A5028471863- solar cell performance optimization
- Chalcogenide Semiconductor Thin Films
- Semiconductor Quantum Structures and Devices
- Thermal Radiation and Cooling Technologies
- Silicon and Solar Cell Technologies
- Nanowire Synthesis and Applications
- Advanced Thermodynamics and Statistical Mechanics
- Electrocatalysts for Energy Conversion
- Quantum Dots Synthesis And Properties
- Solar Thermal and Photovoltaic Systems
- Photovoltaic System Optimization Techniques
- Thin-Film Transistor Technologies
- Advanced Photocatalysis Techniques
- Semiconductor materials and interfaces
- Perovskite Materials and Applications
- Semiconductor materials and devices
- Electron and X-Ray Spectroscopy Techniques
- Physics of Superconductivity and Magnetism
- Atmospheric Ozone and Climate
- Ga2O3 and related materials
- 3D IC and TSV technologies
- Optical Coatings and Gratings
- Advanced battery technologies research
- Advanced Semiconductor Detectors and Materials
- Near-Field Optical Microscopy
National Renewable Energy Laboratory
2016-2025
University of Ottawa
2024
Colorado School of Mines
2023-2024
Sonic Concepts (United States)
2023
Phoenix (United States)
2023
Arizona State University
2023
University of Wisconsin–Madison
2023
Lawrence Berkeley National Laboratory
2023
Stanford University
2005-2022
University of California, Santa Barbara
2022
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...
We report the fabrication and measurement of thermophotovoltaic (TPV) cells with efficiencies >40%, which is a record high TPV efficiency first experimental demonstration high-bandgap tandem cells. was determined by simultaneous electric power output heat dissipation from device via calorimetry. The are two-junction devices comprising high-quality III-V materials band gaps between 1.0 1.4 eV that optimized for emitter temperatures 1900-2400{\deg}C. exploit concept band-edge spectral...
Thermophotovoltaic power conversion utilizes thermal radiation from a local heat source to generate electricity in photovoltaic cell. It was shown recent years that the addition of highly reflective rear mirror solar cell maximizes extraction luminescence. This, turn, boosts voltage, enabling creation record-breaking efficiency. Now we report can be used create thermophotovoltaic systems with unprecedented high This reflects low-energy infrared photons back into source, recovering their...
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"...
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...
Abstract The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system–PV modules for portable applications that operate at greater than 50% efficiency. We are integrating the design with solar cell design, and have entered previously unoccupied space. Our approach driven by proven quantitative models integration of these designs. Optical systems efficiency an 93% device results under ideal dichroic splitting optics summing to 42·7 ± 2·5% described. Copyright ©...
The storage of liquid silicon above 2000 °C and multi-junction photovoltaics enable affordable, geographically independent grid level energy storage.
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....
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%...
The inverted metamorphic solar cell has highly tunable bandgaps, in part due to the subcells. Using phosphide-based compositionally graded buffers, we show a wide variety of GaInAs cells, ranging bandgap from 1.2 0.7 eV. These subcells are all high quality and can be used for multijunction designs. cells with 0.70 eV bandgaps developed using an InAsP buffer that extends beyond InP lattice constant, allowing access additional 2 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Abstract High‐efficiency solar cells are essential for high‐density terrestrial applications, as well space and potentially vehicle applications. The optimum bandgap the spectrum lies beyond absorption range of a traditional dual junction GaInP/GaAs cell, with bottom GaAs cell having higher energy than necessary. Lower bandgaps can be achieved multiple quantum wells (QWs), but such pathway requires advanced management epitaxial growth conditions in order to useful. Strain‐balanced...
H2 production by direct photoelectrochemical (PEC) water splitting has remained unachievable commercially, mainly due to rapid failure at the interface between photoabsorber(s) and catalyst(s). PEC devices made from multijunction III–V semiconductors with platinum group metal (PGM) catalysts have yielded impressive initial solar-to-H2 (STH) efficiency >19%, which rapidly corrodes in aqueous electrolytes. Here, TiO2/TiN layers were fused create a bifunctional GaInP2/GaAs tandem photoabsorber...
Through a detailed study of scaling near the magnetic field-tuned superconductor-to-insulator transition in strongly disordered films, we find that results for variety materials can be collapsed onto single phase diagram. The data display two clear branches, one with weak disorder and an intervening metallic phase, other strong disorder. Along branch, resistance at critical point approaches $R_Q = h/4e^2$ is consistent quantum percolation, therefore predictions dirty boson model.
Abstract We have designed, fabricated, and tested a small, integrated photovoltaic module comprised of two separately‐contacted, high efficiency, multijunction solar cells non‐imaging optics that both concentrate spectrally split the incoming light. This hybrid design allows us to individually optimize tandem optical elements. The system has measured including packaging losses but not power combination losses, 38.5 ± 1.9% under AM1.5 direct terrestrial spectrum. internal light by factor...