High Performance Photocathodes with 50% Quantum Efficiency

2005 ◽  
Vol 480-481 ◽  
pp. 445-448 ◽  
Author(s):  
P.D. Townsend ◽  
R.J. Downey ◽  
S.W. Harmer ◽  
A.N. Cormack ◽  
R. Mcalpine
Keyword(s):  
Quantum Efficiency ◽  
Spectral Range ◽  
High Performance ◽  
High Efficiency ◽  
High Transparency ◽  
Operating Range

Multialkali photocathodes are used from 200 to 850 nm, but high transparency at longer wavelengths reduces the quantum efficiencies. Theoretically, routes to enhance absorption could achieve high efficiency over most of this spectral range. Realisations of some of the concepts have been successfully attempted leading to quantum efficiencies of ~50%, with examples from 200 to 750 nm. Improvement factors of up to 50 times occur by ~900 nm, giving an extension of the useful wavelength operating range.

scholarly journals Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth

2019 ◽  
Author(s):  
Baiquan Liu ◽  
Yemliha Altintas ◽  
Lin Wang ◽  
Sushant Shendre ◽  
Manoj Sharma ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Shell Growth ◽  
Light Emitting ◽  
Hot Injection ◽  
Key Factor

<p> Colloidal quantum wells (CQWs) are regarded as a new, highly promising class of optoelectronic materials thanks to their unique excitonic characteristics of high extinction coefficient and ultranarrow emission bandwidth. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind compared with other types of LEDs (e.g., organic LEDs, colloidal quantum-dot LEDs, and perovskite LEDs). Herein, for the first time, the authors show high-efficiency CQW-LEDs reaching close to the theoretical limit. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition- and device- engineering, the CQW-LEDs using CdSe/Cd<sub>0.25</sub>Zn<sub>0.75</sub>S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23,490 cd m<sup>-2</sup>, extremely saturated red color with the Commission Internationale de L’Eclairage coordinates of (0.715, 0.283) and stable emission are obtained. The findings indicate that HIS grown CQWs enable high-performance solution-processed LEDs, which may pave the path for CQW-based display and lighting technologies.</p>

scholarly journals Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth

2019 ◽  
Author(s):  
Baiquan Liu ◽  
Yemliha Altintas ◽  
Lin Wang ◽  
Sushant Shendre ◽  
Manoj Sharma ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Shell Growth ◽  
Light Emitting ◽  
Hot Injection ◽  
Key Factor

<p> Colloidal quantum wells (CQWs) are regarded as a new, highly promising class of optoelectronic materials thanks to their unique excitonic characteristics of high extinction coefficient and ultranarrow emission bandwidth. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind compared with other types of LEDs (e.g., organic LEDs, colloidal quantum-dot LEDs, and perovskite LEDs). Herein, for the first time, the authors show high-efficiency CQW-LEDs reaching close to the theoretical limit. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition- and device- engineering, the CQW-LEDs using CdSe/Cd<sub>0.25</sub>Zn<sub>0.75</sub>S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23,490 cd m<sup>-2</sup>, extremely saturated red color with the Commission Internationale de L’Eclairage coordinates of (0.715, 0.283) and stable emission are obtained. The findings indicate that HIS grown CQWs enable high-performance solution-processed LEDs, which may pave the path for CQW-based display and lighting technologies.</p>

The Development of High Performance Centrifugal Compressor Using CFD and Other Considerations

2017 ◽  
Author(s):  
C. Xu ◽  
M. Muller
Keyword(s):  
Power Distribution ◽  
High Performance ◽  
High Efficiency ◽  
Low Noise ◽  
Field Application ◽  
Air Separation ◽  
Operating Range ◽  
Design Considerations ◽  
Reliable Design ◽  
Air Compression

Air compression is one of the most important processes of air separation. Reliable design, higher performance, low noise, no resonant frequencies in the operating range and economic to manufacture are the goals of compressor design. Although CFD has been widely used in the compressor designs, there are many design considerations need to be addressed during the design. In this paper, the detailed design considerations for compressor configuration, power distribution for each stage, and possible field application issues are discussed in detail. The aerodynamic and structural optimization using CFD and FEA are performed to obtain a high efficiency and wide operating range compressor stage with for robust operation. The new compressor development process addressed in this paper provides the basic design guidance for future new compressor development.

Numerical Study on the Range Enhancement of a Centrifugal Compressor With a Ring Groove System

2011 ◽  
Author(s):  
ChiYong Park ◽  
YoungSeok Choi ◽  
KyoungYong Lee ◽  
JoonYong Yoon
Keyword(s):  
Centrifugal Compressor ◽  
High Performance ◽  
High Efficiency ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Low Flow ◽  
Ring Groove ◽  
Guide Vanes ◽  
Operating Range ◽  
Surge Margin

This paper presents a numerical study of casing treatments on a centrifugal compressor in order to improve stability and the surge margin. High efficiency, a high pressure ratio, and a wide operating range are required for a high-performance centrifugal compressor. A ring groove casing treatment is effective for flow range enhancement in centrifugal compressors. In the present study, compressor performance was analyzed according to the ring groove location and the results were compared with the case without a ring groove. The effect of guide vanes in the ring groove was also investigated. Four more variants of grooves were modeled and simulated using computational fluid dynamics (CFD) in order to optimize the groove location. The numerical analysis was carried out using a commercial code ANSYS-CFX program. The simulation results showed that the ring groove increased the operating range of the compressor. The ring groove with guide vanes improved both the compressor’s performance at low flow rates and improved the compressor’s surge margin.

scholarly journals Power and Spectral Range Characteristics for Optical Power Converters

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4395
Author(s):  
Simon Fafard ◽  
Denis Masson ◽  
Jan-Gustav Werthen ◽  
James Liu ◽  
Ta-Chung Wu ◽  
...  
Keyword(s):  
Laser Diode ◽  
Spectral Range ◽  
High Performance ◽  
High Efficiency ◽  
Power Converters ◽  
Electrical Power ◽  
Optical Power ◽  
Power Outputs ◽  
External Loads ◽  
Power Class

High-performance optical power converters (OPCs) enable isolated electrical power and power beaming applications at new wavelengths and higher output powers. Broadcom’s vertical epitaxial heterostructure architecture (VEHSA) multi-junction OPCs permit optical-to-electrical conversion at high efficiency and at manageable external loads. This study provides details of how the power outputs have been extended from <1 W to a power class at ~3 W and another class at >20 W. The work also provides details of how the spectral range options have been extended from 800–830 nm to other key laser diode wavelengths such as 960–990 nm and 1500–1600 nm.

High-Performance Hardware Interpolation Architecture for High Efficiency Video Coding Decoder

2016 ◽  
Vol 11 (9) ◽  
pp. 764
Author(s):  
Lella Aicha Ayadi ◽  
Nihel Neji ◽  
Hassen Loukil ◽  
Mouhamed Ali Ben Ayed ◽  
Nouri Masmoudi
Keyword(s):  
Video Coding ◽  
High Performance ◽  
High Efficiency ◽  
High Efficiency Video Coding

scholarly journals Investigation on the La Replacement and Little Additive Modification of High-Performance Permanent Magnetic Strontium-Ferrite

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1034
Author(s):  
Ching-Chien Huang ◽  
Chin-Chieh Mo ◽  
Guan-Ming Chen ◽  
Hsiao-Hsuan Hsu ◽  
Guo-Jiun Shu
Keyword(s):  
High Performance ◽  
Single Phase ◽  
Permanent Magnets ◽  
High Efficiency ◽  
Cobalt Content ◽  
Preparation Condition ◽  
Milling Process ◽  
Experimental Parameters ◽  
La Substitution ◽  
Hard Magnets

In this work, an experiment was carried out to investigate the preparation condition of anisotropic, Fe-deficient, M-type Sr ferrite with optimum magnetic and physical properties by changing experimental parameters, such as the La substitution amount and little additive modification during fine milling process. The compositions of the calcined ferrites were chosen according to the stoichiometry LaxSr1-xFe12-2xO19, where M-type single-phase calcined powder was synthesized with a composition of x = 0.30. The effect of CaCO3, SiO2, and Co3O4 inter-additives on the Sr ferrite was also discussed in order to obtain low-temperature sintered magnets. The magnetic properties of Br = 4608 Gauss, bHc = 3650 Oe, iHc = 3765 Oe, and (BH)max = 5.23 MGOe were obtained for Sr ferrite hard magnets with low cobalt content at 1.7 wt%, which will eventually be used as high-end permanent magnets for the high-efficiency motor application in automobiles with Br > 4600 ± 50 G and iHc > 3600 ± 50 Oe.

New hole transport styrene polymers bearing highly π-extended conjugated side-chain moieties for high-performance solution-processable thermally activated delayed fluorescence OLEDs

2021 ◽  
Vol 12 (11) ◽  
pp. 1692-1699
Author(s):  
Ji Hye Lee ◽  
Jinhyo Hwang ◽  
Chai Won Kim ◽  
Amit Kumar Harit ◽  
Han Young Woo ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Delayed Fluorescence ◽  
Hole Transport ◽  
Side Chain ◽  
Solution Processed ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Turn On ◽  
Solution Processable

New polystyrene-based polymers with high π-extended hole transport pendants were synthesized to obtain a low turn-on voltage and high efficiency in solution-processed green TADF-OLEDs.

scholarly journals Neighborhood Energy Modeling and Monitoring: A Case Study

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3716
Author(s):  
Francesco Causone ◽  
Rossano Scoccia ◽  
Martina Pelle ◽  
Paola Colombo ◽  
Mario Motta ◽  
...  
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Early Stage ◽  
Energy Performance ◽  
Monitoring Plan ◽  
Performance Targets ◽  
Carrier Energy ◽  
Zero Carbon ◽  
Energy Grid

Cities and nations worldwide are pledging to energy and carbon neutral objectives that imply a huge contribution from buildings. High-performance targets, either zero energy or zero carbon, are typically difficult to be reached by single buildings, but groups of properly-managed buildings might reach these ambitious goals. For this purpose we need tools and experiences to model, monitor, manage and optimize buildings and their neighborhood-level systems. The paper describes the activities pursued for the deployment of an advanced energy management system for a multi-carrier energy grid of an existing neighborhood in the area of Milan. The activities included: (i) development of a detailed monitoring plan, (ii) deployment of the monitoring plan, (iii) development of a virtual model of the neighborhood and simulation of the energy performance. Comparisons against early-stage energy monitoring data proved promising and the generation system showed high efficiency (EER equal to 5.84), to be further exploited.

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