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Significant Enhancement in Quantum Dot Light-Emitting Device Stability via a Cascading Hole Transport Layer
摘要： This work investigates the effect of the hole transport layer (HTL) on the stability of electroluminescent quantum dot light-emitting devices (QDLEDs). The electroluminescence half-life (LT50) of QDLEDs can be improved by 25x through the utilization of a cascading HTL (CHTL) structure with consecutive steps in highest occupied molecular orbital energy level. Using this approach, a LT50 of 864,000 hours (for an initial luminance of 100 cd m-2) is obtained for red QDLEDs using a conventional core/shell QD emitter. The CHTL primarily improves QDLED stability by shifting excessive hole accumulation away from the QD/HTL interface and toward the inter-layer HTL/HTL interfaces. The wider electron-hole recombination zone in the CHTL for electrons that have leaked from the QD layer results in less HTL degradation at the QD/HTL interface. This work highlights the significant influence of the HTL on QDLED stability and represents the longest LT50 for a QDLED based on the conventional core/shell QD structure.
关键词： quantum dot,EL stability,exciton-polaron interactions,QDLED,organic hole transport layer,exciton-induced degradation
更新于2025-09-23 15:19:57
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Controllable movement of single-photon source in multifunctional magneto-photonic structures
摘要： Quantum dot (QD) coupling in nanophotonics has been widely studied for various potential applications in quantum technologies. Micro-machining has also attracted substantial research interest due to its capacity to use miniature robotic tools to make precise controlled movements. In this work, we combine fluorescent QDs and magnetic nanoparticles (NPs) to realize multifunctional microrobotic structures and demonstrate the manipulation of a coupled single-photon source (SPS) in 3D space via an external magnetic field. By employing the low one photon absorption (LOPA) direct laser writing (DLW) technique, the fabrication of 2D and 3D magneto-photonic devices containing a single QD is performed on a hybrid material consisting of colloidal CdSe/CdS QDs, magnetite Fe3O4 NPs, and SU-8 photoresist. Two types of devices, contact-free and in-contact structures, are investigated to demonstrate their magnetic and photoradiative responses. the coupled SPS in the devices is driven by the external magnetic field to perform different movements in a 3D fluidic environment. The optical properties of the single QD in the devices are characterized.
关键词： Quantum dot,direct laser writing,single-photon source,magnetic nanoparticles,magneto-photonic structures
更新于2025-09-23 15:19:57
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Numerical simulation of PbSe quantum dots doped fiber ring laser with 1.7 <i>?μ</i> m wavelength
摘要： A lead selenide quantum dot-doped fiber ring laser operating at 1.7 μm wavelength is proposed and investigated by numerical simulation for the first time. Its temporal and spectral characteristics under different simulation parameters are presented. The fact that the obtained temporal profiles using different simulation parameters are largely different is observed and analyzed. These results offer us a new practical path to generate a 1.7 μm continuous-wave and pulsed laser for deep biomedical application.
关键词： fibre laser,1.7 μm wavelength,lead selenide (PbSe) quantum dot
更新于2025-09-23 15:19:57
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Photoluminescence Loss and Recovery of ?±-CsPbI3 Quantum Dots Originated from Chemical Equilibrium Shift of Oleylammonium
摘要： α-CsPbI3 perovskite quantum dots (PQDs) have great potentials in red-emitting LED and solar cell applications. However, their instability with quick photoluminescence loss with time greatly limits their development. In this study, we found that the nonluminous aged α-CsPbI3 PQDs instantly regained fluorescence emission after a surface treatment with trioctylphosphine. Meanwhile, this surface treatment also worked on fresh α-CsPbI3 PQDs to enhance photoluminescence emission. The structures and compositions of fresh and aged PQDs before and after surface treatment were analyzed in detail. We demonstrated that a surface chemical equilibrium shift mechanism involving oleylammonium led to the PL loss and recovery of α-CsPbI3 PQDs. This chemical equilibrium shift also played an important role in other PQD stabilities against long term storage, temperature, UV irradiation and ethanol, which were all significantly improved after treatment. The treated α-CsPbI3 PQDs were phase stable for more than 6 months. Oleic acid and oleylamine are common ligands used in PQD syntheses; this study shall promote the understanding of PQD surface chemistry and the preparation of stable α-CsPbI3 PQDs.
关键词： photoluminescence loss,oleylammonium,recovery,CsPbI3,Perovskite quantum dot
更新于2025-09-23 15:19:57
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Multiplexed Single-Photon Source Based on Multiple Quantum Dots Embedded within a Single Nanowire
摘要： Photonics-based quantum information technologies require efficient, high emission rate sources of single photons. Position-controlled quantum dots embedded within a broadband nanowire waveguide provide a fully scalable route to fabricating highly efficient single photon sources. However, emission rates for single photon devices are limited by radiative recombination lifetimes. Here we demonstrate a multiplexed single photon source based on a multi-dot nanowire. Using epitaxially grown nanowires, we incorporate multiple energy-tuned dots, each optimally positioned within the nanowire waveguide, and providing single photons with high efficiency. This linear scaling of the single photon emission rate with number of emitters is demonstrated using a five-dot nanowire with an average multiphoton emission probability of < 4% when excited at saturation. This represents the first ever demonstration of multiple single photon emitters deterministically incorporated in a single photonic device, and is a major step towards achieving GHz single photon emission rates from a scalable multi-quantum dot system.
关键词： nanowire,single photon source,multiplexing,quantum dot
更新于2025-09-23 15:19:57
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Rapid Optical Spin Initialization of a Quantum Dot in the Voigt Geometry Coupled to a Two-Dimensional Semiconductor
摘要： We study the interaction of a quantum dot in the Voigt con?guration with a laser pulse and particularly analyze the potential for rapid spin initialization by putting the quantum dot near a molybdenum disul?de (MoS2) monolayer. The MoS2 monolayer in?uences the spontaneous decay rates of the quantum dot, leading to anisotropically enhanced decay rates, for the quantum dot’s electric dipole moments parallel and perpendicular to the layer. By solving the relevant density matrix equations, we ?nd that high spin initialization ?delity is obtained at short times. The ?delity is signi?cantly higher than when the quantum dot is in free-space vacuum. We examine two different cases of the interaction of the quantum dot with the applied optical ?eld. First, we use a continuous wave laser ?eld and determine for various quantum dot—MoS2 layer distances the ?eld strength that leads to acceptable ?delity levels. The effect of the quality of the MoS2 material on the ?delity of spin initialization is also examined. We also study the interaction of the quantum dot with a laser pulse and apply numerical optimal control to obtain the time-dependent ?eld strength, which leads to maximum ?nal ?delity for short time intervals. The latter approach gives bene?cial results in comparison to the continuous wave ?eld excitation.
关键词： spin initialization,quantum dot,Voigt geometry,optical pumping,Purcell effect,optimal control,spin dynamics
更新于2025-09-23 15:19:57
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Photoelectric process in GaAs quantum dot
摘要： We study the photoelectric process in single electron charged spherical GaAs/Ga1-yAlyAs quantum dot. The effective mass approximation is used with the finite potential at the dot matrix interface including the effect of self-energy. The total cross section of photoelectric process is investigated with the variation of incident photon energy and the molar concentration y of Al in Ga1-yAlyAs matrix material.
关键词： Quantum dot,Effective mass approximation,Finite potential,Photoelectric process
更新于2025-09-23 15:19:57
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Enhancing electrostatic coupling in silicon quantum dot array by dual gate oxide thickness for large-scale integration
摘要： We propose a structure with word/bit line control for a two-dimensional quantum dot array, which allows random access for arbitrary quantum dots with a small number of control signals. To control multiple quantum dots with a single signal, every quantum dot should have a wide operating voltage allowance to overcome the property variations. We fabricate two-dimensional quantum dot arrays using silicon-complementary-metal-oxide-semiconductor technology with an alternating dual-standard gate oxide thickness. The quantum dots are designed to have an allowable operating voltage window of 0.2 V to control the number of electrons, which is a window one order of magnitude wider than that of previous works. The proposed structure enables both easy fabrication and operation for multiple quantum dots and will pave the way for practical use of large-scale quantum computers.
关键词： electrostatic coupling,dual gate oxide thickness,quantum dot array,large-scale integration,silicon-complementary-metal-oxide-semiconductor technology
更新于2025-09-23 15:19:57
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Optimized Operation of Quantum-Dot Intermediate-Band Solar Cells Deduced from Electronic Transport Modeling
摘要： Study of the physics of quantum electronic transport has not tackled the problems raised by quantum-dot intermediate-band solar cells. Our study shows that this physics imposes design rules for the intersubband transition. We develop an analytical model that correctly treats, from a quantum point of view, the trade-off between the absorption, the recombination, and the electronic transport occurring in this transition. Our results clearly indicate that it is essential to control the transit rate between the excited state of the quantum dot and the embedding semiconductor. For that, we propose assuming the dot in a tunnel shell whose main characteristics can be obtained by a simple analytical formula. Moreover, we show that in a realistic case, the energy transition needs to be larger than only 0.27 eV to obtain a quasi-Fermi-level-splitting. This quite small value designates the quantum-dot solar cell as a serious candidate to be an efficient intermediate-band solar cell. This work gives a framework to design efficient intersubband transitions and opens new opportunities for quantum-dot intermediate-band solar cells.
关键词： quantum-dot,intersubband transition,electronic transport modeling,intermediate-band solar cells,quasi-Fermi-level-splitting
更新于2025-09-23 15:19:57
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Quantum dot exciton dephasing by Coulomb interaction: A fermionic analog of the independent boson model
摘要： The time evolution of a quantum dot exciton in Coulomb interaction with wetting layer carriers is treated using an approach similar to the independent boson model. The role of the polaronic unitary transform is played by the scattering matrix, for which a diagrammatic, linked cluster expansion is available. Similarities and differences to the independent boson model are discussed. A numerical example is presented.
关键词： independent boson model,exciton,scattering matrix,Coulomb interaction,quantum dot
更新于2025-09-23 15:19:57