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- 摘要
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- 实验方案
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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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Interplay between various active regions and the interband transition for AlGaN-based deep-ultraviolet light-emitting diodes to enable a reduced TM-polarized emission
摘要： Al-rich AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) have a low light extraction efficiency, especially when the emission wavelength is shorter than 280 nm, and this is partially because of the dominant transverse-magnetic polarized light. Our results show that the transverse-electric (TE) polarized light can be obtained even if the emission wavelength becomes even shorter by reducing the quantum well thickness. The ultrathin quantum well enables the enhanced TE-polarized emission that arises from the redistributed subbands for holes. On the contrary to the common belief, we observe a blueshift for the emission wavelength when the AlN composition in the quantum barrier increases. The internal quantum efficiency (IQE) for DUV LEDs with ultrathin quantum wells is no longer determined by the quantum-confined Stark effect, while quantum barrier with high AlN composition is vitally important to improve the electron injection efficiency and thus enhance the IQE.
关键词： quantum well,AlGaN,quantum barrier,internal quantum efficiency,deep-ultraviolet,TE-polarized emission,light-emitting diodes
更新于2025-09-12 10:27:22
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12.1: <i>Invited Paper:</i> Polarization control and optical efficiency improvement of light emitted from OLED using liquid crystalline luminophores
摘要： Highly circularly polarized (CP) light is generated by using a twisted conjugated polymer structure with a small amount of chiral molecules as the light emitting layer of the OLED. It is confirmed that the luminous efficiency is increased by 60% compared to the conventional OLED structure.
关键词： organic light emitting diodes,conjugated polymer,polarized emission,chiral dopant,Circular polarization
更新于2025-09-11 14:15:04
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Triplet exciton fine structure in Pt-rich polymers studied by circularly polarized emission under high magnetic field
摘要： Incorporating heavy atoms into polymer chains represents an effective way to generate emissive triplets. Here we used magneto-optical emission spectroscopy up to 17.5 Tesla for studying the fine structure of the triplet exciton in a series of Pt-rich π-conjugated polymers with various intrachain Pt concentrations. We found that their phosphorescence emission band shows substantial field-induced circular polarization (FICPO) up to 50% with an unusual, nonmonotonic field dependence at cryogenic temperature. From the field-induced energy splitting between left and right circularly polarized phosphorescence we obtained the effective g factor of triplet exciton varying in the range of ?0.13-0.85, which depends on the Pt concentration in the polymer chains. The FICPO of triplet emission originates from the population difference in spin sublevels, which is determined by thermal equilibrium subjected to spin-orbit coupling (SOC), exchange, and Zeeman interactions. Surprisingly we also observed FICPO in the fluorescence emission that results from the singlet-triplet interaction caused by the strong SOC. From these results we extracted the various interaction parameters that describe the exciton fine structure in these Pt-contained compounds.
关键词： Pt-rich polymers,high magnetic field,circularly polarized emission,spin-orbit coupling,triplet exciton
更新于2025-09-11 14:15:04