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Eu³⁺ doped alkaline earth bismuth borate glasses(BBME, BBCE, BBSE, BBBE)were prepared by the rapid melt quenching technique. The general physical properties including density, molar volume, optical basicity and so on were studied, the structure, optical properties as well as thermal stability of the glasses were investigated. The tightness of the glass decreases from BBME to BBBE. Eu³⁺ melts homogeneously in the glasses and acts as a well activator. The intense emission peaked at 613 nm is observed in the emission spectra under 465 nm excitation. the intensity increases gradually from BBME to BBBE. All the glass samples present amorphous states and have low symmetric structure, and the symmetries decrease from BBME to BBBE. The asymmetric[BO₃] units, loose[BO₄] units,[BiO₃] units and tri-, tetra-, penta-borate groups including[BO₃] units are identified in the glass samples, however, six member rings and penta-borate, pyro-borate, ortho-borate groups consisting of[BO₃] are not observed. The glass samples with well thermal stability, low melting temperature and appropriate refractive index are expected to be good candidates applied for WLED glass ceramic in the future.

The mismatch between band gap of silicon cell and solar spectra results in serious loss of energy, which greatly reduces the efficiency of silicon solar cell. In order to decrease the loss of incident photons like ultraviolet (UV) photons, the photoluminescence materials with near-infrared (NIR) quantum cutting (QC) effect can be used as spectra transformation materials to enhance the efficiency of silicon solar cells. As a novel kind of efficient NIR quantum cutting material, Sr₃Al₂O₆:Tb³⁺,Yb³⁺ phosphors promising for silicon solar cells were successfully prepared using sol-gel method. The luminescence properties of Sr₃Al₂O₆:Tb³⁺,Yb³⁺ were investigated using photoluminescence (PL) spectra and decay lifetime curves. The results show that the phosphors can emit visible light of Tb³⁺:⁵D₄→⁷F_j under the excitation of 320 nm, while NIR light is emitted by Yb³⁺:⁷F_5/2→⁷F_7/2 through cooperative energy transfer from one Tb³⁺ ion to two Yb³⁺ ions. Decay lifetimes of Tb³⁺ and quantum efficiency (QE) were studied for Sr₃Al₂O₆:Tb³⁺ and Sr₃Al₂O₆:Tb³⁺,Yb³⁺. The results show that there is effective cooperative energy transfer from Tb³⁺ to Yb³⁺, in which maximum energy transfer efficiency (ETE) and the corresponding quantum efficiency are estimated to be 35.9% and 135.9%, respectively. The results demonstrate that Sr₃Al₂O₆:Tb³⁺,Yb³⁺ phosphors are promising candidate for improving the efficiency of silicon based solar cell by means of down-conversion.

Yb³⁺ and Tm³⁺ co-doped silicate glasses with different contents of Li⁺ were prepared by high temperature melting, which could emit 477 nm blue and 654 nm red light under 980 nm LD pumping. The double logarithmic linear fitting of light emission intensity and pump power show that the probability of Tm³⁺ upward transition in up-conversion process increases after the adding of Li⁺ because of the number of electrons populated at ³F₂ and ¹G₄ energy levels of Tm³⁺ increasing, which leads to improving the probability of radiation transition. The infrared spectra and Raman spectra show that the addition of Li⁺ has little effect on phonon energy of the glass substrate, however, the density of phonon states decreases. Finally, the luminescence intensity of Yb³⁺ and Tm³⁺ in silicate glass is improved by increasing the up-conversion efficiency.

Nd³⁺/Yb³⁺ doped YNbO₄ powder sample was prepared with the molar ratios of 50Nb₂O₅-40Y₂O₃-2Nd₂O₃-8Yb₂O₃ by the high temperature solid state method at 1 300℃. The spectrum property was studied by using Judd-Ofelt theory. The spectral strength parameters Ω_λ (λ=2, 4, 6) were computed based on the absorption peak's area of the absorption spectrum. The theoretical oscillator strength and the experimental oscillator strength were calculated according to the spectrum strength parameters, and the root mean square deviation (δ_rms) of them was 1.618×10^-7. The parameters such as transition probability, decay branching ratios and level lifetime of Nd³⁺ transition ⁴F_3/2→⁴I_J'(J'=15/2, 13/2, 11/2, 9/2) were obtained. The decay branching ratio of ⁴F_3/2→⁴I_11/2 (corresponding to the wavelength of 1 062 nm) is the most of 56.91%. The lifetime of metastable level ⁴F_3/2 is longer of 1.435 2 ms, which is suitable for up-conversion intermediate level. Under the excitation of 980 nm diode laser, the up-conversion luminescence is observed at the wavelength of 487, 541 and 662 nm, corresponding to the radiative transitions of Nd³⁺:²G_9/2→⁴I_9/2, ⁴G_7/2→⁴I_9/2 and ⁴G_7/2→⁴I_13/2, respectively. The two-photon absorption of three emission peaks is determined by the fitting curve graph of sample up-conversion emission power and the laser working current when the absorption of the photon number in turn is 2.06, 1.99 and 2.15.

Al and/or Sm doped ZnO block films were prepared by sol-gel method, and characterized by XRD, EDS, FTIR, PL, UV-Vis and SEM to investigate the effects of Al and Sm doping content on the performance. When the doping mole fraction of Al is 1%, and that of Sm is 3%, the photoluminescence intensity of the block film is the highest. The film can down-convert part of ultraviolet light to visible light of 588 nm, which widens the spectra response range. By using ZnO:Al,Sm down-conversion film and TiO₂ (P25) porous absorbing layer, after sensitized by the pigment ethanol solution of spines of sea urchin, the short-circuit current density and open-circuit voltage of the dye sensitized solar cell (DSSC) are 0.68 mA/cm² and 0.73 V, respectively. And the DSSC achieves the power conversion efficiency of 0.33%, which is increased by 136% compared to the DSSC based on ZnO block layer.

The phosphors of Sr₇Zr(PO₄)₆:Tb³⁺, Sr₇Zr(PO₄)₆:Ce³⁺ and Sr₇Zr(PO₄)₆:Tb³⁺,Ce³⁺ were prepared by the solid-state reaction. The structures of these powders were characterized by X ray diffractometer (XRD). The excitation and emission spectra were characterized by spectrofluorimeter. The excitation spectrum of Sr₇Zr(PO₄)₆:Tb³⁺ shows a narrower band in the range of 200-250 nm with the maximum centered at 226 nm, which belongs to ⁷F_J→⁷D_J transition of Tb³⁺. The photoluminescence spectra of Sr₇Zr(PO₄)₆:Tb³⁺ exhibits four emission peaks. The strongest green emission peak is at 543 nm which belongs to ⁵D₄→⁷F₅ transition of Tb³⁺. The excitation spectrum of Sr₇Zr(PO₄)₆:Ce³⁺ shows a broad band centered at 289 nm and the emission peak is at 374 nm. In order to broaden the width of the excitation band of Sr₇Zr(PO₄)₆:Tb³⁺,Ce³⁺ ions are incorporated. It is found that the excitation band became broader. The excitation spectrum of Sr₇Zr(PO₄)₆:Ce³⁺,Tb³⁺ shows two broad bands, respectively, the former belongs to the excitation of Tb³⁺ and the latter belongs to the excitation of Ce³⁺. The emission spectra of Sr₇Zr(PO₄)₆:Ce³⁺,Tb³⁺ exhibit strong emission peaks of Tb³⁺ excited by 289 nm, which is the excitation band center of Ce³⁺. It is speculated that the energy transfer occurs from Ce³⁺ to Tb³⁺.

Polyethylene glycol (PEG) was doped into the PEDOT:PSS layer of CH₃NH₃PbI_xCl_3-x perovskite solar cells to improve the power conversion efficiency (PCE) and reduce the hysteresis of the device. The capacitance-voltage (C-V) and the current density-time (J-T) transient measurements were used to study the charge accumulation and defects between the buffer layer and the active layer. The results show that the short circuit current (J_sc), the open circuit voltage (V_oc), the fill factor (FF), and the power conversion efficiency (PCE) of the device with PEG are improved. The PCE of the device with PEG reaches 10.0% which is 33% higher than that of the control device and the hysteresis of J-V curve is also reduced with the introduction of PEG. PEG can improve the device properties by reducing the charge accumulation and decreasing the defects which is beneficial to electron collection and reducing hysteresis.

In order to realize the preparation of large-area periodic micro-nano structures to enhance the luminous efficiency of LEDs, Lloyd laser interference lithography (LIL) system was established. The working principle of LIL system was simply analyzed and the experimental process of preparing the one-dimensional gratings, two-dimensional lattice and hole arrays was introduced. Finally, the nano-structures were transferred into suitable functional substrates for further applications. The experimental results indicate that the uniform gratings or two-dimensional lattice arrays structures with the period of 450 nm, whose duty cycle can also be changed, are successfully fabricated on 20 mm×20 mm ITO substrates by using the LIL system.

As a wide band gap semiconductor device, GaN based Schottky barrier diode (SBD) has the characteristics of high voltage, high thermostability, low conduction resistance and other excellent characteristics, which makes it widely used in the field of power electronics. This paper first summarizes the problems to be solved in the development of SBD. Then, the structure, working principle and structure optimization of GaN SBD are introduced. Next, the structure, working principle and structure optimization of AlGaN/GaN SBD are summarized, and the effects of these structures on the performance of AlGaN/GaN SBDs are discussed from the perspective of epitaxial wafer structure, Schottky electrode structure and edge termination structure of AlGaN/GaN SBD.

Highly efficient blue organic light-emitting diodes based on mixed host structure were successfully fabricated. Two blue devices with structure of single host and double emission layers were fabricated as comparison. It is showed that the employment of mixed host structure can enhance the performance of blue device obviously. The mixed host blue OLED with low turn on voltage of only 2.7 V shows maximum efficiencies of 14.9 cd/A (13.3 lm/W) and maximum luminance of 10 440 cd/m². Moreover, this blue device also shows very low efficiency roll-off. The current efficiency only drops 35.3% from the luminance of 100 cd/m² to 5 000 cd/m².

The electrical and optical properties of blue organic light-emitting diodes fabricated by utilizing nickel-oxide nano buffer layers between the anodes and hole transport layers were investigated. NiO nanolayer on ITO was prepared by the electrochemical methods. The effects of NiO nanolayer on the device performances were studied. The experimental results show that NiO buffer layer can effectively enhance the probability of hole-electron recombination due to an efficient holes injection into and charge balance in an emitting layer. The sample with Ni deposition time of 30 s has the highest luminance of 42 460 cd/m², maximum current efficiency of 24 cd/A, and CIEx,y coordinates of (0.212 9, 0.325 2), respectively.

The amplified spontaneous emission (ASE) properties of phenyl, naphthyl and anthracene substituted boron dipyrromethene (BODIPY) derivative films were studied, and the factors that influence the ASE stability of BODIPY derivatives were discussed. First, three BODIPY derivatives (PhBOD, NaBOD and EnBOD) materials were doped into polystyrene, from which the films were prepared by spin-coating. The absorption and fluorescence spectra were recorded. The ASE performance of the three samples was measured under the optical pumping, and the ASE thresholds of the materials were obtained. The optical stability, ASE environmental stability and thermal stability of the materials were studied by means of long time pumping, long time placement in the environment and pumping under high temperature environment. Finally, Gaussian 09 was used to calculate the molecular ground state properties. Experimental results show that the initial thresholds of PhBOD, NaBOD and EnBOD films are about 12.4, 4.55, 3.4 kW/cm², respectively. Among them, PhBOD film shows better ASE stability. The difference of ASE stability may be related to the conjugation degree and chemical stability of molecular structure. The ASE stability of the material would be better when the conjugation degree of each group in the molecule is larger, and the Mulliken charge distribution is more symmetrical.

In order to reduce the turn on voltage and improve the performance of QLED, ZnO film with good electronic transmission property was used as electron transport layer. The structure of the sample was ITO/PEDOT:PSS/Poly-TPD/QDs/ZnO. The models of Folwer-Nordheim tunneling injection and space-charge limited current were employed to analyze the injection current density in QDs layer. The results show that the optimal thickness of poly-TPD is confirmed to 40 nm when ZnO thickness is fixed of 50 nm, and the injection carriers in QDs layer can reach a certain balance. By measuring the current density-voltage-luminance-luminous efficiency of QLED, the influences of hole transport layer thickness on the device performance were studied. Experiment results show that the device with a hole transport layer of 40 nm has the best performances than the other devices, of which the turn on voltage is 1.7 V, the maximum lumious efficiency is 1.18 cd/A, and the maximum brightness can reach 5 225 cd/m² under the voltage of 9 V.

In order to adjust the exciton recombination zone of exciplex-based organic light-emitting diodes, four devices were fabricated by employing Ir(pq)₂(acac) as a prober and utilizing the donor of exciplex as a spacer. The device structures are ITO/MoO₃(2.5 nm)/TPD((40-x) nm)/Ir(pq)₂(acac)(0.5 nm)/TPD(x, x=0, 3, 6, 10 nm)/BPhen(40 nm)/Cs₂CO₃/Al, where x is the thickness of the spacer layer and the TPD/BPhen interface produces the exciplex emission. The electroluminescent spectra of the four devices include two main peaks:478 nm and 595 nm, which originate from the TPD/BPhen interface and Ir(pq)₂(acac) layer, respectively. As both the thickness of TPD spacer and the applied voltage increase, the recombination zone shifts towards TPD/BPhen interface. That is, more electrons and holes recombine at the interface between TPD and BPhen, leading to the decreased intensity of Ir(pq)₂(acac) emission. For instance, under an applied voltage of 6 V, the intensity ratio of emission from Ir(pq)₂(acac) and exciplex (I_{Ir complex}:I_exciplex) is 44.0 and 1.5 for the devices with 0 and 10 nm spacer, respectively. The value of I_{Ir complex}:I_exciplex decreases from 2.8 at 6 V to 1.0 at 10 V for the device with 6-nm-thick TPD spacer. Therefore, the recombination region can be effectively tuned by utilizing the donor of exciplex as a spacer.

Based on the small-angle approximation condition, the radiation propagation equation of the laser signal in dust weather was deduced by using sequential recursive method, the distribution of light intensity under multiple scattering was obtained, and the wavelength and the asymmetry factor's influence on the scattering light intensity were also analyzed. Furthermore, by comparing the different scattering phase functions and the scattering characteristics of the dust particles, an amended Two Term Henyey-Greenstein (TTHG) phase function was adopted, which can reflect the scattered light intensity distribution more comprehensive. The results show that the scattered light intensity increases firstly and then decreases with the increasing of the optical thickness, and the proportion of the multiple-scattering becomes larger gradually. When the scattering number is more than three times, the change of the received light intensity can be ignored. Compared with Mie theory, the results of the small-angle approximation method are more reliable, which can accurately describe the laser signal transmission characteristics in dust weather.

Water-soluble carbon quantum dots (CQDs) were prepared by using citric acid as carbon source. The obtained CQDs showed a strong emission at the wavelength of 484 nm, with an optimum excitation of 394 nm. Sunset yellow with maximum absorption wavelength at 482 nm could selectively quench the fluorescence of CQDs. Based on this principle, a fluorescent probe was developed for sunset yellow determination. Furthermore, the quenching mechanism of the CQDs was elucidated. A linear relationship was found in the range of 0.1-100 μmol/L sunset yellow with the detection limit (3σ/k) of 0.051 μmol/L. Satisfactory results were achieved when the method was submitted to the determination of sunset yellow in liquid samples.

The interaction between sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfonate (SDS) could have a significant impact on the quantitative analysis of SDBS in water. The results indicate that the existence of SDS not only can improve the synchronous fluorescence intensity of SDBS but also can greatly decrease the apparent critical micelle concentration values of SDBS. The interference of SDS on the synchronous fluorescence intensity of SDBS can be greatly reduced by adding 1:1 HP-β-CD according to the molar amount of SDBS. The results also show that SDBS molecules are more likely to form SDBS/HP-β-CD inclusion with the molar ratio of 1:1 rather than micelles in HP-β-CD aqueous solution. Thus, the standard molar Gibbs free energy for SDBS from aqueous SDS/SDBS binary blend solution to the micelle, ΔγG_m^θ, increases from -39.681 kJ·mol^-1 to -37.580 kJ·mol^-1 while the concentration of HP-β-CD increases from 0 to 0.900 mmol·L^-1. The concentration of SDBS in aqueous SDS/SDBS binary blend solution (water samples taken from T5 sites of LinPan oilfield), can be accurately determinated by adding proper amount of HP-CD, and the recovery rate of SDBS is 101.0%-101.6%. The results of ¹H-NMR and FT-IR exhibit that the interference of SDS on quantitative determination of SDBS can be greatly reduced because of the formation of SDBS/HP-β-CD inclusion (molar ratio of 1:1) with SDBS molecule locating within the broad mouth of HP-CD molecule.

The adsorption characteristics and regularity of cytosine (Cy) on the silver substrate surface were analyzed by the means of surface enhanced Raman scattering (SERS) combing with quantum chemistry density functional theory (DFT). The normal Raman spectrum (NRS) of Cy and Cy-Ag_n complex (n=1, 3, 5) SERS spectra were calculated by DFT/B3LYP method, which were further compared with the measured results to identify and assign the spectral peaks. The SERS spectra of Cy molecules on silver colloid nanoparticles were recorded at different adsorption time, concentration and pH. The results show that pH value has the greatest influence on its SERS signal, especially at neutral and strong alkaline conditions. It is inferred that there are two different isomers of Cy molecules and three kinds of existing forms, and all of them keep dynamic balance in the solution. The adsorption mechanism of Cy on the surface of silver substrate was further discussed in detail based on the morphological distribution of Cy at different pH by their corresponding SERS changes combining with the DFT calculation of charge distribution in Cy molecules. In conclusion, the N³ and O in Cy are coordinated to Ag at the neutral and weakly alkaline conditions. N and Ag form coordinated adsorption and O and Ag form covalent adsorption, when the pH is greater than 11.

Based on the Lee-Low-Pines unitary transformation, the electromagnetic-field dependence of the eigenenergy, the eigenfunctions, and the mean number of phonons of both the ground-state and the first excited-state of the strong-coupling polaron in the quantum dot with the thickness were studied by using the Pekar variational method. On this basis, the quantum dot qubit was formed by means of the two-level structure of the polaron as the carrier. The results of numerical calculation indicate that the oscillation period T₀ of the qubit increases with the increasing of the thickness L of the quantum disk, but decreases with the increasing of the cyclotron frequency ω_c of the magnetic field, electric-field strength F and electron-phonon coupling strength α.The probability density |Ψ(ρ,z,t)|² of the qubit presents the normal distribution with the variation of the electronic transverse coordinate ρ. It is significantly influenced by the thickness L and effective radius R₀ of the quantum disk and shows the periodic oscillation with the variation of the electronic longitudinal coordinate z, polar angle φ and time t. The decoherence time τ increases with the increasing of the cyclotron frequency ω_c of the magnetic field, dispersion coefficient η and electron-phonon coupling strength α, but decreases with the increasing of the electric-field strength F, thickness L and effective radius R₀ of the quantum disk. The thickness of the quantum dot is an important parameter of the qubit. Theoretically, the target of regulating the oscillation period, decoherence time and quality factor of the free rotation of the qubit can be achieved by designing the different thickness of the quantum disk and regulating the strength of the electromagnetic field.