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In order to enhance upconversion luminescence of β-NaGdF₄:Yb³⁺, Tm³⁺ nanocrystals and meanwhile overcome the particle size enlargement caused by epitaxial growth technique, NaGdF₄:Yb³⁺, Tm³⁺@NaGdF₄ core-shell nanostructure was prepared using cation exchange strategy. The upconversion luminescence of the core-shell nanocrystals was investigated under 980 nm laser excitation. The oleate-capped β-NaGdF₄:Yb³⁺, Tm³⁺ nanocrystals with diameter about 10 nm were firstly prepared by thermal decomposition procedure. Then, the cation exchange reaction of the nanocrystals with Gd³⁺ was performed in l-octadecene and oleic acid mixture solution at 300℃. Experimental results show that the cation exchange strategy has significantly enhanced upconversion luminescence brightness of the nanocrystals, which attribute to the suppression of inner Yb³⁺ de-excitation by the cation exchange shell and the enhancement of energy transfer from Yb³⁺ (²F₅) to Tm³⁺ (³H₅, ³F_2,3) inside of the nanocrystals. The maximum improvement of NIR emission for Tm^{3+ 3}H₄→³H₆ transition is achieved with 6.5 times than that of the contrast sample after 30 min of exchange reaction. It demonstrates that the cation exchange strategy can not only enhance NIR luminescence of the nanocrystals, but also well retain small particle size. It provides a simple and convenient way to development of high brightness upconversion nanocrystas with comparable in size to biomolecules, which has enormous applications in biomedical imaging fields.

β-Ga₂O₃ nanowires (NWs) and nanoribbons (NBs) were synthesized under different gas flow rates via chemical vapor deposition (CVD) method. The results show that the NWs and NBs are monoclinic structure. NWs has higher crystal quality than NBs. The cathode luminescence (CL) spectra show that the NWs and NBs have strong UV-blue emission band. By comparing the CL spectra of the NWs and NBs, it is found that the UV and blue luminescence of β-Ga₂O₃ NWs and NBs located at 374 and 459 nm, mainly due to radiative recombination emission of oxygen vacancies (V_O(Ⅰ) and V_O(Ⅱ)).

Water-soluble fluorescence zinc oxide quantum dots (ZnO-QDs) and carbon quantum dots (C-QDs) were prepared by sol-gel and hydrothermal method, and their quantum yields were 38% and 61%, respectively. ZnO and carbon quantum dots mixtures (ZnO/C-QDs) were prepared based on the as-prepared ZnO-QDs and C-QDs, and their optical properties were investigated, respectively. The transmission electron microscopy (TEM) images indicate that the size of ZnO-QDs and C-QDs are around 3-6 nm and disperse uniformly. The photoluminescence (PL) spectra of ZnO-QDs and C-QDs dominate by a broad emission centered at around 540 nm and 450 nm, and their optimal excitation wavelengths are 370 nm and 350 nm. By adjusting the volume ratio between ZnO-QDs and C-QDs, the spectra of as-prepared ZnO/C-QDs show continuously variable properties, and white fluorescence can be observed from the ZnO/C-QDs.

CaAlSiN₃:Eu²⁺ red phosphors were synthesized through nitrating process under atmospheric pressure with Ca_xSi alloy as precursor and EuB₆ powder as activator. The influences of different sintering temperature, fluxing agent and secondary sintering on the characteristics of morphology, crystalline structure, luminescent properties and thermal stability of CaAlSiN₃:Eu²⁺ red phosphors were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and fluorescence spectrophotometer. It displays that the nitride synthetic has CaAlSiN₃ structure with space group Cmc2₁, and its optimum sintering temperature is 1550℃. The performance of its luminous intensity was significantly enhanced when the mass fraction of SrF₂ flux was 6%. In the secondary sintering, the relative intensity of emission spectrum was nearly doubled, the grain size was optimized, and the relative intensity of the emission spectrum was also improved. Appling Ca_0.98AlSiN₃:0.02Eu²⁺ red phosphor with 640 nm emission wavelength in white LED packaging, the devices with high color rendering index of 92.5 and 95.8, corresponding color temperature of 3109 K and 4989 K were obtained, respectively. The results indicate that the white LED emitting devices with high rendering index of positive white and warm white can be achieved by applying nitride synthetic.

The smile effect was measured in the process of semiconductor laser packaging using the external cavity mirror of which the reflectance was greater than the front cavity surface of the semiconductor to form external cavity semiconductor laser. In measurement, the cylindrical lens was inserted in the external cavity. The external laser cavity was only formed between the outer mirror and the single light emitting point in the cylindrical lens light axis. The laser threshold of the light emitting point was reduced to output laser under the excitation current less than the normal threshold value. The light emitting point of the diode laser was selected one by one by moving the cylinder lens, so the smile effect was measured by summarizing all beam position. The low current is no harmful effects on the diode laser bar, and the influence of the other emitters on CCD is avoided by measuring single emitter.

1-D ZnO nanorods arrays were fabricated on the wet etched GaN substrates and the microstructure and optical properties were studied. Compared with ZnO nanorods grown on GaN with no corrosion and corrosion for 5 min and 10 min, the nanorod arrays with the etching time of 8 min are the finest and have the best optical properties, besides its corresponding PL spectral peak integral ratio I_UV/I_vis is the largest. Because the dislocations in the GaN substrate with the etching time of 8 min are almost entirely in the surface outcrops, and the ZnO nanorods grown on it are easy to attach to form more nucleated seeds, furthermore it is helpful to induce the helical growth of ZnO crystals when the dislocations of the substrate are at the edge of the surface. Therefore, the ZnO nanorods are more compact and uniform, and the crystal quality and optical properties are more ideal.

Asymmetric structures were designed and fabricated featured with differential surface curvature across the microscale profiles and the characteristic anisotropic gradient. TIPS-pentacene was deposited over the profile via a solution precursor and directional crystallization is achieved owing to the asymmetric surface energy distribution across the surface of the liquid. With the semiconductor layer printed via this method, the average mobility of an arrayed organic thin-film transistors (OTFTs) was increased by 40% while the coefficient of variation (CV) was reduced from 68% to 39%.

The transient electroluminescence response characteristics at different temperatures and the current density-voltage-luminance (J-V-L) characteristics of several organic light-emitting devices (OLEDs) were studied. It is found that the acceleration of the turn-on voltage decreasing with the increase of temperature appears the inflection point at 200 K, and this value mainly depends on the mobility of the electron transport layer Alq₃. When the temperature is 200 K, the most important factors of delay time t_d is hole injection barrier MoO₃. The t_d decreases with the increase of temperature and gradually disappears at 300 K. V_f represents the average rate of the fall time increasing with the temperature. Both MoO₃ and Ir(ppy)₃ can promote the accumulation of carriers. ΔV_f caused by MoO₃ injection layer is 0.52 μs/K, and that caused by the electroluminescent material Ir(ppy)₃ is 0.73 μs/K.

The spectral response and dark current of p-i-n type and Schottky barrier GaN-based ultraviolet detectors are investigated. It is found that the responsivity of p-i-n detectors decreases with increasing thickness of p-GaN layer in p-i-n structure detectors, and the downward trend of responsivity is more pronounced at shorter wavelength of incident light. The responsivity of the Schottky barrier detector is obviously higher than that of the p-i-n structure, mainly because a lot of incident photons are absorpted in the p-GaN layer. The dark current of Schottky barrier ultraviolet detectors is far larger than the p-i-n ultraviolet detectors, and the results are basically consistent with the simulations, mainly because the Schottky detectors are majority carrier devices, and p-i-n detectors are minority carrier devices. To fabricate high performance GaN ultraviolet detectors, it is better to employ p-i-n structure with very thin p-GaN layer.

Transparent conductive film MoO₃/Au/MoO₃ was used as the anode of organic solar cells (OSCs) instead of indium tin oxide (ITO). A series of MoO₃/Au/MoO₃ transparent electrodes and OSCs with the structure of MoO₃(y nm)/Au(x nm)/MoO₃(y nm)/CuPc(25 nm)/C₆₀(40 nm)/BCP(8 nm)/Al(100 nm) were fabricated. The results show that the photoelectric characteristics of MoO₃/Au/MoO₃ electrode can be controlled by changing the film thickness of each layer, the optimum performance of OSC is achieved when the thickness of MoO₃ film is 40 nm and the thickness of Au film is 10 nm. Besides, the performance of the OSC with MoO₃/Au/MoO₃ electrode is close to that of OSC with ITO electrode.

Cu₂ZnSnS₄ thin films with different Cd compositions were prepared using sputtering-sulfuration method. The best device with efficiency as high as 10.65% was achieved. The scanning electron microscope, temperature dependent photoluminescence, excitation power dependent photoluminescence were employed to character the materials and the capacitance-voltage and current-voltage characteristics of the solar cells were studied. It is revealed that the photoluminescence of Cd doped Cu₂ZnSnS₄ is dominated by donor-acceptor pairs, with carriers showing strong localization. Cd incorporation is found to be beneficial in removing deep defects and reduce the energy shift between the emission peak and absorption edge, resulting in the reduction of the open circuit voltage loss of the solar cell device. These findings are helpful to make further improvement in device efficiency.

The inverted organic solar cells with ZnPc(OC₈H₁₇OPyCH₃I)₈ film as cathode buffer layer and P3HT:PCBM as active layer were fabricated. The cathode buffer layers were treated by the solvent vapor and airflow annealing to investigate the effect of the annealing treatment methods on the device performance. The results indicate that the annealing treatment can effectively improve the morphology of the buffer layers. The power conversion efficiency(PCE) of the solar cell is improved from 2.14% to 3.76%, the current intensity(J_sc) increases from 8.12 mA/cm² to 10.71 mA/cm², and the fill factor(FF) is improved from 0.45 to 0.61 for the annealing process. More importantly, the stability of the device is enhanced, with the device life being 1.4 times that of the conventional device. This simple cathode interface treatment method provides an effective way to improve the performance of polymer solar cells.

A novel fluorescence nanosensor for Bi(Ⅲ) ions determination was developed based on the fluorescence resonance energy transfer from semiconducting polymer dots to methylene blue. The methylene blue attached to semiconducting polymer dots by electrostatic interaction, leading to fluorescence quenching of the fluorophores. When Bi ion was added, it coordinated more strongly with the carboxyl-functionalized semiconducting polymer dots than methylene blue, which made the methylene blue detached from semiconducting polymer dots and interrupted luminescence energy transfer, allowing recovery of fluorescence. Such fluorescence responses can be used for well quantifying Bi ions in the range of 0-0.5 μmol/L with a 16 nmol/L detection limit. The proposed sensing system has been successfully used for the assay of Bi ions in lake water.

Schiff base was synthesized by the reaction of oligochitosan with furfuraldehyde, and acted it as ligand to prepare different molar Schiff base copper complexes which possessed electrochemical activity. The action mechanism of the complex and DNA was studied by spectrometry, viscosity measurement, cyclic voltammeiry and melting point experiment. The results indicate that the reaction of central Cu²⁺ at glassy carbon electrodes is controlled by diffusion process mechanism. The intensity of the maximal absorption peaks of the complexes is weakened with the increasing of DNA concentration, and the oxidation peak current is decreased but no new redox peak appeared. At the same time, the viscosity and melting point of DNA are increased. There are intercalation action between the complex and DNA, and DNA-binding ability order is FCOS-Cu11 >FCOS-Cu13 >FCOS-Cu31.

By using the near-infrared(spectral range of 900-1700 nm) hyperspectral imaging technique, the soil moisture movement mechanism and non-destructive determination of the moisture content of soil in Ningxia Hui Autonomous Region were studied. A total of 208 soil samples were collected by hyperspectral imaging system. The differences among soil water content, spectral changes, and spectra of different water contents were compared. The best model was chosen by different spectral pretreatment manners, different extraction manners of the characteristic wavelengths(UVE, CARS, β coefficient, SPA), and different building model manners(MLR, PCR, PLSR). The results show that the changes of spectra are inversely proportional to the changes of soil water content within the moisture limits. When the moisture content of soil is beyond the field water holding capacity, the changes of spectra are directly proportional to the changes of soil water content. The unit vector normalized preprocessing method is optimized. The best model is MLR method based on the characteristic wavelength of SPA extraction. The optimal characteristic wavelengths are 987, 1386, 1466, 1568, 1636, 1645 nm, and the value of optimal correlation coefficient and RMSE are 0.984 and 0.631, respectively. Therefore, the soil moisture content can be quantitatively analyzed using different wavelengths.

Taking Ebinur Lake's major inflow tributaries (Bortala River and Jinghe River) as the research object, the fluorescence peaks of the water body were found by using the method of peak-searching. Using the color coordinate analysis method, the fluorescence emission spectral characteristics and fluorescence peak luminosity of Bortala River and Jinghe River were analyzed. Firstly, the fluorescence spectra of Bortala River and Jinghe River both have three fluorescence peaks, but the position of fluorescence peak and the peak intensity are different. The second fluorescence peak of Bortala River is much larger than the first fluorescence peak or almost as same as the first fluorescence peak. The intensity of the three fluorescence peaks in the first five samples of Jinghe River decreases with the increasing of the wavelength, and the first and the second fluorescence peak of sample 6 are almost the same. Secondly, the distribution of the three fluorescence peaks of Bortala River and Jinghe River are almost the same in the color coordinates, and the distribution of each fluorescence peak is concentrated in blue region, belonging to blue light emission. Finally, each fluorescence peak is clustered in the CIE coordinates. The first fluorescence peak is at the bottom of the color coordinates, The second fluorescence peak is distributed in front of the first fluorescence peak, and the x coordinate is close to the first fluorescence peak. The third fluorescence peak is aggregated in the upper right corner of the blue area.

In order to satisfy the high precision calibration of the detection capability of the star sensor under various spectral distribution, a design method of star simulator light source system based on digital micro-mirror device was proposed, and the issue of star sensor optical signal calibration precision caused by the mismatching between star simulator's color temperature and star sensor's detecting color temperature was partly solved. The principle of how color temperatures mismatching affected the calibration accuracy was analyzed, and a spectral tunable stellar spectrum simulation system based on digital micro-mirror device was designed. The genetic algorithm was used to perform spectral matching, and different spectral constructors were solved by the genetic algorithm to achieve the simulation of different spectra. Finally, the simulation system was simulated by three kinds of color temperature of 3900, 4800 and 6500 K at the spectral resolution of 5 nm and 20 nm. The simulation results show that the accuracy of the star spectrum is better than 2% at the spectral resolution of 5 nm and better than 5% at the spectral resolution of 20 nm.

For selecting optimal fluorescence excitation and emission wavelength of peak value method of concentration measurement, a multiple peaks linear regression parameters comparison method based on 3D fluorescence spectra was proposed. Taking 93# and 97# motor gasoline in the market for examples, firstly, 3D fluorescence spectra of purified water and motor gasoline from FS920 steady-state fluorescence spectrometers were analyzed and the characteristic fluorescence peaks were found. Secondly, 7 kinds of mixed liquors of 93# and 97# gasoline and water were prepared by volume ratio, respectively. Peak position and intensity etc. parameters of different sample were extracted. Results show that the characteristic fluorescence peak parameters are different for the different concentration. And then, for the mixed liquors of 93# and 97# gasoline and water, 23 peaks and 22 peaks were found by the exclusive method, respectively. Finally, the peak intensity and concentration data of each sample were fit by using the least square method. The comparison of adj. R-Square, F value, sensitivity and intercept, etc. shows that the optimal excitation/emission wavelength of 93# and 97# gasoline sample is 275/302 nm and 285/322 nm, respectively. Experimental results show that the absolute error of 93# and 97# concentration is 0.006‰ and 0.007‰, respectively. The precision of the calibration model founded by the optimal peak is one order higher than the traditional calibration model founded by the strongest peak.

Highly reflective one dimensional photonic crystal (1D PC) based on silicon thin films was investigated and prepared using the radio frequency plasma enhanced chemical vapor deposition method. Both the low refractive index layer of SiO_x and high refractive index layer of a-Si were deposited in the same chamber by alternatively changing the reaction gas component. The 1D PC has the advantage of high refractive index contrast, wide band gap, short depostion time and wide process window, which is a good candidate for the replacement of traditional high-reflection metal films. An average reflectivity of 99.1% was obtained within the bandgap (wavelength range of 650-1100 nm) for an 1D PC constructed with only 5 periods of SiO_x and a-Si, which is significantly higher than the Ag film of 96.3%.