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Luminescent Down‐Conversion Semiconductor Quantum Dots and Aligned Quantum Rods for Liquid Crystal Displays
摘要： Herein, emerging applications of luminescent semiconductor nanocrystals are addressed, such as quantum dots and quantum rods as down-conversion materials used in liquid crystal displays (LCD). Their precisely tunable emission wavelengths and narrow emission bandwidths offer high color purity resulting in a wide color gamut with vivid colors for LCDs. Anisotropic materials, such as quantum rods, have the additional advantage of polarized emission, which can bring a significant improvement to the efficiency of LCD displays. The basic optical properties of these nanomaterials are considered, with a focus on quantum rods, and the challenges and progress in their assembly are discussed. Different techniques for quantum rod alignment are introduced such as shear-oriented, electric field and magnetic field assisted assembly, mechanical rubbing, stretching, and electrospinning. The photoalignment approach allows for an easy arrangement of quantum rods in-plane, and the implications of this method to patterning are considered. Different configurations of LCDs utilizing semiconductor quantum dots and quantum rods as down-conversion layers are also presented, and the potential applications that are enabled by the wide range of emerging materials are highlighted.
关键词： quantum dots,liquid crystal displays,photoalignment,quantum rods,luminescent semiconductor nanocrystals,down-conversion materials,polarized emission
更新于2025-09-19 17:13:59
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Light Generation in Lead Halide Perovskite Nanocrystals: LEDs, Color Converters, Lasers, and Other Applications
摘要： Facile solution processing lead halide perovskite nanocrystals (LHP-NCs) exhibit superior properties in light generation, including a wide color gamut, a high flexibility for tuning emissive wavelengths, a great defect tolerance and resulting high quantum yield; and intriguing electric feature of ambipolar transport with moderate and comparable mobility. As a result, LHP-NCs have accomplished great achievements in various light generation applications, including color converters for lighting and display, light-emitting diodes, low threshold lasing, X-ray scintillators, and single photon emitters. Herein, the considerable progress that has been made thus far is reviewed along with the current challenges and future prospects in the light generation applications of LHP-NCs.
关键词： perovskite light generation nanocrystals
更新于2025-09-19 17:13:59
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Permanent photodoping of plasmonic gallium-ZnO nanocrystals
摘要： Donor dopants in oxide semiconductors are compensated not only by valuable electrons but also by other point defects, leading to a decrease in electric conductivity and infrared absorption. We demonstrate that the electron compensation mechanism in Ga doped ZnO nanocrystals can be promoted by photodoping. Unexpectedly, the electrons from photodoping are stable in the open air for months.
关键词： photodoping,infrared absorption,plasmonic,electron compensation,gallium-ZnO nanocrystals
更新于2025-09-19 17:13:59
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Transferrable thin film of ultrasonically exfoliated MoSe2 nanocrystals for efficient visible-light photodetector
摘要： Two-dimensional transition metal dichalcogenides (2D TMDC’s) materials are the impactful candidates in nanotechnology for diverse applications such as electrocatalyst, sensing and energy storage. Many efforts have been accomplished to solve the problem of green production with the scaling of TMDCs materials. Here we demonstrated the two-step method including electrophoresis deposition (EPD) and direct transfer of MoSe2 nanocrystals (NCs) thin film for fabricating visible-light photodetector. High-resolution transmission electron microscopy and atomic force microscopy show that the liquid exfoliated MoSe2 NCs exhibits good crystalline nature with multi-layered thickness. Raman spectra, UV-Visible spectra, and X-ray photoelectron spectroscopy confirm the presence of 2H-phase of MoSe2 NCs. EPD deposited thin film is detached by dipping into the water and transferred onto the etched ITO substrate. Ag/MoSe2 NCs/ITO photodetector is fabricated which demonstrated the excellent performance in the visible range and demonstrate remarkable values of responsivity, EQE (%) and specific detectivity of 566 mAW-1, 155 % and 3.69 × 1011 Jones. Considering our results, the fabrication technique along with the photoresponse application of TMDC NCs presented here is the innovative and efficient way for developing the large-area optoelectronic devices.
关键词： MoSe2 nanocrystals,Liquid-phase exfoliation,Electrophoresis,Visible-light photodetector
更新于2025-09-19 17:13:59
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Fundamental Limit of the Emission Linewidths of Quantum Dots: An Ab Initio Study of CdSe Nanocrystals
摘要： The emission linewidth of a semiconducting nanocrystal (NC) significantly affects the performance in light-emitting applications but its fundamental limit is still elusive. Herein we analyze exciton-phonon coupling (EPC) from Huang-Rhys (HR) factors using ab initio calculations, and compute emission line shapes of CdSe NCs. When surface traps are absent, acoustic modes are found to dominate EPC. The computed linewidths are mainly determined by the size of NCs, being largely insensitive to the shape and crystal structure. Linewidths obtained in this work are much smaller than most measurements on the homogeneous linewidth, but they are consistent with a CdSe/CdxZn1?xSe (core/shell) NC [Park et al. Nat. Mater. 2019, 18, 249-255]. Based on this comparison, it is concluded that the large linewidths in most experiments originated from internal fields by surface (or interface) traps or quasi-type Ⅱ band alignment that amplify EPC. Thus, the present results on NCs with ideal passivation provide the fundamental minimum of homogeneous linewidths, indicating that only the CdSe/CdxZn1?xSe NC has achieved this limit through well-controlled synthesis of the shell structure. To further verify the role of internal fields, we model NCs with charged surface defects. We find that the internal field significantly increases HR factors and linewidths, in reasonable agreements with experiments on single cores. By revealing the fundamental limit of emission linewidths of quantum dots, this work will pave the way to engineering quantum dots with ultrasharp spectrum.
关键词： nanocrystals,photoluminescence,homogeneous linewidth,exciton-phonon coupling,surface traps,density functional theory,electroluminescence,quantum dots
更新于2025-09-19 17:13:59
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Self-assembled pearl-necklace patterned upconverting nanocrystals with highly efficient blue and ultraviolet emission: femtosecond laser based upconversion properties
摘要： This work reports new findings on the formation of a pearl-necklace pattern in self-assembled upconverting nanocrystals (UCN-PNs) which exhibit strong upconversion emission under an NIR excitation source of a femtosecond laser (Fs-laser). Each nano-necklace consists of several upconversion nanoparticles (UCNPs) having a size ca. 10 ± 1 nm. UCN-PNs are arranged in a self-organized manner to form necklace type chains with an average length of 140 nm of a single row of nanoparticles. Furthermore, UCN-PNs are comprised of UCNPs with an average interparticle separation of ca. 4 nm in each of the nanonecklace chains. Interestingly, these UCN-PNs exhibit high energy upconversion especially in the UV region on interaction with a 140 Fs-laser pulse duration at 80 MHz repetition rate and intense blue emission at 450 nm on interaction with a 900 nm excitation source is obtained. The preparation of self-assembled UCNPs is easy and they are very stable for a longer period of time. The emission (fluorescence/luminescence) intensity is very high which can make them unique in innumerable industrial and bio-applications such as for disease diagnosis and therapeutic applications by targeting the infected cells with enhanced efficiency.
关键词： blue and ultraviolet emission,Self-assembled,upconverting nanocrystals,femtosecond laser,pearl-necklace patterned
更新于2025-09-16 10:30:52
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Impact of composition and ex-situ laser irradiation on the structure and optical properties of As-S-based films synthesized by PECVD
摘要： Synthesis of amorphous chalcogenide As-S-based films with arsenic content from 35 to 55 at. % by a PECVD method is achieved. The composition-structure-optical properties relationship is revealed. Varying the composition of the films from As35S65 to As55S45 is accompanied by a change of the dominant structural units: from AsS3/2 pyramids to cage-like As4S4 and As4S3 units, causing a considerable decrease of the optical band gap from 2.42 to 1.87 eV. It has been found out that modification by a focused laser irradiation (473 nm) leads to formation of micro/nanocrystalline inclusions feasible for applications in medicine, optoelectronics and integrated optics. The type of inclusions depends on the dominant structural units of the initial films. In case of the As55S45 film appearance of the dimorphite crystalline phase (α-As4S3) is observed. The ex-situ laser modification of the As-S films leads to appearance of a photoluminescence emission, and its maximum position shifts from 1.8 to 2.05 eV depending on the initial film stoichiometry.
关键词： Optical properties,Arsenic sulfide,Chalcogenide films,Nanocrystals formation,PECVD
更新于2025-09-16 10:30:52
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Electronic doping-enabled transition from n- to p-type conductivity over Au@CdS core–shell nanocrystals toward unassisted photoelectrochemical water splitting
摘要： Here we show a novel strategy for tailoring the synergistic electrical properties of metal@semiconductor hybrid nanocrystals (HNCs) based on cation exchange-enabled electronic doping. As a demonstration, the conductive nature of Au@CdS core–shell HNCs was changed from n- to p-type by introducing Cu dopants into the CdS shell. The dependence of the conductivity type on the dopant concentration in the HNCs is disclosed by combined photoelectrochemical (PEC) studies. Moreover, a tandem PEC cell consisting of an undoped Au@CdS photoanode and a Cu-doped Au@CdS photocathode respectively modified with cocatalysts is fabricated, which displayed stable H2 and O2 evolution in unassisted PEC overall water splitting.
关键词： photoelectrochemical water splitting,electronic doping,cation exchange,metal@semiconductor hybrid nanocrystals
更新于2025-09-16 10:30:52
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Red-emitting CsPbBrI2/PbSe heterojunction nanocrystals with high luminescent efficiency and stability for bright light-emitting diodes
摘要： All inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals (NCs) have been endowed great promise for optoelectronic device applications. However, further practical applications of these NCs are blocked because of their poor stability. In the present work, we propose a novel strategy to synthesize highly luminescent and stable red-emitting CsPbBrI2/PbSe heterojunction nanocrystals (h-NCs) via an epitaxial solution growth method, in which lattice-matching condition between CsPbBrI2 and PbSe was satisfied, and each CsPbBrI2 NC was partially covered by PbSe in the CsPbBrI2/PbSe heterodimers. The ultrafast transient absorption (TA) and time-resolved photoluminescence (TRPL) spectroscopy revealed that incorporation of PbSe can modify surface and hence passivate the surface trap states of the CsPbBrI2 NCs, helping to enhance the photoluminescence quantum yields (PLQY) (up to 83.4%) of these CsPbBrI2/PbSe h-NCs. First-principle calculations based on DFT confirmed that the significantly improved stability of these CsPbBrI2/PbSe h-NCs was attributed to the strong chemical bonding of selenium atoms of PbSe and lead atoms of PbX2-terminated surface from CsPbBrI2. Thin films of these CsPbBrI2/PbSe h-NCs can maintain bright red PL brightness and cubic phase even after 15-day storage under a high humidity condition. Benefiting from the performances of high stability and luminescent efficiency, these red-emitting CsPbBrI2/PbSe h-NCs have a positive implication for bright light-emitting diodes (LEDs).
关键词： nanocrystals,stability,heterojunction,light-emitting diodes,CsPbBrI2/PbSe
更新于2025-09-16 10:30:52
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Microfibers Doped with Perovskite Nanocrystals for Ultralow-Loss Waveguides
摘要： Low loss optical waveguides have attracted intense interests as the building blocks for photonic devices and integrated circuits. Herein, we employed the all-inorganic halide perovskite nanocrystals (IHPNs) doped polymer microfibers for developing the active waveguides for the first time. We reveal that the absorption coefficient (2.6 cm-1) of the CsPbBr3 IHPNs-doped polymer fibers is one order of magnitude lower than that of traditional CdSe quantum dots (QDs)-based microfibers, which can be attributed to the much higher photoluminescence quantum yield of IHPNs. Moreover, manganese ions (Mn2+) were successfully inserted into CsPbX3 IHPNs to engineer the Stokes shift and eliminate the reabsorption effect. As a result, the Mn:CsPb(Br/Cl)3 IHPNs-doped polymer microfibers exhibited a record-low absorption coefficient of 0.33 cm-1. These findings reveal a great potential of perovskite nanocrystals in photonic technologies that also paves the way for solution-processed QDs in low-loss and long-range optical guiding.
关键词： Stokes shift,perovskite nanocrystals,polymer microfibers,Low-loss waveguides,ion doping
更新于2025-09-16 10:30:52