scholarly journals Photon upconversion through triplet exciton-mediated energy relay

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sanyang Han ◽  
Zhigao Yi ◽  
Jiangbin Zhang ◽  
Qifei Gu ◽  
Liangliang Liang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
High Performance ◽  
Technology Development ◽  
Upconversion Luminescence ◽  
Excitation Power ◽  
Host Lattice ◽  
Energy Migration ◽  
Triplet Exciton ◽  
Long Distance ◽  
Experimental Conditions

AbstractExploration of upconversion luminescence from lanthanide emitters through energy migration has profound implications for fundamental research and technology development. However, energy migration-mediated upconversion requires stringent experimental conditions, such as high power excitation and special migratory ions in the host lattice, imposing selection constraints on lanthanide emitters. Here we demonstrate photon upconversion of diverse lanthanide emitters by harnessing triplet exciton-mediated energy relay. Compared with gadolinium-based systems, this energy relay is less dependent on excitation power and enhances the emission intensity of Tb3+ by 158-fold. Mechanistic investigations reveal that emission enhancement is attributable to strong coupling between lanthanides and surface molecules, which enables fast triplet generation (<100 ps) and subsequent near-unity triplet transfer efficiency from surface ligands to lanthanides. Moreover, the energy relay approach supports long-distance energy transfer and allows upconversion modulation in microstructures. These findings enhance fundamental understanding of energy transfer at molecule-nanoparticle interfaces and open exciting avenues for developing hybrid, high-performance optical materials.

scholarly journals Multiband emission from single β-NaYF4(Yb,Er) nanoparticles at high excitation power densities and comparison to ensemble studies

Nano Research ◽  
2021 ◽  
Author(s):  
Florian Frenzel ◽  
Christian Würth ◽  
Oleksii Dukhno ◽  
Frédéric Przybilla ◽  
Lisa M. Wiesholler ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Single Particle ◽  
Near Infrared ◽  
Upconversion Luminescence ◽  
Excited State Absorption ◽  
High Energy ◽  
Excitation Power ◽  
Relaxation Processes ◽  
Excitation Power Density ◽  
Radiative Relaxation

AbstractEnsemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core-shell β-NaYF4:Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb3+ and 1% or 3% Er3+ performed over a P regime of 6 orders of magnitude reveal an increasing contribution of the emission from high energy Er3+ levels at P > 1 kW/cm2. This changes the overall emission color from initially green over yellow to white. While initially the green and with increasing P the red emission dominate in ensemble measurements at P < 1 kW/cm2, the increasing population of higher Er3+ energy levels by multiphotonic processes at higher P in single particle studies results in a multitude of emission bands in the ultraviolet/visible/near infrared (UV/vis/NIR) accompanied by a decreased contribution of the red luminescence. Based upon a thorough analysis of the P-dependence of UCL, the emission bands activated at high P were grouped and assigned to 2–3, 3–4, and 4 photonic processes involving energy transfer (ET), excited-state absorption (ESA), cross-relaxation (CR), back energy transfer (BET), and non-radiative relaxation processes (nRP). This underlines the P-tunability of UCNP brightness and color and highlights the potential of P-dependent measurements for mechanistic studies required to manifest the population pathways of the different Er3+ levels.

Photoluminescence Kinetics Model of P-Type GaAs:Nd

1996 ◽  
Vol 422 ◽  
Author(s):  
U. K. Saha ◽  
H. J. Lozykowski
Keyword(s):  
Experimental Data ◽  
Energy Transfer ◽  
Rare Earth ◽  
Excitation Power ◽  
Host Lattice ◽  
The Core ◽  
Type Semiconductor ◽  
P Type ◽  
Kinetics Of ◽  
Good Agreement

AbstractIn this work we have developed a model for the kinetics of the energy transfer from the host lattice to the core states of rare earth (RE) centers. We have derived a set of kinetics differential equations of RE luminescence in p-type semiconductor. Numerically computed rise and decay time of RE luminescence as a function of excitation power shows good agreement with the experimental data obtained for p-type GaAs:Nd.

scholarly journals Metal Ions Doping for Boosting Luminescence of Lanthanide-Doped Nanocrystals

2020 ◽  
Vol 8 ◽  
Author(s):  
Shihao Pei ◽  
Xiaoqian Ge ◽  
Lining Sun
Keyword(s):  
Energy Transfer ◽  
Metal Ion ◽  
Upconversion Luminescence ◽  
Relevant Literature ◽  
Electric Dipole Transition ◽  
Host Lattice ◽  
High Signal ◽  
Luminescence Efficiency ◽  
Emission Color ◽  
Wide Range

With the developing need for luminous materials with better performance, lanthanide-doped nanocrystals have been widely studied for their unique luminescence properties such as their narrow bandwidth emission, excellent chemical stability, and photostability, adjustable emission color, high signal-to-background ratio, deeper tissue penetration with less photo-damage, and low toxicity, etc., which triggered enthusiasm for research on the broad applications of lanthanide-doped nanocrystals in bioimaging, anti-counterfeiting, biosensing, and cancer diagnosis and treatment. Considerable progress has been made in the past few decades, but low upconversion luminescence efficiency has been a hindrance in achieving further progress. It is necessary to summarize the recently relevant literature and find solutions to improve the efficiency. The latest experimental and theoretical studies related to the deliberate design of rare earth luminescent nanocrystals have, however, shown the development of metal ion-doped approaches to enhance the luminescent intensity. Host lattice manipulation can enhance the luminescence through increasing the asymmetry, which improves the probability of electric dipole transition; and the energy transfer modulation offers a reduced cross-relaxation pathway to improve the efficiency of the energy transfer. Based on the mechanisms of host lattice manipulation and energy transfer modulation, a wide range of enhancements at all wavelengths or even within a particular wavelength have been accomplished with an enhancement of up to a hundred times. In this mini review, we present the strategy of metal ion-doped lanthanide nanocrystals to cope with the issue of enhancing luminescence, overview the advantages and tricky challenges in boosting the luminescence, and provide a potential trend of future study in this field.

Sub-20nm Device Voltage-Sensitive SRAM Characterization and Failure Analysis

2018 ◽  
Author(s):  
Seng Nguon Ting ◽  
Hsien-Ching Lo ◽  
Donald Nedeau ◽  
Aaron Sinnott ◽  
Felix Beaudoin
Keyword(s):  
Failure Analysis ◽  
High Performance ◽  
Yield Loss ◽  
Technology Development ◽  
High Density ◽  
High K ◽  
Yield Learning ◽  
Oxide Deposition ◽  
Edge Profile ◽  
High K Dielectric

Abstract With rapid scaling of semiconductor devices, new and more complicated challenges emerge as technology development progresses. In SRAM yield learning vehicles, it is becoming increasingly difficult to differentiate the voltage-sensitive SRAM yield loss from the expected hard bit-cells failures. It can only be accomplished by extensively leveraging yield, layout analysis and fault localization in sub-micron devices. In this paper, we describe the successful debugging of the yield gap observed between the High Density and the High Performance bit-cells. The SRAM yield loss is observed to be strongly modulated by different active sizing between two pull up (PU) bit-cells. Failure analysis focused at the weak point vicinity successfully identified abnormal poly edge profile with systematic High k Dielectric shorts. Tight active space on High Density cells led to limitation of complete trench gap-fill creating void filled with gate material. Thanks to this knowledge, the process was optimized with “Skip Active Atomic Level Oxide Deposition” step improving trench gap-fill margin.

Micro-Thermal Field-Flow Fractionation

2002 ◽  
Vol 67 (11) ◽  
pp. 1596-1608 ◽  
Author(s):  
Josef Janča
Keyword(s):  
High Performance ◽  
Thermal Field ◽  
Temperature Drop ◽  
Point Of View ◽  
Constant Field ◽  
Field Flow Fractionation ◽  
Operational Mode ◽  
Experimental Conditions ◽  
Standard Size ◽  
Flow Fractionation

The effect of miniaturization of the separation channel on the performance of thermal field-flow fractionation (TFFF) is substantiated theoretically. The experiments carried out under carefully chosen experimental conditions proved the high performance of the separation of polymers within an extended range of molar masses from relatively low up to ultrahigh-molar-mass (UHMM) samples. The new micro-TFFF allows to achieve high resolution when applying constant field force operation, it makes easy the programming of the temperature drop which is an advantageous operational mode from the point of view of the time of analysis, and it extends considerably the range of perfectly controlled temperature of the cold wall due to a substantial decrease in the heat energy flux compared with standard size channels.

scholarly journals High-performance quasi-2D perovskite light-emitting diodes: from materials to devices

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Li Zhang ◽  
Changjiu Sun ◽  
Tingwei He ◽  
Yuanzhi Jiang ◽  
Junli Wei ◽  
...  
Keyword(s):  
Energy Transfer ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Structural Characteristics ◽  
Quantum Yields ◽  
Research Directions ◽  
Light Emitting ◽  
Perovskite Materials ◽  
Quantum Confinement Effects ◽  
Semiconducting Properties

AbstractQuasi-two-dimensional (quasi-2D) perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation light-emitting diodes (LEDs). The outstanding optical properties originate from their structural characteristics. In particular, the inherent quantum-well structure endows them with a large exciton binding energy due to the strong dielectric- and quantum-confinement effects; the corresponding energy transfer among different n-value species thus results in high photoluminescence quantum yields (PLQYs), particularly at low excitation intensities. The review herein presents an overview of the inherent properties of quasi-2D perovskite materials, the corresponding energy transfer and spectral tunability methodologies for thin films, as well as their application in high-performance LEDs. We then summarize the challenges and potential research directions towards developing high-performance and stable quasi-2D PeLEDs. The review thus provides a systematic and timely summary for the community to deepen the understanding of quasi-2D perovskite materials and resulting LED devices.

scholarly journals How Relevant Is It to Use Mineral Proxies to Mimic the Atmospheric Reactivity of Natural Dust Samples? A Reactivity Study Using SO2 as Probe Molecule

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 282
Author(s):  
Darya Urupina ◽  
Manolis N. Romanias ◽  
Frederic Thevenet
Keyword(s):  
High Performance ◽  
Real Life ◽  
Complex Mixtures ◽  
Experimental Conditions ◽  
The Real ◽  
Atmospheric Processes ◽  
Real Effects ◽  
Mineral Aerosols ◽  
Life Impact ◽  
Reactivity Study

The experimental investigation of heterogeneous atmospheric processes involving mineral aerosols is extensively performed in the literature using proxy materials. In this work we questioned the validity of using proxies such as Fe2O3, FeOOH, Al2O3, MgO, CaO, TiO2, MnO2, SiO2, and CaCO3 to represent the behavior of complex mixtures of minerals, such as natural desert and volcanic dusts. Five volcanic dusts and three desert dusts were compared to a number of metal oxides, commonly used in the literature to mimic the behavior of desert dusts in the ability to form sulfites and sulfates on the surface exposed to SO2 gas. First, all samples were aged at room temperature, atmospheric pressure, under controlled experimental conditions of 175 ppm SO2 for 1 h under 30% of relative humidity. Second, they were extracted with 1% formalin and analyzed by High-Performance Liquid Chromatography (HPLC) to quantify and compare the amount of sulfites and sulfates formed on their surfaces. It was evidenced that under the experimental conditions of this study neither one selected pure oxide nor a mixture of oxides can adequately typify the behavior of complex mixtures of natural minerals. Therefore, to evaluate the real-life impact of natural dust on atmospheric processes it is of vital importance to work directly with the natural samples, both to observe the real effects of desert and volcanic dusts and to evaluate the relevancy of proposed proxies.

scholarly journals Down-Shifting in the YAM: Ce3+ + Yb3+ System for Solar Cells

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2753
Author(s):  
Bartosz Fetliński ◽  
Sebastian Turczyński ◽  
Michał Malinowski ◽  
Paweł Szczepański
Keyword(s):  
Energy Transfer ◽  
Emission Intensity ◽  
Potential Application ◽  
Single Photon ◽  
Solar Spectrum ◽  
Excitation Power ◽  
Photovoltaic Devices ◽  
Photoluminescence Properties ◽  
System A ◽  
Down Conversion

In this work, we investigate Ce3+ to Yb3+ energy transfer in Y4Al2O9 (YAM) for potential application in solar spectrum down-converting layers for photovoltaic devices. Photoluminescence properties set, of 10 samples, of the YAM host activated with Ce3+ and Yb3+ with varying concentrations are presented, and the Ce3+ to Yb3+ energy transfer is proven. Measurement of highly non-exponential luminescence decays of Ce3+ 5d band allowed for the calculation of maximal theoretical quantum efficiency, of the expected down-conversion process, equal to 123%. Measurements of Yb3+ emission intensity, in the function of excitation power, confirmed the predominantly single-photon downshifting character of Ce3+ to Yb3+ energy transfer. Favorable location of the Ce3+ 5d bands in YAM makes this system a great candidate for down-converting, and down-shifting, luminescent layers for photovoltaics.

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