A5001249709- solar cell performance optimization
- Semiconductor Quantum Structures and Devices
- Chalcogenide Semiconductor Thin Films
- GaN-based semiconductor devices and materials
- Semiconductor materials and devices
- Nanowire Synthesis and Applications
- Semiconductor materials and interfaces
- Silicon and Solar Cell Technologies
- Quantum Dots Synthesis And Properties
- Perovskite Materials and Applications
- Thermal Radiation and Cooling Technologies
- Photonic and Optical Devices
- Quantum and electron transport phenomena
- Advanced Semiconductor Detectors and Materials
- Ga2O3 and related materials
- Spectroscopy and Quantum Chemical Studies
- Semiconductor Lasers and Optical Devices
- Photovoltaic System Optimization Techniques
- Solar Thermal and Photovoltaic Systems
- Photochemistry and Electron Transfer Studies
- Advanced Thermodynamics and Statistical Mechanics
- Thin-Film Transistor Technologies
- Advancements in Semiconductor Devices and Circuit Design
- Surface and Thin Film Phenomena
- Integrated Circuits and Semiconductor Failure Analysis
National Renewable Energy Laboratory
2016-2025
Phoenix (United States)
2023
Colorado School of Mines
2022-2023
Sonic Concepts (United States)
2023
Arizona State University
2023
Institut für Solarenergieforschung
2021
Washington State University
2018
Southern Nursing Research Society
2007
University at Buffalo, State University of New York
1999
University of Wisconsin–Madison
1993-1997
We present evidence for a strong interaction between the conduction band and narrow resonant formed by nitrogen states in $\mathrm{Ga}{}_{1\ensuremath{-}x}\mathrm{In}{}_{x}\mathrm{N}{}_{y}\mathrm{As}{}_{1\ensuremath{-}y}$ alloys. The leads to splitting of into two subbands reduction fundamental gap. An anticrossing extended $\mathrm{Ga}{}_{1\ensuremath{-}x}\mathrm{In}{}_{x}\mathrm{As}$ matrix localized is used model interaction. Optical transitions associated with energy minima...
A photovoltaic conversion efficiency of 40.8% at 326 suns concentration is demonstrated in a monolithically grown, triple-junction III–V solar cell structure which each active junction composed an alloy with different lattice constant chosen to maximize the theoretical efficiency. The semiconductor was grown by organometallic vapor phase epitaxy inverted configuration 1.83 eV Ga.51In.49P top lattice-matched GaAs substrate, metamorphic 1.34 In.04Ga.96As middle junction, and 0.89 In.37Ga.63As...
The authors demonstrate a thin, Ge-free III–V semiconductor triple-junction solar cell device structure that achieved 33.8%, 30.6%, and 38.9% efficiencies under the standard 1sun global spectrum, space concentrated direct spectrum at 81suns, respectively. consists of 1.8eV Ga0.5In0.5P, 1.4eV GaAs, 1.0eV In0.3Ga0.7As p-n junctions grown monolithically in an inverted configuration on GaAs substrates by organometallic vapor phase epitaxy. lattice-mismatched junction was last graded GaxIn1−xP...
The self-absorption of radiated photons increases the minority carrier concentration in semiconductor optoelectronic devices such as solar cells. This so-called photon recycling leads to an increase external luminescent efficiency, fraction internally that are able escape through front surface. An increased efficiency turn correlates with open-circuit voltage and ultimately conversion efficiency. We develop a detailed ray-optical model calculates Voc for real, non-idealized cells, accounting...
We demonstrate 1.81 eV GaInP solar cells approaching the Shockley-Queisser limit with 20.8% conversion efficiency, 8% external radiative and 80–90% internal efficiency at one-sun AM1.5 global conditions. Optically enhanced voltage through photon recycling that improves light extraction was achieved using a back metal reflector. This optical enhancement realized currents when non-radiative Sah-Noyce-Shockley junction recombination current reduced by placing of cell in higher band gap AlGaInP...
Sunlight absorption within the electrolyte impacts performance and design of high-efficiency tandem PEC devices as evidenced by detailed balance calculations.
We propose practical six-junction (6J) inverted metamorphic multijunction (IMM) concentrator solar cell designs with the potential to exceed 50% efficiency using moderately high quality junction materials. demonstrate top three junctions and their monolithic integration lattice matched GaAs 2.1-eV AlGaInP, 1.7-eV AlGaAs or GaInAsP, 1.4-eV external radiative efficiencies >0.1%. tunnel peak tunneling current >400 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
In order to realize a clean energy society by using renewable energies, high-performance solar cells are very attractive proposition. The development of offers promising pathway toward achieving high power per unit cost for many applications. As state-of-the-art single-junction approaching the Shockley–Queisser limit 32%–33%, an important strategy raise efficiency further is stacking cell materials with different bandgaps absorb colors spectrum. III–V semiconductor provide relatively...
Combining two or more junctions into a tandem solar cell promises to deliver leap in power conversion efficiency that will help sustain continued growth installed photovoltaic (PV) capacity. Although tandems are now on the roadmaps of many PV manufacturers, much work remains before they ready for mass deployment. Accelerating their development requires advances fronts. In this article, we outline fundamentals and status PV, considering multiple technology pairings architectures. We then...
III–N–V semiconductors are promising materials for use in next-generation multijunction solar cells because these can be lattice matched to substrates such as GaAs, Ge and Si, with a range of bandgaps that complementary those other III–V semiconductors. Several potentially high-efficiency photovoltaic device designs using discussed. The main roadblock the development cell devices is poor minority-carrier transport materials. present understanding material properties GaInNAs GaAs GaNPAs Si reviewed.
We report electroreflectance spectra for a series of ${\mathrm{GaAs}}_{1\ensuremath{-}x}{\mathrm{N}}_{x}$ samples with $x<0.03$. For all samples, the fundamental band gap transition $({E}_{0})$ and from spin-orbit split-off valence $({E}_{0}+{\ensuremath{\Delta}}_{0})$ are observed. $x\ensuremath{\ge}0.008$, an additional $({E}_{+})$ is With increasing nitrogen content, increase in ${E}_{+}$ linear in, nearly equal to, reduction indicative nitrogen-induced level repulsion. The directly...
A dramatic increase of the conduction band electron mass in a nitrogen-containing III–V alloy is reported. The found to be strongly dependent on nitrogen content and concentration with value as large 0.4m0 In0.08Ga0.92As0.967N0.033 6×1019 cm−3 free electrons. This more than five times larger effective GaAs comparable typical heavy hole masses compounds. results provide critical test fully confirm predictions recently proposed anticrossing model electronic structure III–N–V alloys.
The alloy GaInAsN has great potential as a lower-band-gap material lattice matched to GaAs, but there is little understanding of what causes its poor optoelectronic properties and why these improve with annealing. This study provides information about the structural changes that occur when annealed. Fourier transform infrared spectra exhibit two primary features: triplet at ∼470 cm−1 (Ga–N stretch) or three bands ∼3100 (N–H stretch). change in Ga–N stretch absorption can be explained if...
Combining a Si solar cell with high-bandgap top reduces the thermalization losses in short wavelength and enables theoretical 1-sun efficiencies far over 30%. We have investigated fabrication optimization of Si-based tandem cells 1.8-eV rear-heterojunction GaInP cells. The III–V heterojunction subcells were fabricated separately joined by mechanical stacking using electrically insulating optically transparent interlayers. Our GaInP/Si dual-junction achieved certified cumulative efficiency...
The assumption of superposition or linearity photocurrent with solar flux is widespread for calculations and measurements cells. well-known effect luminescent coupling in multijunction cells has also been assumed to be linear excess current. Here we show significant non-linearities III-V propose a simple model based on competition between radiative nonradiative processes the junction explain these non-linearities. We demonstrate technique accurately measuring photocurrents under specified...
The emission of light from each junction in a series-connected multijunction solar cell both complicates and elucidates the understanding its performance under arbitrary conditions. Bringing together many recent advances this understanding, we present general 1-D model to describe luminescent coupling that arises voltage-driven electroluminescence voltage-independent photoluminescence nonideal junctions include effects such as Sah-Noyce-Shockley (SNS) recombination with n ≠ 2, Auger...
We present results for quadruple-junction inverted metamorphic (4J-IMM) devices under the concentrated direct spectrum and analyze limitations to performance. The integrate lattice-matched subcells with rear heterojunctions, as well lattice-mismatched low threading dislocation density. To interconnect subcells, thermally stable tunnel junctions are used, a GaAsSb/GaInAs junction between subcells. A broadband antireflection coating is front metal grid designed high concentration operation....
Uncontrolled spectral mismatch of laboratory light sources and inappropriate area definitions induce vast inaccuracies for solar-to-hydrogen efficiency measurement reporting.
The performance of dual-junction solar cells with a Si bottom cell has been investigated both theoretically and experimentally. Simulations show that adding top junction an energy bandgap 1.6 -1.9 eV to standard silicon enables efficiencies over 38%. Currently, junctions GaInP (1.8 eV) are the most promising as they can achieve 1-sun 20.8% [1]. We fabricated mechanically stacked, four terminal GaInP/Si tandem using transparent adhesive between subcells. These devices achieved efficiency 27%...