip laser with groove structure can stabilize the cavity mode, avoid the "Kink" effect and improve the coupling efficiency to 97.7%. The laser with groove structure can solve the phenomenon of optical filaments fluctuation effectively and improve the stability coupling efficiency of the beam.

A system based on CCD to measure laser beam quality was designed and built. CCD was used to measure laser beam diameter at different locations. The collected data samples were then curve fitted to the beam propagation hyperbolic equation. Here the non-linear least squares method was employed to fit the hyperbolic curve, and the results of the fitting procedure yielded laser beam quality M². To prove the accuracy and reliability of this self-made device, a comparison was made between the measurement results of this device and the specialized instrument M² equipment, which showed a very good coherence. It indicates that this experiment device can replace M² equipment.

The smile effect caused by thermal stress is a common problem in high power semiconductor laser array packaging. The mechanism of smile effect caused by packaging thermal stress was studied firstly. Then two measures, the differential temperature soldering technique and the prestressing force technique, were putted forward. The feasibility and effectiveness of the above mentioned techniques, were studied through the simulation method for an 808 nm semiconductor laser diode array. Using the traditional soldering technique, the smile effect is about 39.36 μm at 22 ℃. Using the differential temperature soldering technique, increasing the chip's temperature to 429 ℃ before soldering can reduce the smile effect to 1.9 μm. Using the prestressing force technique, applying a tensile force of 190 N along the long axis direction on each side of the heat sink can reduce the smile effect to 0.35 μm. Both techniques are proved to be effective. The two techniques are easy to implement, and the prestressing force technique can be used to adjust or modify various smile effect types and different smile values.

In order to develop rapid and non-destructive method for identification of laser printer toner, six kinds of black toner were identified rapidly by combining hyperspectral imaging technique and five kinds of statistical learning method. Method: a visible and near-infrared hyperspectral imaging system covering the spectral range of 400-1 000 nm was set up to capture hyperspectral images of toner samples. Savitzky Golay smooth, normalize, multiple scatter correction and standard normal varite were applied as preprocessing method. After that, five statistical learning methods, including Random Forest (RF), K-nearest Neighbor (KNN), Support Vector Machine (SVM), Partial Least Square-discriminant analysis (PLS-DA) and Soft Independent Modeling of Class Analogy (SIMCA) were applied to establishment of discriminant models based on the full spectra. The properties of discriminant models were compared and valued by three parameters, precision, false reject rate (FRR) and false accept rate (FAR). Result: Among all discriminant models, the SVM and PLS-DA model show the best identification result, the precision is 100%, FRR and FAR are both 0. Conclusion: black toner could be identified by visible and near-infrared hyperspectral imaging technique combined with statistical learning method rapidly.

In order to solve the problem that the ambient light and color temperature have a great influence on the image color reproduction of LCD monitor, an image color consistency method based on the spectral characteristics of LCD monitor was proposed. The spectra were of 99 industry-recognized color measured at different ambient light and color temperature, and the spectral color reproduction law of LCD monitor image under different ambient light and color temperature was summarized. Using the spectra superposition under different ambient light and the corresponding law of different color temperature, LCD monitor image color consistency can be achieved under different ambient light and color temperature. The average subjective evaluation Z score of image is 0.50. The results indicate that this method can well solve the LCD monitor image color consistency under different ambient light and color temperature.

In order to study the synthesis mechanism of noble metal nanoclusters and the application of noble metal nanoclusters-electrochemical sensors, some methods of the synthesis and the properties of noble metal nanoclusters are described and compared. The principle and characteristics of electrogenerated chemiluminescence (ECL) are briefly described, the progress of application of noble metal nanoclusters-electrochemical sensor in life analysis and the related research of our research group are mainly introduced. The development and application are prospected, which may provide a reference for the research of noble metal nanoclusters-electrochemiluminescent sensor in life analysis.

Compared with the fruit with thin skin, it is more difficult to acquire the internal quality information of fruits with thick skin. In this study,the hyperspectral diffuse transmission technique was used to visually analyze the soluble solids content (SSC) of navel orange. By comparison of the results, the model using the spectra pretreated by baseline correction as the input was the best one. Based on the baseline corrected spectra, successive projections algorithm (SPA) was applied to select feature wavelengths and finally 9 bands were remained. The results of the partial least squares regression (PLSR) model for SSC prediction indicate that the correlation coefficient of calibration (r_cal) is 0.891, the root mean square error of calibration (RSMEC) is 0.612, the correlation coefficient of prediction (r_pre) is 0.889, and the root mean square error of prediction (RMSEP) is 0.630, respectively. Using the spectra of feature wavelengths as the input, the multiple linear regression (MLR) models for SSC prediction were calibrated. Based on the MLR model, each pixel value of the images was calculated. Combined with the image processing, the distribution maps of SSC in navel orange were drawn. So, the SSC of navel orange can be intuitive judged.