摘要:Formamidinium lead bromide perovskite nanocrystals(FAPbBr3 NCs) have attracted widespread attention due to their excellent performance in optoelectronic applications. Notably, the utilization of amines as ligands for effective surface passivation of perovskite nanocrystals has been proven to be an effective method for enhancing device performance. In this work, FAPbBr3 NCs with two different amine ligands (long-chain oleylamine and short-chain hexylamine) were prepared using ligand-assisted reprecipitation technology. Their excited-state carrier dynamics were studied by transient absorption (TA) spectroscopy and time-resolved photoluminescence (TRPL), revealing that NCs with oleylamine ligands exhibit longer carrier lifetime and slower carrier relaxation dynamics, indicating that long-chain oleylamine can effectively passivate surface defects and promote radiative recombination. The temperature dependence of FAPbBr3 NCs was investigated using steady-state photoluminescence spectroscopy. The results showed that as the temperature increases, exciton-phonon coupling is enhanced, leading to an increase in linewidth and photon energy of the emission peak. The exciton binding energy in long-chain oleylamine-ligated FAPbBr3 NCs was determined to be approximately 62.9 meV, and the longitudinal optical phonon energy was approximately 30.5 meV. The research results confirm the role of amine ligands in regulating the optical properties of FAPbBr3 NCs, providing important guidance for the design of high-performance optoelectronic devices.
摘要:All-inorganic lead halide perovskite quantum dots (QDs) can obtain excellent luminescence properties via room-temperature preparation. However, the naturally ultra-fast growth rate of perovskite nanocrystals make it difficult to achieve ultrasmall size and quantum size effect inducing deep blue light emission of perovskite QDs, especially at room temperature. Here, a suppressing growth rate method was developed to prepare the deep blue CsPbBr3 QDs at room temperature. Based on the ligand-assisted reprecipitation process, terpinene was introduced into the precursor preparation to slow down the supply of Cs ions in the growth of CsPbBr3 QDs after nucleation stage. As a result, the growth time of deep blue light CsPbBr3 QDs was extended to 3 hours. Furthermore, this method realized the effective control of the photoluminescence (PL) emission peak of CsPbBr3 QDs from deep blue light (447 nm) to green light (517 nm). In addition, combined with the regulation of terpinene proportion, the effect of reducing the growth rate of terpinene was further demonstrated. This work is of great significance for the growth regulation of perovskite nanocrystals.
关键词:perovskite quantum dots;deep blue light emitting;growth rate;CsPbBr3;room-temperature preparation
摘要:Metal halide perovskite materials have great potential for development in the fields of lighting, display, and other optoelectronics due to their simple preparation process and unique optoelectronic properties. Currently, perovskite light-emitting diodes(PeLEDs) have made some progress in the fields of green light and red light. However, there are still big challenges to realize high-efficiency blue PeLEDs. In recent years, researchers have realized the blue light modulation of perovskites mainly through two ways: component engineering and dimensional engineering. Among them, quasi-two-dimensional perovskite materials have self-assembled quantum well structures, which exhibit unique advantages in blue light emission. As a result, this paper summarizes the current progress related to quasi-two-dimensional perovskite blue light diodes. Firstly, the quasi-2D perovskite blue light material system is briefly introduced, and then the structure and optical properties of quasi-2D perovskite are described. Secondly, focusing on the light-emitting layer of the device, we systematically summarize the methods and strategies to improve the performance of the device and finally put forward a partial summary and outlook on the development of quasi-2D perovskite blue light diodes in anticipation of a continuous breakthrough in their performance.
摘要:A liquid crystal display, if lit by the white light-emitting diodes backlight that fabricated with a fluoride red phosphor showing a dominant photoluminescence emission wavelength longer than that of the commercially used fluoride phosphor, would exhibit a broadened color gamut. This review summarizes the Mn4+-activated fluoride phosphors that exhibit their dominating luminescence wavelength in the range of 632 nm to 637 nm. A comprehensive analysis was conducted to elucidate the correlation between the luminescence wavelengths and factors, including the valence and effective ionic radius of the cation being substituted, the octahedral distortion, the polarization force of adjacent cations, etc.
摘要:Halide perovskite materials have demonstrated significant potential in the field of photoelectric materials due to their excellent photoelectric properties. However, their inherent instability limits their practical application to some extent. In recent years, there has been increasing attention on the synthesis of new composites using metal-organic frameworks (MOFs) to encapsulate halide perovskites. By encapsulating halide perovskites within MOFs, stability can be significantly improved under conditions such as humidity, temperature, and light, leading to unique performance advantages. This paper provides a comprehensive review of the latest functions and applications of perovskite-metal organic framework composites (PeMOFs) in photoelectric conversion. The preparation strategy and research progress of PeMOF are described in detail, followed by an analysis of the unique role played by MOF in PeMOF. Finally, this paper summarizes the latest research progress on PeMOFs in the fields such as perovskite solar cells (PSCs), photocatalysis, sensors, light-emitting diodes (LEDs), fluorescent anti-counterfeiting and information encryption techniques, radiation protection, and detection, while also discussing future development directions and application prospects.
关键词:halide perovskite;metal-organic frameworks;stability;photoelectric material
“In the field of near-infrared nano-photoelectronic devices, GaAs-based nanomaterials are crucial due to their superior optoelectronic properties. Expert xx established the GaAs/AlGaAs core-shell heterostructure system, which provides solutions to solve the problems of type-Ⅱ quantum well structures and surface defects in GaAs nanowires.”
摘要:GaAs-based nanomaterials are essential for near-infrared nano-photoelectronic devices due to their exceptional optoelectronic properties. However, as the dimensions of GaAs materials decrease, the development of GaAs nanowires (NWs) is hindered by type-Ⅱ quantum well structures arising from the mixture of zinc blende (ZB) and wurtzite (WZ) phases and surface defects due to the large surface-to-volume ratio. Achieving GaAs-based NWs with high emission efficiency has become a key research focus. In this study, pre-etched silicon substrates were combined with GaAs/AlGaAs core-shell heterostructure to achieve GaAs-based NWs with good perpendicularity, excellent crystal structures, and high emission efficiency by leveraging the shadowing effect and surface passivation. The primary evidence for this includes the prominent free-exciton emission in the variable-temperature spectra and the low thermal activation energy indicated by the variable-power spectra. The findings of this study suggest that the growth method described herein can be employed to enhance the crystal structure and optical properties of other Ⅲ-Ⅴ low-dimensional materials, potentially paving the way for future NW devices.
摘要:Quasi two-dimensional (Q-2D) lead halide perovskites have attracted much attention due to the high stability of two-dimensional(2D) perovskites and the high light absorption efficiency of three-dimensional(3D) perovskites. However, the luminescent efficiency of Q-2D lead halide perovskite is usually low and has the issue of lead toxicity. Herein, Mn2+ doped Q-2D lead halide perovskites PEA2MAPb2Br7∶Mn (PEA: phenylethylamine; MA: methylamine) were prepared by using a facile antisolvent method at room-temperature. Mn2+ doped Q-2D perovskites show bright orange emission under 365 nm light excitation. The emission spectra show several weak excitonic emission peaks and a strong board band emission centered at 610 nm which is attributed to characteristic emission peaks of Mn2+.The photoluminescence quantum yield (PLQY) of Mn2+ doped Q-2D lead halide perovskites increases to 50.25% compared to the pristine sample with 1.49%. The reason is that Mn2+doping reduces the 3D phase ratio in Q-2D perovskite and increases the 2D phase ratio. Due to the significant quantum confinement effect of the 2D phase, the energy transfer efficiency between the host and dopant ions is effectively improved. This work explores the strategy of ion doping to regulate the phase structure of Q-2D and energy transfer from host to dopant, which improves the luminescence efficiency with tunable luminescence wavelength. It provides insights for the development of perovskite halides with tunable wavelengths and high luminescence efficiency.
“In the field of red phosphors for white LEDs, researchers have made significant progress. They produced Eu2+ and Mn2+ co-activated CaAlSiN3 red phosphors using the solid-state reaction technique in a N2 environment. The phosphors exhibit splendid thermostability and high quantum efficiency, with a quenching temperature surpassing 300 ℃ and an internal quantum efficiency of around 84.9%.”
摘要:Eu2+ and Mn2+ co-activated CaAlSiN3 red phosphors were produced using the solid-state reaction technique in a N2 environment. Excitation spectra, emission spectra, and diffuse reflection spectra were used to study the luminescence characteristics, energy gap, and thermal stability in detail. CaAlSiN3∶Eu2+ exhibits an extended emission band when stimulated with 450 nm blue light, which is caused by the 4f65d to 4f7 transition of Eu2+. Similarly, CaAlSiN3∶Mn2+ displays a wide emission band centered at 628 nm, which results from Mn2+’s transition from 4T1(4G) to 6A1(6S). When the ions of Mn2+ were combined into CaAlSiN3∶Eu2+, the photoluminescence intensity of Eu2+ was greatly boosted because there was energy transfer and co-emission between Mn2+ and Eu2+. Beyond that, CaAlSiN3∶Eu2+,Mn2+ emerges with splendid thermostability and high quantum efficiency, the quenching temperature surpasses 300 ℃, and the internal quantum efficiency is determined to be around 84.9%. The white LED was packaged with a combination of CaAlSiN3∶Eu2+,Mn2+, LuAG∶Ce3+ and a blue chip. At a warm white-light corresponding color temperature(3 009 K) with CIE coordinates(0.422 3, 0.374 8), the color rendering index Ra has reached 93.2. CaAlSiN3∶Eu2+,Mn2+ would have great application potential as a red-emitting phosphor for white LEDs.
摘要:Lead-free double perovskite materials exhibiting efficient and stable self-trapped exciton emissions hold significant promise for the advancement of next-generation solid-state lighting technologies. Novel blue-emitting phosphors (Cs2NaGdCl6∶Sb3+) were synthesized through a microwave-assisted solid-phase technique. The samples were subjected to an analysis of their crystallinity, microscopic morphology, and luminescent properties through X-ray diffractometer, scanning electron microscopy, and fluorescence spectrometer. The results reveal that the synthesized double perovskite Cs2NaGdCl6∶Sb3+ phosphors crystallize in the cubic space group Fm3m and comprise irregular particles with sizes in the tens of microns range. When excited by 336 nm light, phosphors show remarkably intense blue light emission at 460 nm, the color coordinates of samples with varying Sb3+ ion doping concentrations reside within the range of blue light. When doping concentration of Sb3+ ions exceeds 0.015, concentration quenching occurs due to the electric dipole-dipole interaction. Furthermore, the Cs2NaGd0.985Cl6∶0.015Sb3+ sample exhibits excellent thermal stability. Its integrated luminescence intensity remains at 72.6% when temperature increases to 423 K from 323 K. The research findings suggest that Sb3+ ions activated Cs2NaGdCl6 blue-emitting phosphors hold promise for applications in light-emitting diodes.
摘要:Yb3+-Er3+ co-doped all inorganic cesium lead bromide perovskite nanocrystals were prepared by hot injection method. The photoluminescence properties and crystal structure were characterized by transmission electron microscopic, fluorescence spectrum and X-ray diffraction. The experimental results show that Yb3+-Er3+ co-doped all inorganic perovskite nanocrystals emit bright green light (540 nm) and red light (646 nm) under the excitation of near-infrared light. In addition, it was found in the experimental process that the morphologies tuning of the Yb3+-Er3+ co-doped perovskite bromide nanostructures i.e. quantum dots, nanotubes, nanorods, nanoflowers, nanobelts, nanosheets have been successfully achieved by controlling reaction temperature, the temperature injected by the precursor and the proportion of the complexing agent and solvent. For Yb3+-Er3+ co-doped perovskite nanocrystals with different morphology, the phenomenon of Yb3+ sensitization Er3+ luminescence was observed under the excitation of near-infrared light, which is due to the existence of Yb3+-Er3+ energy transfer. Rare earth doping of perovskite materials can realize the up-conversion luminescence phenomenon under the excitation of near-infrared light, which is beneficial to the application of perovskite family materials in biomedical field.
摘要:Red perovskite light emitting diodes (PeLEDs) have attracted much attention for their excellent energy saving properties, which can promote plant growth, cell regeneration and metabolic processes, and show a wide range of applications in display technology, lighting systems, agricultural cultivation and medical fields. In this paper, the essential characteristics of materials used in red PeLEDs are reviewed, the current technical bottlenecks are analyzed, and a series of innovative solutions are explored to achieve high efficiency red PeLEDs. Special focus is on strategies such as co-spacer cation regulation, fine molecular engineering, efficient passivation technology, in situ inorganic ligand introduction, migration activation energy enhancement method, metastable phase crystallization optimization approach, additive induced crystal reconstruction strategy. In addition, the urgent need and challenges of developing lead-free PeLEDs with low toxicity and low environmental burden are discussed in depth, trying to improve performance of the lead-free red PeLEDs by inhibiting the oxidation tendency of Sn2+ ions, exploring new alternative elements to replace lead, and developing lead-free double perovskite materials. At the same time, the practical application cases of red PeLEDs in the specific fields such as promoting the healthy growth of indoor plants and advancing the innovation of flexible display technology. Finally, the future challenges and potential development direction in the field of red PeLEDs are prospected, which provide valuable reference and inspiration for researchers and practitioners in related fields.
“In the field of photodetectors, researchers have made significant progress. They combined 3D GaAs nanowires with 0D WS2 quantum dots to form a heterogeneous structure, which provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs nanowires.”
LI Xianshuai,LIN Fengyuan,HOU Xiaobing,LI Kexue,LIAO Lei,HAO Qun,WEI Zhipeng
摘要:The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires (NWs). We combined three-dimensional (3D) gallium arsenide nanowires with zero-dimensional (0D) WS2 quantum dot (QDs) materials in a simple and convenient way to form a heterogeneous structure. Various performance enhancements have been realized through the formation of type Ⅱ energy bands in heterostructures, opening up new research directions for the future development of photodetector devices. This work successfully fabricated a high-sensitivity photodetector based on WS2 QDs/GaAs NWs heterostructure. Under 660 nm laser excitation, the photodetector exhibits a responsivity of 368.07 A/W, a detectivity of 2.7×1012 Jones, an external quantum efficiency of 6.47×102%, a low-noise equivalent power of 2.27×10-17 W·Hz-1/2, a response time of 0.3 s, and a recovery time of 2.12 s. This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.
关键词:GaAs nanowires;WS2 quantum dots;photodetectors;type-Ⅱ energy band structure
摘要:Deep ultraviolet light-emitting diodes (DUV-LEDs) can be widely used in many fields such as sterilization, biochemical detection, healthcare and UV communication. Currently, the wall-plug efficiency of commercial DUV-LEDs is usually less than 5%, which leads to serious heat generation and high junction temperature, which in turn leads to a series of problems such as peak wavelength redshift, increased light decay, and shortened lifetime of the LEDs. In the context of the difficulty of improving the wall-plug efficiency, it is necessary to improve heat dissipation performance of DUV-LEDs to reduce their operating junction temperature. Thermal resistance is a direct parameter to reflect the heat dissipation performance of LEDs, which is usually affected by factors such as thermal conductive area, material thickness, and material thermal conductivity. In this paper, the effects of chip size, solder gap filling, thermal grease application and PCB materials on the thermal resistance of DUV LEDs have been intensively studied, and the thickness of the solid crystal area and the solder layer have been simulated. It has been found that increasing the size of the LED chip, filling the gap in the solder layer, applying thermal grease and replacing the Al PCB with a Cu PCB can reduce the thermal resistance of the LED. For a commercial 20 mil×20 mil 275 nm DUV-LED, the thermal resistance was reduced from 22.19 ℃/W to 12.83 ℃/W, and the chip temperature rise was reduced from 14.69 ℃ to 8.49 ℃ when operating at 25 ℃ and 0.662 W. The simulation results indicate that the LED working junction temperature decreases linearly with the reduction of the thickness of the solid crystal area or solder layer, in which the chip temperature increases by 44.82 ℃ for every 1 mm increase in the thickness of the solid crystal area, so the reduction of thermal resistance can be realized by appropriately thinning the thickness of the solid crystal area.
关键词:DUV-LED;heat dissipation performance;thermal resistance;junction temperature
摘要:A dual-wavelength thulium-doped fiber laser based on superimposed fiber Bragg grating (SI-FBG) and nonlinear polarization rotation (NPR) effect is proposed and demonstrated. Two SI-FBGs were used as wavelength-selective devices, and the central wavelengths of transmission spectrum were 1 940.48 nm and 1 942.87 nm for SI-FBG-1, and those of SI-FBG-2 were 1 940.47 nm and 1 942.83 nm, respectively. Stable single-wavelength and dual-wavelength operations were realized by suppressing the gain competition in the laser resonant cavity based on the NPR effect. Experimentally, the switchable single-wavelength operation was determined to be 1 940.47 nm and 1 942.87 nm, respectively. The optical signal-to-noise ratio was higher than 37.1 dB and the wavelength drifts and power fluctuations were less than 0.1 nm and 0.67 dB within 60-min, respectively. In addition, the simultaneous output of 1 940.47 nm and 1 942.87 nm was attained by adjusting the polarization controller (PC) in the resonant cavity. There were no obvious wavelength shifts during the test, and the power fluctuations were less than 0.6 dB.
摘要:Luminescent solar concentrator (LSC), as a new potential solar technology to achieve low cost electricity, has attracted wide attention, and it is the key to popularize the technique to select suitable fluorescent substrate and waveguide medium with excellent optical property. Up to now, most researchers focus on the improvement of optical properties of fluorescent substrates, but there are few reports on the performance optimization of optical waveguide medium. Here, a crystalline carbon dots (CDs) was synthesized by one-step microwave method using two precursors of phthalic acid and phthalenediamine. Since the CDs can emit green fluorescence and has a large Stokes shift between absorption and emission spectra, it is suitable as a fluorescent substrate for a new type of solar concentrator. In addition, highly transparent polyurethane (PU) films were prepared by prepolymer method, and their optical properties were studied as optical waveguide medium for LSC. By introducing sulfur element, the refractive indexes of these films were increased from 1.483 to 1.547, which directly led to a 41% increase in the photoelectric conversion efficiency of the PU film-based LSC device encapsulated with the prepared CDs as the fluorescent matrix. The results not only confirm the feasibility of PU as optical waveguide medium, but also provide experimental basis for the research method of improving optical transmission by increasing the refractive index of optical waveguide medium.
关键词:crystalline carbon dots;waveguide medium;refractive index;luminescent solar concentrator;photoelectric conversion efficiency
“In the field of luminescent metal nanoclusters, researchers have made significant progress. They have developed a stable single-chain antibody (scFv57R-ATS) for fabricating luminescent gold nanoclusters (AuNCs@scFv57R-ATS), which can quickly and sensitively detect rabies virus in living cells. This study lays a foundation for the construction of metal nanocluster fluorescent probes for antigen targeting and therapy.”
摘要:The fragile antibody leads to a great challenge as a scaffold to fabricate the luminescent metal nanoclusters using one-pot method. This study presents a stable single-chain anti-body (scFv57R-ATS) for the fabrication of luminescent gold nanoclusters(AuNCs@scFv57R-ATS) and a quick, sensitive rabies virus detection in living cells. In this paper, AuNCs@scFv57R-ATS was designed to specifically recognize antigen RV in modified HeLa cells, which promoted the demonstration of metal nanocluster fluorescent probes for antigen targeting and therapy.
摘要:Hydrogen peroxide (H2O2), a member of small-molecule reactive oxygen species (ROS), plays vital roles in normal physiological activities and the occurrence of many diseases. In this work, a novel fluorescent probe was synthesized with the 2‑(2′‑hydroxyaryl) benzothiazoles (HBT) as the fluorophores and 4-nitrophenyl acetate moiety as the reaction sites. The probe 1 exhibited a high sensitivity for H2O2 with the detection limit of 1.26 μmol/L, and displayed a good selectivity for H2O2 over other reactants such as ROS, amino acids, and various ions and anions. Through high-performance liquid chromatography (HPLC) analysis, the probe’s recognition mechanism was based on the oxidation of the α-keto ester group and the hydrolysis of the ester moiety to release the fluorophore HBT. Moreover, probe 1 has low cytotoxicity and cell permeability, and was successfully applied to bioimaging analysis of H₂O₂ within HeLa cells, confirming its feasibility and practicality for H₂O₂ detection at the cellular level.