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Quantum dot material engineering boosting quantum dot sensitized solar cells efficiency over 13%
摘要： The intrinsic electronic structure and crystalline quality of quantum dot (QD) light-harvesting materials are among the primary reasons in determining the photovoltaic performance of resulting QD sensitized solar cells (QDSCs). Undoubtedly, exploiting appropriate high-quality QDs is a crucial route to improve the performance of QDSCs. In order to reduce the density of trap state defects, a ZnSe shell layer with wider bandgap is overgrown around the light-harvesting star material Zn-Cu-In-Se (ZCISe) alloy QDs to form the type-I core/shell structured ZCIS/ZnSe. Through this QD material engineering, average power conversion efficiency (PCE) of QDSCs was improved from 9.54% corresponding to pristine CuInSe2, to 12.49% from alloyed ZCISe, and to 13.71% for core/shell structured ZCISe/ZnSe QDs. A certified PCE of 13.49% has been obtained for the ZCIS/ZnSe QDSCs under AM 1.5G one sun irradiation. This value is a new record efficiency for QDSCs. The remarkable enhancement of photovoltaic performance for ZCIS/ZnSe-based QDSCs vs. ZCISe ones is mainly ascribed to the reduced density of trap state defects, which favours the suppression of charge recombination at photoanode/electrolyte interfaces and hence improves the photovoltage and fill factor, particularly. The steady state optical spectroscopy, diode ideality factor, transient absorption, and electrochemical impedance spectroscopy characterizations confirm that the formed type-I core/shell structure can reduce the density of trap state defects and suppress charge recombination and improve the photovoltaic performance of the resulting cells. This work demonstrates the great potential of QD material engineering in improving the photovoltaic performance of QDSCs.
关键词： sensitized solar cells,photovoltaic performance,quantum dot,ZnSe,Zn-Cu-In-Se
更新于2025-09-23 15:21:01
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Quantum Dot-Based Sensitization System for Boosted Photon Absorption and Enhanced Second Near-Infrared Luminescence of Lanthanide-Doped Nanoparticle
摘要： Efficient energy transfer is a promising strategy in overcoming the inherent limits of narrow band and weak absorption of lanthanide ions due to the nature of 4f-4f transitions. Herein, we introduce a nanoparticle-sensitized nanoparticle system where a near-infrared-emitting quantum dot (QD) is used as a sensitizer with broadband photon absorption for lanthanide-doped nanoparticle (LNP) to generate second near-infrared (NIR-II) emission. The NIR-II luminescence of Er3+-doped LNP by Ag2S QD sensitization displays an enhancement of ~17-fold in intensity and ~10-fold in brightness over bare LNP because of increased absorptivity and overall broadening of the absorption spectrum of LNP. Furthermore, QD-sensitized LNP system exhibits excellent photostability, and is able to improve the signal to noise ratio of tumor NIR-II imaging via in situ crosslinking of QD and LNP. The QD-sensitized LNP system for luminescence enhancement opens a potential avenue for efficient energy transfer in complex nanoparticle-nanoparticle systems.
关键词： Lanthanide-Doped Nanoparticle,Photon Absorption,Second Near-Infrared Luminescence,Quantum Dot,Sensitization System
更新于2025-09-23 15:21:01
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Adsorption and Cation Exchange Behavior of Zinc Sulfide (ZnS) on Mesoporous TiO2 Film and Its Applications to Solar Cells
摘要： Zinc sulfide (ZnS) was deposited onto the surface of mesoporous TiO2 film by a typical successive ionic layer adsorption and reaction (SILAR) process. By inducing a spontaneous cation exchange between ZnS and a target cation (Pb2+, Cu2+, Ag+, or Bi3+) dissolved in chemical bath when they are in contact, it was demonstrated successfully that white translucent ZnS on the substrate could be changed to brown-colored new metal chalcogenides and the amount of ZnS deposited originally by different conditions could be compared in a qualitative way with the degree of the color change. By utilizing this simple but effective process, the evolution of well-known ZnS passivation layer prepared from different chemical baths in quantum dot (QD)-sensitized solar cells could be tracked visually via checking the degree of color change of TiO2/ZnS electrodes after the induced specific cation exchange. When applied to representative CdS QD-sensitized solar cells, it was revealed clearly how the different degree and rate of ZnS deposition could affect the overall power conversion efficiency while finding an optimized passivation layer over TiO2/CdS electrode. Acetate anion-coupled Zn2+ source was observed to give a much faster deposition of ZnS passivation layer than nitrate anion one due to its higher pH-induced more favorable adsorption of Zn2+ on the surface of TiO2. As another useful application of the ZnS-based cation exchange, as-deposited ZnS was used as a template for preparing a more complex metal chalcogenide onto mesoporous TiO2 film. The ZnS-derived Sb2S3-sensitized electrode showed a promising initial result of over 1.0 % overall power conversion efficiency with a very thin ZrO2 passivation layer between TiO2 and Sb2S3.
关键词： passivation,Quantum dot-sensitizer,SILAR deposition,zinc sulfide,solar cell,cation exchange
更新于2025-09-23 15:21:01
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Bandgap-Tuned CuInS <sub/>2</sub> /ZnS Core/Shell Quantum Dots for a Luminescent Downshifting Layer in a Crystalline Silicon Solar Module
摘要： CuInS2 (CIS) quantum dots (QDs) were investigated as a luminescent downshifting (LDS) material that converts near-ultraviolet (UV) light to visible light and were applied to a single crystalline silicon (c-Si) solar module that has no spectral sensitivity in the near-UV region. The bandgap of the CIS/ZnS core/shell QDs was successfully adjusted to ~3 eV, which was adequate for the LDS layer in solar devices, by changing the molar ratio of Cu/In. CIS/ZnS/ZnS core/shell/shell QDs with 59.9% absolute photoluminescence (PL) quantum yield were prepared by the hot-injection method and embedded in ethylene vinyl acetate copolymer (EVA) resin to fabricate QD@EVA films as the LDS layer. The PL intensity of the QD@EVA films under near-UV excitation monotonically increased with increasing QD concentration. The films were attached to a commercial single c-Si solar module. The advantages and drawbacks of the films were discussed based on the results of incident photon-to-electron conversion efficiency and current-voltage curve measurements.
关键词： CuInS2/ZnS,quantum dot,nanocomposite film,solar module,nanophosphor,luminescent downshifting layer,photoluminescence
更新于2025-09-23 15:21:01
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Electromagnetically induced grating with second field quantization in spherical semiconductor quantum dots
摘要： A new approach for diffracting the weak probe beam into higher-order directions is proposed via electromagnetically induced grating in second field quantization formalism, offering a new way for implementations of quantum information with semiconductor quantum dots. The formalism of second field quantization allows describing atoms and photons as a many-body system. An induced diffraction grating is formed based on the electromagnetic induced transparency when a standing-wave coupling field is applied to a spherical quantum dot as a three-level system. Due to phase modulation, the zeroth-order light intensity becomes weak, and the first-order diffraction is improved affectedly. On the contrary, the probe beam is barely diffracted via absorption modulation. The simulation results verify that photon numbers of probe and control fields, as well as other parameters in the QD, can lead to the diffraction efficiency of phase grating to be improved. Phase diffraction grating accompanied with a high transmissivity is demonstrated, and the first-order diffraction efficiency reaches 30%. Also, the impact of QD dimensions on its optical response is investigated. This model may find potential applications in designing the semiconductor quantum dot-based photonic devices in optical communications and quantum information networks.
关键词： Electromagnetically induced grating (EIG),Semiconductor quantum dot (SQD),Second field quantization
更新于2025-09-23 15:21:01
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Dual-Emitting Quantum Dot Complex Nanoprobe for Ratiometric and Visual Detection of Hg2+ and Cu2+ ions
摘要： Herein we report the use of a dual emitting quantum dot complex (QDC; composed of blue emitting metal-methylsalicylaldimine complex being on the surface of orange emitting Mn2+-doped ZnS quantum dot) for ratiometric and visual detection of Hg2+ and Cu2+ ions - following the alterations in luminescence color, intensity ratio, chromaticity and hue of the QDC.
关键词： Hg2+ ions,Cu2+ ions,ratiometric detection,quantum dot complex,visual detection
更新于2025-09-23 15:21:01
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One-pot fabrication of mesoporous g-C3N4/NiS co-catalyst counter electrodes for quantum-dot-sensitized solar cells
摘要： The nickel sulfide (NiS) nanoparticles were anchored on the mesoporous graphitic carbon nitride (g-C3N4) by one-pot calcination with sulfur powder as sulfur source and pore-forming agent. It is the first attempt to use the g-C3N4/NiS as a counter electrode (CE) for quantum-dot-sensitized solar cells. The g-C3N4/NiS co-catalyst based on 0.74 wt% NiS loading for Sn2- reduction obtained a low interface charge transfer resistance (Rct) of 1.08 Ω. The power conversion efficiency of the QDSSC assembled with ZnSe/CdS/CdSe/ZnSe-sensitized TiO2 photoanode and g-C3N4/NiS CE is up to 5.64%, which is 3.05 times as high as that of pure g-C3N4 CE. The enhancement of cell efficiency is attributed to the synergistic effects of excellent morphology of g-C3N4 and its co-catalysis with NiS nanoparticles. The mesoporous architecture contributes a large specific surface area and fast electrolyte transfer channels, and the coupling of g-C3N4 with NiS promotes the transfer of charge between the interface g-C3N4/NiS and electrolytes. The presented strategy for fabricating mesoporous architecture with g-C3N4/NiS uses low-cost raw materials and a simple preparation method, which provides a feasible route to enhance the electrocatalytic activity of g-C3N4.
关键词： g-C3N4/NiS,electrocatalytic activity,mesoporous architecture,counter electrode,quantum-dot-sensitized solar cells
更新于2025-09-23 15:21:01
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AIP Conference Proceedings [AIP Publishing 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Bikaner, India (14a??15 October 2019)] 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Study of optical properties of Wannier-Mott exciton in spherical quantum dot in Kratzer potential
摘要： Study of optical properties of Wannier-Mott exciton in spherical quantum dot in Kratzer potential
关键词： Kratzer potential,spherical quantum dot,Wannier-Mott exciton,optical properties
更新于2025-09-23 15:21:01
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Temperature and hydrostatic pressure effects on the electronic structure, optical properties of spherical segment quantum dot/wetting layer and group velocity of light
摘要： To investigate hydrostatic pressure and temperature effects on electron energy levels of an InAs spherical segment quantum dot with wetting layer embedded in GaAs barrier, we use the finite element method to solve the Schr?dinger equation in the effective mass approximation. Results show that the ground, the first and the second excited state energies decrease (increase) as the hydrostatic pressure (temperature) increases for the constant temperature (pressure). Moreover, given the optical properties of the system interacting with two laser fields, red (blue) shifts are observed in the linear and nonlinear absorptions and dispersions for the probe pulse as the hydrostatic pressure (temperature) increases. Furthermore, as the hydrostatic pressure increases, the maximum of the group velocity of light inside the slow light frequency range increases and the slow light frequency range shifts to the lower probe frequencies.
关键词： temperature,group velocity of light,hydrostatic pressure,optical property,quantum dot/wetting layer
更新于2025-09-23 15:21:01
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Higha??efficiency quantum dot lighta??emitting diodes with blue cadmiuma??free quantum dots
摘要： We report outstanding electroluminescence properties of high-efficiency blue cadmium-free quantum dot light-emitting diodes (QD-LED). External quantum efficiency (EQE) of 14.7% was achieved for QD-LED emitting at 428 nm. Furthermore, we developed high-efficiency and narrow wavelength emission zinc selenide (ZnSe) nanocrystals emitting at 445 nm and achieved QD-LED with an EQE of 10.7%. These new QDs have great potential to be used in next-generation QD-LED display with wide color gamut.
关键词： cadmium-free,blue quantum dot,QD-LED,EQE
更新于2025-09-23 15:21:01