Two-Junction GaAs/Ge Cells With Three Terminals for PV and CPV Applications

2009 ◽  
Vol 1165 ◽  
Author(s):  
Mahieddine Emziane
Keyword(s):  
Power Output ◽  
Near Infrared ◽  
Incident Light ◽  
Solar Spectrum ◽  
Junction Device ◽  
High Power Output ◽  
Optimal Current ◽  
Simulated Concentration ◽  
Potential Applications ◽  
Double Junction

AbstractThe present investigation deals with a two-junction device having GaAs as the top cell and Ge for the bottom cell on a Ge substrate. Compared with the conventional two-terminal device configuration, three terminals avoid the loss due to current mismatching between the cells, and the resistance loss originating from the tunnel junction between the cells. Device structures were investigated and optimized with regard to the thicknesses and doping levels of both top and bottom active junctions that lead to the highest device performance. Due to the split of the incident solar spectrum between GaAs and Ge cells, the latter only receives the light to which the former is transparent (mainly in the near infrared) and therefore behaves differently from a single-junction Ge cell. Optimal current-voltage and power-voltage characteristics were generated for individual cells together with the corresponding device PV parameters. The predictions show that an extended spectral coverage is achieved leading to an enhanced overall power output from the devices. The potential applications of these devices in conventional as well as concentrator PV were assessed and discussed as a function of the simulated concentration ratio of the incident light under AM1.5 illumination conditions. We have shown that a relatively thin double-junction GaAs/Ge device can achieve a remarkably high power output.

scholarly journals Recent Advances in Fabrication of Flexible, Thermochromic Vanadium Dioxide Films for Smart Windows

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2674
Author(s):  
Jongbae Kim ◽  
Taejong Paik
Keyword(s):  
Thin Films ◽  
Energy Saving ◽  
Near Infrared ◽  
Solar Spectrum ◽  
Smart Windows ◽  
Space Group ◽  
Practical Applications ◽  
Flexible Polymer ◽  
Recent Advances ◽  
Potential Applications

Monoclinic-phase VO2 (VO2(M)) has been extensively studied for use in energy-saving smart windows owing to its reversible insulator–metal transition property. At the critical temperature (Tc = 68 °C), the insulating VO2(M) (space group P21/c) is transformed into metallic rutile VO2 (VO2(R) space group P42/mnm). VO2(M) exhibits high transmittance in the near-infrared (NIR) wavelength; however, the NIR transmittance decreases significantly after phase transition into VO2(R) at a higher Tc, which obstructs the infrared radiation in the solar spectrum and aids in managing the indoor temperature without requiring an external power supply. Recently, the fabrication of flexible thermochromic VO2(M) thin films has also attracted considerable attention. These flexible films exhibit considerable potential for practical applications because they can be promptly applied to windows in existing buildings and easily integrated into curved surfaces, such as windshields and other automotive windows. Furthermore, flexible VO2(M) thin films fabricated on microscales are potentially applicable in optical actuators and switches. However, most of the existing fabrication methods of phase-pure VO2(M) thin films involve chamber-based deposition, which typically require a high-temperature deposition or calcination process. In this case, flexible polymer substrates cannot be used owing to the low-thermal-resistance condition in the process, which limits the utilization of flexible smart windows in several emerging applications. In this review, we focus on recent advances in the fabrication methods of flexible thermochromic VO2(M) thin films using vacuum deposition methods and solution-based processes and discuss the optical properties of these flexible VO2(M) thin films for potential applications in energy-saving smart windows and several other emerging technologies.

Near-infrared quantum cutting of Dy3+, Ho3+–Yb3+ and Er3+–Yb3+-doped Ca10K(PO4)7 phosphors

2014 ◽  
Vol 07 (04) ◽  
pp. 1450047 ◽  
Author(s):  
Jia Zhang ◽  
Cheng Jiang
Keyword(s):  
Near Infrared ◽  
Spectral Characteristics ◽  
Solar Spectrum ◽  
Solid State Reaction Method ◽  
Excitation Spectra ◽  
Energy Transfers ◽  
Potential Applications ◽  
Nir Emission ◽  
Quantum Cutting ◽  
First Time

Dy 3+, Ho 3+– Yb 3+ and Er 3+– Yb 3+-doped Ca 10 K ( PO 4)7 phosphors were prepared by solid-state reaction method, and their luminescence properties of near-infrared (NIR) quantum cutting (QC) were investigated for the first time. The Rietveld refinement performed for the X-ray diffractometer (XRD) data indicates the obtained samples are single-phase. From the excitation spectra, it can be seen that the energy transfers from Ho 3+ to Yb 3+, and from Er 3+ to Yb 3+ occur. The Dy 3+, Ho 3+– Yb 3+ and Er 3+– Yb 3+ co-doped Ca 10 K ( PO 4)7 samples all exhibit NIR emission peaks in the QC processes, and their spectral characteristics are agreement with the corresponding NIR QC mechanisms. The NIR QC properties of the as-prepared samples indicate the potential applications in modifying the solar spectrum to enhance the efficiency of silicon solar cells.

Multipodal and Multilayer TiO2 Nanotube Arrays: Hierarchical Structures for Energy Harvesting and Sensing

2013 ◽  
Vol 1552 ◽  
pp. 29-34 ◽  
Author(s):  
Arash Mohammadpour ◽  
Samira Farsinezhad ◽  
Ling-Hsuan Hsieh ◽  
Karthik Shankar
Keyword(s):  
Solar Cells ◽  
Light Absorption ◽  
Near Infrared ◽  
Incident Light ◽  
Solar Spectrum ◽  
Hierarchical Structures ◽  
Quantum Yields ◽  
Nanotube Arrays ◽  
Liquid Junction ◽  
Excitonic Solar Cells

AbstractOur ability to fabricate multipodal and multilayer TiO2 nanotube arrays enables us to increase performance and functionality in light harvesting devices such as excitonic solar cells and photocatalysts. Using a combination of simulations and experiments, we show that multilayer nanotube arrays enable photon management in the active toward enhancing the absorption and utilization of incident light. We show that the simultaneous utilization of TiO2 nanotubes with large (∼450 nm) and small (∼80 nm) diameters in stacked multilayer films increased light absorption and photocurrent in solar cells. Such enhanced light absorption is particularly desirable in the near-infrared region of the solar spectrum in which most excitonic solar cells suffer from poor quantum efficiencies and for blue photons at the TiO2 band-edge where significant room exists for improvement of photocatalytic quantum yields. Under AM 1.5 one sun illumination, multilayer nanotube arrays afforded us an approximately 20% improvement in photocurrent over single layer nanotube array films of the same thickness for N-719 sensitized liquid junction solar cells. Also, the possibility of multipodal TiO2 nanotube growth with different electrolyte recipes is presented.

Design and Evaluation of the Fresnel-Lens Based Solar Concentrator System Through a Statistical-Algorithmic Approach

2018 ◽  
Author(s):  
Hassan Qandil ◽  
Weihuan Zhao
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Incident Light ◽  
Thermal Analyses ◽  
Solar Spectrum ◽  
Chromatic Aberration ◽  
Fresnel Lens ◽  
Optimum Number ◽  
Solar Concentrator ◽  
Receiver System

A novel non-imaging Fresnel-lens-based solar concentrator-receiver system has been investigated to achieve high-efficiency photon and heat outputs with minimized effect of chromatic aberrations. Two types of non-imaging Fresnel lenses, a spot-flat lens and a dome-shaped lens, are designed through a statistical algorithm incorporated in MATLAB. The algorithm optimizes the lens design via a statistical ray-tracing methodology of the incident light, considering the chromatic aberration of solar spectrum, the lens-receiver spacing and aperture sizes, and the optimum number of prism grooves. An equal-groove-width of the Poly-methyl-methacrylate (PMMA) prisms is adopted in the model. The main target is to maximize ray intensity on the receiver’s aperture, and therefore, achieve the highest possible heat flux and output concentration temperature. The algorithm outputs prism and system geometries of the Fresnel-lens concentrator. The lenses coupled with solar receivers are simulated by COMSOL Multiphysics. It combines both optical and thermal analyses for the lens and receiver to study the optimum lens structure for high solar flux output. The optimized solar concentrator-receiver system can be applied to various devices which require high temperature inputs, such as concentrated photovoltaics (CPV), high-temperature stirling engine, etc.

High-energy organic group-induced spectrally pure upconversion emission in novel zirconate-/hafnate-based nanocrystals

CrystEngComm ◽  
2015 ◽  
Vol 17 (37) ◽  
pp. 7169-7174 ◽  
Author(s):  
Xianghong He ◽  
Bing Yan
Keyword(s):  
Pump Power ◽  
Near Infrared ◽  
Incident Light ◽  
Upconversion Emission ◽  
High Energy ◽  
Single Band ◽  
Organic Group ◽  
Red Fluorescence

A series of novel fluoride-based nanophosphors (NPs) exhibiting spectrally pure upconversion (UC) red fluorescence upon near-infrared (980 nm) excitation. The single-band deep-red UC luminescence feature of K3MF7:Yb3+,Er3+ (M = Zr, Hf) NPs is independent of the doping levels of Yb3+–Er3+ and the pump power of incident light.

Design of a novel photoelectrochemical enzymatic biofuel cell with high power output under visible light

2021 ◽  
pp. 134037
Author(s):  
Xinzhou Huang ◽  
Long Ren ◽  
Chunyun Jiang ◽  
Xiangxiang Han ◽  
Xiaoshuang Yin ◽  
...  
Keyword(s):  
Visible Light ◽  
High Power ◽  
Power Output ◽  
Biofuel Cell ◽  
Enzymatic Biofuel Cell ◽  
High Power Output

Thermal Analysis and Experiment of a Ka-Band High-Power Output Window

2021 ◽  
Author(s):  
Quanhong Lu ◽  
Jianxun Wang ◽  
Xinjie Li ◽  
Yixin Wan ◽  
Wei Jiang ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
High Power ◽  
Power Output ◽  
Output Window ◽  
Ka Band ◽  
High Power Output
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