摘要:Photonic crystal(PC) is a kind of material with periodic self-assembly structure at mesoscopic scale. The most significant characteristic of photonic crystal is the photonic band gap(PBG). The light whose wavelength is in the photonic band gap cannot be reflected back through the photonic crystal, so the photonic crystal has excellent light regulation ability. The modulation of luminescence intensity and lifetime of quantum dot materials is one of the research hotspots in this field. In this paper, silicon dioxide (SiO2) colloidal spheres were used as photonic crystal assembly units to prepare photonic crystal thin films with controllable thickness by electrophoretic deposition. Perovskite quantum dots(CsPbX3, X=Cl, Br, I) were prepared by thermal injection. After surface hydrophobicity modification, perovskite quantum dots are embedded in the periodic structure of photonic crystal, which has the effect of dual-mode display. In this work, the fluorescence enhancement of perovskite quantum dots by photonic crystal structure is realized, which has potential application value in display, anti-counterfeiting, photodetectors, light-emitting diodes and other fields.
摘要:Lead halide based perovskites have received a lot of attention from researchers in photovoltaic and optoelectronic fields in recent years due to their excellent photovoltaic properties and solution processable characteristics. However, the toxicity and instability of lead(Pb)-based perovskite have prevented them from being used in commercial applications on a large scale. The development of lead-free perovskite light-absorbing materials can effectively reduce their environmental toxicity and is a major trend in the future development of next-generation photovoltaic technologies. Here, we review the latest research progress of lead-free perovskite photovoltaic materials and systematically discuss their crystal structures, physicochemical properties, photovoltaic characteristics and their scenario applications. We focus on reviewing the research progress of three-dimensional non-lead chalcogenide compounds with structures similar to lead halide octahedra, and also discuss the research progress of two-dimensional Ruddlesden-Popper phase, low-dimensional defective phase lead-free perovskite compounds and non-perovskite compounds. Hoping this paper can provide an important reference for obtaining safe, stable and environmentally friendly next-generation optoelectronic materials.
摘要:Carbon dots(CDs), as a novel carbon nanofluorescent material, has attracted much attention due to its advantages of easy preparation, stable optical properties, low toxicity and good biocompatibility. However, the regulation of fluorescence properties, the improvement of fluorescence quantum yield(QY) and the search for green and sustainable carbon source are the key to realize its multifaceted application. Biomass materials have attracted extensive attention of scientists due to being widely existed in nature, rich in variety and capable of repeated regeneration. In the process of CDs preparation, the formation of carbon nuclei and surface states can be controlled simultaneously, which result in regulating the fluorescence performance and improving QY. In this paper, the researches on the green synthesis of biomass derived CDs(B-CDs) based on the regulation of the emitting light colors in recent years are summarized. And the effect on the fluorescence color and QY is analyzed according to the selection of biomass carbon source and synthesis method. Furthermore, the applications of B-CDs in biological imaging, drug delivery, sensing, anti-counterfeiting, photocatalysis and LED are discussed. At the same time, the challenges and future development direction of B-CDs in the aspects of performance optimization and green synthesis method are also prospected.
摘要:In order to develop a high gain medium for fiber lasers operating at 3-5 μm waveband, 0-0.4%(in weight) Pr3+ ions doped Ge12As20.8Ga4Se63.2 selenide chalcogenide glasses were prepared and the 0.2%(in weight) Pr3+ ions doped one was successfully drawn into step-index double-cladding fiber with the lowest loss of 2.95 dB/m@6.58 μm by a multistage rod-in-tube method. The electron-probe measure microanalysis(EPMA), X-ray diffraction(XRD), differential scanning calorimeter(DSC), field emission transmission electron microscope(FE-TEM), transmission and mid-infrared fluorescence spectra were carried out to analyze the dispersion of Pr3+ ions in glass, the impurity contents,thermal and optical changes caused by the Pr3+ ions’ introduction. By analyzing the absorption and emission measurements of the serial glasses with the Judd-Ofelt theory, the Judd-Ofelt strength parameters, transition probabilities, exited state lifetime, branching ratios, and emission cross-sections were also calculated. This selenide chalcogenide glass has high Pr3+ ions’ solubility and emission characteristic, good thermal stability and fiber forming performance, indicating that it has potential to be used as mid-infrared laser working medium.
摘要:The In0.49Ga0.51P material, as a semiconductor material with broad energy bandgap and matching lattice parameters with GaAs, has obtained widespread attention and application, such as GaAs-based short-wavelength lasers and aluminum-free lasers. Aiming on its applications in different fields, different demands are proposed on the properties of In0.49Ga0.51P materials, which lead to changes in the orderliness of In0.49Ga0.51P, and then, its luminescence properties. In this paper, the luminescence-characteristics effect of the orderliness of In0.49Ga0.51P material on semi-insulated GaAs substrate was studied using metal organic chemical vapour deposition(MOCVD) technology. The doping flux of SiH4 and DEZn and the change of Ⅴ/Ⅲ ratio can affect the ordering of In0.49Ga0.51P material. The results of room temperature PL test and low temperature PL test show that the increase of the doping flux of the two dopants can lead to the decrease of the order degree of In0.49Ga0.51P, thus causing the blue-shift of the emission wavelength of InGaP. In addition, the increase of Ⅴ/Ⅲ ratio leads to the increase of the orderess of In0.49Ga0.51P, which leads to the red shift of the luminescence wavelength of the sample.
关键词:metal organic chemical vapour deposition(MOCVD);InGaP/GaAs;photoluminescence;Intentional doping
摘要:Aggregation-caused quenching(ACQ) and aggregation-induced emission(AIE) molecules are highly emissive only in single molecular and aggregated state, respectively. This single-state emissive character highly hampers their applications. In this work, we synthesized a three-state(solution, gel and liquid crystal) highly emissive phasmid mesogen(PHAgen-12) and studied its self-assembly and photophysical properties. PHAgen-12 consists of a long rod-like part ended by two Percec-type dendrons. The rod-like core is “cyanostilbene + diphenyl-diacetylene+cyanostilbene”, featuring a D-A-π-A-D type emitter. PHAgen-12 can well dissolve in common solvents such as THF and DCM, form cylindrical micelle and further gel in selective solvents(alkanes), and develop into a hexagonal columnar liquid crystalline phase in bulk state, with four molecules in each monomolecule-thick(~0.44 nm) hexagonal unit cell. In dilute solution, it behaves like a ACQ molecule with a quantum yield(QY) up to 90.3 % in CHCl3. It renders a strong AIE character in condensed states, with a QY of 58.5% in PHAgen-12/dodecane gel system(30%(wt)) and a QY of 85.5% in bulk liquid crystalline state
摘要:A series of Sr3-xGa2Ge4O14∶xSm3+(x=0-0.20)and Sr2.88Ga2Ge4O14∶0.06Sm3+,0.06M(M= Li+, Na+, K+)phosphors were prepared via the high temperature solid-state reaction. The phase structure, crystal morphology, fluorescent spectra, temperature-dependent spectra, and CIE chromaticity coordinates of the samples were investigated. The optimal doping concentration in Sr3-xGa2Ge4O14∶xSm3+ was x=0.06, and the concentration quenching could be ascribed to the dipole-dipole interaction between Sm3+ ions. The luminescent emission intensities of Sr3-xGa2Ge4O14∶xSm3+ were greatly enhanced by co-doped M(M=Li+, Na+, K+)ions as charge compensator. The fluorescent decay lifetime became shorter when increasing Sm3+ concentration. The CIE chromaticity coordinates and thermal stability properties of Sr3-xGa2Ge4O14∶xSm3+ were discussed. The CIE chromaticity coordinates of Sr3-xGa2Ge4O14∶xSm3+ were located within the orange-red spectral region and the luminescent emission intensities could remain 95% of that at room temperature. All these results indicated that Sr3-xGa2Ge4O14∶xSm3+ could be a potential candidate as a novel orange-red emitting component applied in white light emitting diode(WLED).
摘要:A hybrid system of polyvinylcarbazole(PVK) and green indium phosphide(InP) quantum dots was designed to produce efficient light-emitting diodes(LEDs). PVK functions as not only disperse quantum dots well and reduce agglomeration, but also significantly reduce non-radiative Förster energy transfer(FRET) among quantum dots, and improve the film’s photoluminescence efficiency(PLQY) from 24.2% to 30.1%. Meanwhile, the incorporation of PVK can improve the hole transport performance of the QD film via the carrier balance of the devices, making the maximum external quantum efficiency(EQE) of the devices reach 5.94%, which is 32% higher than that of the devices without PVK. This method can provide a reference for the development of high performance green InP QD-LEDs.
摘要:(Cs0.8Rb0.2)(Pb0.93Zn0.07)(Br1.8Cl1.2) blue light perovskite quantum dots were obtained by co-doping Rb+ and Zn2+. Compared with undoped CsPb(Br1.8Cl1.2) quantum dots, Rb+, Zn2+ and halogen ions (Br-, Cl-) form a more stable perovskite octahedral crystal, which inhibits the formation of Cl- vacancy defects, which improves the stability of quantum dots. The photoluminescence efficiency of the doped quantum dot solution was significantly improved from the undoped 5% to 52%, and the radiative recombination was also significantly enhanced. The co-doping of Rb+ and Zn2+ shifts the HOMO level of the quantum dots up by 0.31 eV, which reduces the injection barrier from the hole transport layer (HTL) to the emissive layer (EML), which is beneficial to hole injection. Based on blue perovskite quantum dots co-doped with Rb+ and Zn2+, a light-emitting device with the structure of ITO/PEDOT∶PSS/TFB/Pe-QDs/TPBi/LiF/Al was designed. For blue light emission at 19 nm, the maximum external quantum efficiency(EQEmax) reaches 3.55%.
摘要:Herein, We fabricated a CuSCN nanofilm ultraviolet(UV) photodetector(PD) using an in situ growth method. When the bias is -1 V and the incident light is 350 nm, the on/off ratio of the CuSCN PD is ~94, and the rise/decay time is ~1.41 s/1.44 s. However, such a device still cannot be called a high-performance photodetector. To improve the optoelectronic properties of CuSCN nanofilm further, we fabricated a UV photodetector based on n-ZnS/p-CuSCN composite nanofilm and analyzed its morphology, composition, and properties. The photocurrent and dark current of the ZnS/CuSCN UV photodetectors are 1.22×10-5 A and 4.8×10-9 A, respectively(at -1 V, 350 nm). The ZnS/CuSCN nanofilms' on/off ratio of ~2 542 and rise/decay time is 0.47 s/0.48 s. Besides, the n-ZnS/p-CuSCN nanofilm UV PDs have the best responsivity and detectivity at 350 nm with 5.17 mA/W and 1.32 × 1011 Jones, respectively. In addition, the n-ZnS/p-CuSCN composite film is stable at room temperature, which indicates its great potential as a high-performance UV photodetector.
关键词:photodetector;p-n junction;ZnS/CuSCN;on/off ratio
摘要:As a popular hole transport material, poly(3,4-ethylenedioxythiophene)∶poly(styrene sulfonate)(PEDOT∶PSS) has been widely used in variety of optoelectronic devices. High boiling-point solvents were usually added into PEDOT∶PSS solutions to enhance its conductivity, but simultaneously resulted in evident leakage current due to solvent residue. However, low boiling-point solvents, which are more easily removed, have not been effectively utilized. In this study, we found that the performance of the corresponding poly(3-hexy-thiophene)(P3HT)∶[6,6]-phenyl-C61-butyric acid methyl ester(PC61BM) polymer solar cells(PSCs) was improved without increasing the leakage current after low boiling-point solvent treatment of PEDOT∶PSS films by dripping isopropanol, ethanol or acetone then spin-coating. Especially, after the isopropanol treatment, the short-circuit current density of PSC increased from 8.15 mA/cm2 to 9.17 mA/cm2, and the power conversion efficiency reached 3.5%, an 18.6% enhancement compared to the control device. The analysis revealed that the solvent-treated PEDOT∶PSS films demonstrated diffetent surface morphology, enhanced light transmission, and improved electrical conductivity due to the phase separation between PEDOT and PSS chains. Meanwhile, the hole transport capability of PEDOT∶PSS increased after treatment, especially after the isopropanol treatment. These results suggested that low boiling-point solvents could be effectively utilized by this method and improved the optoelectronic properties of the PEDOT∶PSS film.
关键词:poly(3,4-ethylenedioxythiophene)∶poly(styrene sulfonate)(PEDOT∶PSS);low boiling-point solvents;solvent treatment;polymer solar cells
摘要:Organic light emitting diode on silicon is an important research topic in the microdisplay field. In the paper, we present a systematic study about the influence of plasma treatment to the titanium nitride, which is the key interface between the anode and organic layers. The changes of characteristic parameters, including the morphology of surface microstructure, work function, carrier concentration, carrier mobility, reflectance, and the X-ray photoelectron spectroscopy after plasma treatments, are summarized to optimize the performance of integrated organic light emitting diodes. The results show that the plasma treatment with appropriate power(60 W for O2 or 80 W for N2) can significantly improve the luminance(70% for O2 and 128% for N2) of display device on silicon. Meanwhile, the current and power efficiency are increased by 35% and 58%, respectively. It was revealed that the valence states of Ti and N are changed during the plasma treatment, which are considered to improve the interfacial carrier concentration and mobility for an enhanced luminescence performance. This study elaborates an approach to improve the performance of a typical microdisplay device on silicon and provides a guide for related researches.
关键词:plasma treatment;organic light emitting diode(OLED)-on silicon;titanium nitride;carrier concentration and mobility
摘要:Molecularly imprinted polymer probes(Eu-MIPs) modified by lanthanide complexes were prepared by chemical bonding of molecularly imprinted polymers(MIPs) and lanthanide Eu3+ complex-functionalized ionic liquid([Eu(BFA)3]@DPA-PA) by sol-gel method. The structure and properties of the probe molecules were analyzed by characterization methods such as FT-IR, XPS, UV-Vis, and PL. The results show that the Eu-MIPs fluorescent polymer has excellent fluorescence properties. In addition, by further studying the fluorescence sensing performance of Eu-MIPs for hemoglobin(Hb), it was found that Hb can produce a significant quenching effect on the fluorescence of Eu-MIPs, which may be due to the competitive absorption of UV light by Hb and ionic liquid ligands, and then the energy transfer process between ligands and rare earths is affected, resulting in the fluorescence quenching of Eu-MIPs. At the same time, Eu-MIPs have strong selectivity and anti-interference ability to Hb, and are expected to be used as fluorescent probes for the specific detection of Hb.
摘要:As a new class of metal-free fluorescent nanomaterials, sulfur quantum dots(SQDs) have attracted increasing attention because of their unique composition, excellent optical properties and low toxicity. However, the SQDs usually suffer from the drawbacks of low fluorescence quantum yield(QY) and long preparation time, which significantly limit the practical application of SQDs. In this paper, we report a simple and viable method to prepare SQDs with high QY based on the one-step solvothermal treatment of elemental sulfur-ethylenediamine(EDA) precursor at 175 ℃ for 4 h. The prepared SQDs exhibited excellent water solubility and nearly monodisperse size distribution with size in the range of 1.6-3.8 nm. Different from other reported SQDs, the obtained SQDs showed excitation-independent emission behavior. The emission peak of the SQDs did not change with the variation of excitation wavelength. The maximum emission intensity was achieved when the excitation wavelength was 340 nm. Moreover, the fluorescence QY of SQDs was determined to be as high as 87%, which is much higher than other reported SQDs. The SQDs also displayed good fluorescence stability. When the solution pH was changed in the range of 4-9 or the SQDs solution was stored at room temperature for one month, the fluorescence intensity of SQDs did not change significantly. Furthermore, the SQDs can be used as an effective fluorescent probe for highly sensitive and selective detection of 4-nitrophenol(4-NP). Owing to the presence of inner filter effect, the 4-NP can effectively quench the fluorescence of SQDs. When the concentration of 4-NP was in the range of 2-85 μmol/L, there was a good linear relationship between the relative fluorescence intensity(I/I0) of SQDs and the concentration of 4-NP. The limit of detection was calculated to be as low as 73.4 nmol/L. In addition, the SQDs were also successfully employed to sense 4-NP in tap water and river water with satisfactory performance.
摘要:There are various types of biometal ions and biomolecules in the organism and their content changes can reflect the health of living body. Therefore, it is very important to develop a detection method for monitoring the content of biometal ions or biomolecules in biological systems. In recent years, fluorescent materials with enhanced properties of aggregation-induced emission(AIE) have shown wide application prospects in the fields of optoelectronic materials, chemical sensing, and bio-imaging due to their unique optoelectronic properties and biological activities. At present, tetraphenylethylene(TPE) has become one of the most representative and commonly used molecules among aggregation-induced luminescent molecules(AIEgens) with high fluorescence quantum yield, which has the advantages of simple synthesis, easy to functionalize, and excellent AIE effect. This paper reviews the research progress of tetraphenylethylene-based fluorescent materials in the detection of biometal ions, small biomolecules and biomacromolecules in recent years. The challenges faced of fluorescent probes are analyzed and the development prospects are expected. It is expected to provide a reference for preparing and synthesizing fluorescent probes with good biocompatibility and low detection limit.
摘要:Thiophenol(PhSH) is a highly toxic substance, which does great harm to environment and health. Therefore, the rapid detection of PHSH in the environment is of great significance. In this work, the carbon dot(CD)-based nanoprobe CD-DNS used 2,4-dinitrobenzenesulfonyl as the recognition group was performed to achieve a highly selective detection of PhSH in the environmental samples. The CD-based nanoprobe CD-DNS solution exhibited very weak fluorescence and absorbance. After adding PhSH, the 2,4-dinitrobenesulfonamide moiety of CD-DNS could be readily cleaved via nucleophilic substitution reaction, leading to a dramatic increase of fluorescence intensity and absorbance of the probe. Further studies showed that the fluorescence intensity at 520 nm and absorbance at 440 nm of the probe showed a good linear relationship with the PhSH concentration, with a linear range of 0-5 μmol/L. The established detection probe displayed fast reaction(4 min) and high selectivity towards PhSH. In addition, CD-DNS could be used for the detection of PhSH in environmental water samples, and also could be prepared into a strip to realize the semi-quantitative visual detection of PhSH. The experimental results show that the CD-based nanoprobe CD-DNS has a potential application prospect in the environmental field.