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A. Martí
Instituto de Energía Solar, Universidad Politécnica de Madrid

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Preprint content
Published: 23 July 2021
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We demonstrate a heterojunction bipolar transistor solar cell (HBTSC), a device that exhibits the performance of a double-junction solar cell in a more compact npn (or pnp) semiconductor structure. The HBTSC concept has the advantages of being a three-terminal device, such as low spectral sensitivity and high tolerance to non-optimal band-gap energies, while it has a lower fabrication and operation complexity than other multi-terminal architectures: it can produce independent power extraction from the two junctions without the need for extra isolating or interconnecting layers between them. The two junctions in our proof-of-concept HBTSC prototype, which is made of epitaxial GaInP/GaAs, exhibit independent current-voltage characteristics under AM1.5G illumination, with respective open-circuit voltages of 1.33 and 0.95 V. The HBTSC opens a new perspective in the understanding of multi-junction devices, and it is an excellent candidate for the application of low-cost fabrication techniques, and for the implementation of III-V-on-silicon tandems.

ACS Style

Marius Zehender; Simon Svatek; Myles Steiner; Ivan Garcia; Pablo Garcia-Linares; Emily Warren; Adele Tamboli; Antonio Martí; Elisa Antolín. GaInP/GaAs three-terminal heterojunction bipolar transistor solar cell. 2021, 1 .

AMA Style

Marius Zehender, Simon Svatek, Myles Steiner, Ivan Garcia, Pablo Garcia-Linares, Emily Warren, Adele Tamboli, Antonio Martí, Elisa Antolín. GaInP/GaAs three-terminal heterojunction bipolar transistor solar cell. . 2021; ():1.

Chicago/Turabian Style

Marius Zehender; Simon Svatek; Myles Steiner; Ivan Garcia; Pablo Garcia-Linares; Emily Warren; Adele Tamboli; Antonio Martí; Elisa Antolín. 2021. "GaInP/GaAs three-terminal heterojunction bipolar transistor solar cell." , no. : 1.

Journal article
Published: 25 December 2020 in IEEE Journal of Photovoltaics
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Intermediate band solar cells (IBSCs) pursue the increase in efficiency by absorbing below-bandgap energy photons while preserving the output voltage. Experimental IBSCs based on quantum dots (QDs) have already demonstrated that both below-bandgap photon absorption and the output voltage preservation are possible. However, the experimental work has also revealed that the below-bandgap absorption of light is weak and insufficient to boost the efficiency of the solar cells. The objective of this article is to contribute to the study of this absorption by manufacturing and characterizing a QD IBSC with a single QD layer with and without light trapping elements. Using 1-D substrate texturing, our results show a three-fold increase in the absorption of below-bandgap energy photons in the lowest energy region of the spectrum, a region not previously explored using this approach. Furthermore, we also measure, at 9K, a distinguished split of quasi-Fermi levels between the conduction and intermediate bands, which is a necessary condition to preserve the output voltage of the cell.

ACS Style

Juan Villa; Inigo Ramiro; Jose Maria Ripalda; Ignacio Tobias; Pablo Garcia-Linares; Elisa Antolin; Antonio Marti. Contribution to the Study of Sub-Bandgap Photon Absorption in Quantum Dot InAs/AlGaAs Intermediate Band Solar Cells. IEEE Journal of Photovoltaics 2020, 11, 420 -428.

AMA Style

Juan Villa, Inigo Ramiro, Jose Maria Ripalda, Ignacio Tobias, Pablo Garcia-Linares, Elisa Antolin, Antonio Marti. Contribution to the Study of Sub-Bandgap Photon Absorption in Quantum Dot InAs/AlGaAs Intermediate Band Solar Cells. IEEE Journal of Photovoltaics. 2020; 11 (2):420-428.

Chicago/Turabian Style

Juan Villa; Inigo Ramiro; Jose Maria Ripalda; Ignacio Tobias; Pablo Garcia-Linares; Elisa Antolin; Antonio Marti. 2020. "Contribution to the Study of Sub-Bandgap Photon Absorption in Quantum Dot InAs/AlGaAs Intermediate Band Solar Cells." IEEE Journal of Photovoltaics 11, no. 2: 420-428.

Preprint content
Published: 09 December 2020
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We demonstrate a novel multijunction architecture, the heterojunction bipolar transistor solar cell (HBTSC), which exhibits the performance of a double-junction solar cell in a more compact npn (or pnp) semiconductor structure. The HBTSC concept has the advantages of being a three-terminal device, such as low spectral sensitivity and high tolerance to non-optimal band gap energies, while it reduces the fabrication and operation complexity with respect to other multi-terminal devices because, for example, it can produce independent power extraction from the two junctions without the need for extra layers for their isolation or inter-connection. The top and bottom junctions in our proof-of-concept HBTSC prototype, which is made of epitaxial GaInP/GaAs, exhibit independent current-voltage characteristics under AM1.5G illumination, with respective open-circuit voltages of 1.33 and 0.95 V. The voltage difference between the two junctions is notable considering that they share a thin (< 600 nm) GaInP layer which contributes to the photogeneration of both junctions. This can be explained by a gradient in the minority carrier quasi-Fermi level within the base layer, which is compatible with a high fill factor. We also offer a technological solution for contacting the intermediate layer and study the effect of series resistance on the device performance. The HBTSC opens a new perspective in the understanding of multi-junction devices and it is an excellent candidate for the application of low-cost fabrication techniques, and for the implementation of III-V on silicon tandems with parallel/series interconnection for high energy yield.

ACS Style

Marius Zehender; Simon Svatek; Myles Steiner; Ivan Garcia; Pablo Linares; Emily Warren; Adele Tamboli; Antonio Martí; Elisa Antolín. GaInP/GaAs three-terminal heterojunction bipolar transistor solar cell. 2020, 1 .

AMA Style

Marius Zehender, Simon Svatek, Myles Steiner, Ivan Garcia, Pablo Linares, Emily Warren, Adele Tamboli, Antonio Martí, Elisa Antolín. GaInP/GaAs three-terminal heterojunction bipolar transistor solar cell. . 2020; ():1.

Chicago/Turabian Style

Marius Zehender; Simon Svatek; Myles Steiner; Ivan Garcia; Pablo Linares; Emily Warren; Adele Tamboli; Antonio Martí; Elisa Antolín. 2020. "GaInP/GaAs three-terminal heterojunction bipolar transistor solar cell." , no. : 1.

Article
Published: 09 December 2020 in Physical Review Letters
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Intermediate band solar cells (IBSCs) promise high efficiencies while maintaining a low device structural complexity. A high efficiency can be obtained by harvesting below-band-gap photons, thus increasing the current, while at the same time preserving a high voltage. Here, we provide experimental proof that below-band-gap photons can be used to produce nonzero electrical work in an IBSC without compromising the voltage. For this, we manufacture a GaSb/GaAs quantum-dot IBSC. We use light biasing and make our cell operate at the maximum power point at 9 K. We measure the photocurrent response to absorption of photons with an energy of less than 1.15 eV while the cell is operating at 1.15 V. We also show that this result implies the existence of three quasi-Fermi levels linked to the three electronic bands in our device, as demanded by the IBSC theory to preserve the output voltage of the cell.

ACS Style

I. Ramiro; J. Villa; J. Hwang; A. J. Martin; J. Millunchick; J. Phillips; A. Martí. Demonstration of a GaSb/GaAs Quantum Dot Intermediate Band Solar Cell Operating at Maximum Power Point. Physical Review Letters 2020, 125, 247703 .

AMA Style

I. Ramiro, J. Villa, J. Hwang, A. J. Martin, J. Millunchick, J. Phillips, A. Martí. Demonstration of a GaSb/GaAs Quantum Dot Intermediate Band Solar Cell Operating at Maximum Power Point. Physical Review Letters. 2020; 125 (24):247703.

Chicago/Turabian Style

I. Ramiro; J. Villa; J. Hwang; A. J. Martin; J. Millunchick; J. Phillips; A. Martí. 2020. "Demonstration of a GaSb/GaAs Quantum Dot Intermediate Band Solar Cell Operating at Maximum Power Point." Physical Review Letters 125, no. 24: 247703.

Eu pvsec paper
Published: 21 October 2020 in Progress in Photovoltaics: Research and Applications
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In the quest for high‐efficiency photovoltaics (PV), the intermediate band solar cell (IBSC) was proposed in 1997 as an alternative to tandem solar cells. The IBSC offers 63% efficiency under maximum solar concentration using a single semiconductor material. This high‐efficiency limit attracted the attention of the PV community, yielding to numerous intermediate band (IB) studies and IBSC prototypes employing a plethora of candidate IB materials. As a consequence, the principles of operation of the IBSC have been demonstrated, and the particularities and difficulties inherent to each different technological implementation of the IBSC have been reasonably identified and understood. From a theoretical and experimental point of view, the IBSC research has reached a mature stage. Yet we feel that, driven by the large number of explored materials and technologies so far, there is some confusion about what route the IBSC research should take to transition from the proof of concept to high efficiency. In this work, we give our view on which the next steps should be. For this, first, we briefly review the theoretical framework of the IBSC, the achieved experimental milestones, and the different technological approaches used, with special emphasis on those recently proposed.

ACS Style

Iñigo Ramiro; Antonio Martí. Intermediate band solar cells: Present and future. Progress in Photovoltaics: Research and Applications 2020, 1 .

AMA Style

Iñigo Ramiro, Antonio Martí. Intermediate band solar cells: Present and future. Progress in Photovoltaics: Research and Applications. 2020; ():1.

Chicago/Turabian Style

Iñigo Ramiro; Antonio Martí. 2020. "Intermediate band solar cells: Present and future." Progress in Photovoltaics: Research and Applications , no. : 1.

Journal article
Published: 12 June 2020 in Energies
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Intermediate band solar cells (IBSCs) have an efficiency limit of 63.2%, which is significantly higher than the 40.7% limit for conventional single gap solar cells. In order to achieve the maximum efficiency, the total bandgap of the cell should be in the range of ~2 eV. However, that fact does not prevent other cells based on different semiconductor bandgaps from benefiting from the presence of an intermediate band (IB) within their bandgap. Since silicon (1.12 eV bandgap) is the dominant material in solar cell technology, it is of interest to determine the limit efficiency of a silicon IBSC, because even a modest gain in efficiency could trigger a large commercial interest if the IB is implemented at low cost. In this work we study the limit efficiency of silicon-based IBSCs considering operating conditions that include the use of non-ideal photon casting between the optical transitions, different light intensities and Auger recombination. The results lead to the conclusion that a silicon IBSC, operating under the conventional model in which the sub-bandgaps add to the total silicon gap, provides an efficiency gain if operated in the medium-high concentration range. The performance of these devices is affected by Auger recombination only under extremely high concentrations.

ACS Style

Esther López; Antonio Martí; Elisa Antolín; Antonio Luque. On the Potential of Silicon Intermediate Band Solar Cells. Energies 2020, 13, 1 .

AMA Style

Esther López, Antonio Martí, Elisa Antolín, Antonio Luque. On the Potential of Silicon Intermediate Band Solar Cells. Energies. 2020; 13 (12):1.

Chicago/Turabian Style

Esther López; Antonio Martí; Elisa Antolín; Antonio Luque. 2020. "On the Potential of Silicon Intermediate Band Solar Cells." Energies 13, no. 12: 1.

Journal article
Published: 18 March 2020 in Nanotechnology
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Mechanical manipulation of nanowires (NWs) for their integration in electronics is still problematic because of their reduced dimensions, risking to produce mechanical damage to the NW structure and electronic properties during the assembly process. In this regard, contactless NW manipulation based methods using non-uniform electric fields, like dielectrophoresis (DEP) are usually much softer than mechanical methods, offering a less destructive alternative for integrating nanostructures in electronic devices. Here, we report a feasible and reproducible dielectrophoretic method to assemble single GaAs NWs (with radius 35-50 nm, and lengths 3-5 μm) on conductive electrodes layout with assembly yields above 90% per site, and alignment yields of 95%. The electrical characteristics of the dielectrophoretic contact formed between a GaAs NW and conductive electrodes have been measured, observing Schottky barrier like contacts. Our results also show the fast fabrication of diodes with rectifying characteristics due to the formation of a low-resistance contact between the Ga catalytic droplet at the tip of the NW when using Al doped ZnO as electrode. The current-voltage characteristics of a single Ga-terminated GaAs NW measured in dark and under illumination exhibit a strong sensitivity to visible light under forward bias conditions (around two orders of magnitude), mainly produced by a change on the series resistance of the device.

ACS Style

Carlos García Núñez; Alejandro F Braña; Nair López; José L Pau; Basilio J García. Single GaAs nanowire based photodetector fabricated by dielectrophoresis. Nanotechnology 2020, 31, 225604 .

AMA Style

Carlos García Núñez, Alejandro F Braña, Nair López, José L Pau, Basilio J García. Single GaAs nanowire based photodetector fabricated by dielectrophoresis. Nanotechnology. 2020; 31 (22):225604.

Chicago/Turabian Style

Carlos García Núñez; Alejandro F Braña; Nair López; José L Pau; Basilio J García. 2020. "Single GaAs nanowire based photodetector fabricated by dielectrophoresis." Nanotechnology 31, no. 22: 225604.

Journal article
Published: 01 March 2020 in Energies
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In this work, we develop the general theory for analyzing the thermodynamic consistency of the Richardson–Duhmann model for vacuum thermionic energy converters. In addition to the electron fluxes from emitter to collector and vice versa, we calculate the energy and entropy fluxes associated to them. The calculation of the entropy fluxes is what allows us to conclude that the model is consistent by verifying that both at the emitter and at the collector the entropy generation rate is positive. In the process, we review the Richardson–Duhmann model in order to assure that the assumptions we make for calculating the energy and entropy fluxes are consistent. We also generalize the Richardson–Duhmann model in order to consider Fermi–Dirac statistics.

ACS Style

Antonio Martí. Analysis of the Thermodynamic Consistency of the Richardson–Duhmann Model for Thermionic Converters. Energies 2020, 13, 1087 .

AMA Style

Antonio Martí. Analysis of the Thermodynamic Consistency of the Richardson–Duhmann Model for Thermionic Converters. Energies. 2020; 13 (5):1087.

Chicago/Turabian Style

Antonio Martí. 2020. "Analysis of the Thermodynamic Consistency of the Richardson–Duhmann Model for Thermionic Converters." Energies 13, no. 5: 1087.

Journal article
Published: 23 October 2019 in IEEE Journal of Photovoltaics
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Independent current extraction in multijunction solar cells has gained attention in recent years because it can deliver higher annual energy yield and can work for more semiconductor material combinations than the more established series-connected multijunction technology. The heterojunction bipolar transistor solar cell concept (HBTSC) was recently proposed as a simple, compact, and cost-effective multiterminal device structure that allows independent current extraction. It consists of only three main layers: emitter, base, and collector. In this article, we use a drift-diffusion model to analyze important aspects in the design of an HBTSC structure based on typical III-V semiconductor materials. We find that carrier injection from the emitter into the collector (transistor effect) degrades the open-circuit voltage of the top sub-cell, but this risk can be eliminated by optimizing the base design. We find requirements for the base layer which are, in principle, achievable in the context of current III-V semiconductor technology.

ACS Style

Elisa Antolin; Marius H. Zehender; Pablo Garcia-Linares; Simon A. Svatek; Antonio Marti. Considerations for the Design of a Heterojunction Bipolar Transistor Solar Cell. IEEE Journal of Photovoltaics 2019, 10, 2 -7.

AMA Style

Elisa Antolin, Marius H. Zehender, Pablo Garcia-Linares, Simon A. Svatek, Antonio Marti. Considerations for the Design of a Heterojunction Bipolar Transistor Solar Cell. IEEE Journal of Photovoltaics. 2019; 10 (1):2-7.

Chicago/Turabian Style

Elisa Antolin; Marius H. Zehender; Pablo Garcia-Linares; Simon A. Svatek; Antonio Marti. 2019. "Considerations for the Design of a Heterojunction Bipolar Transistor Solar Cell." IEEE Journal of Photovoltaics 10, no. 1: 2-7.

Conference paper
Published: 01 September 2019 in 2019 European Space Power Conference (ESPC)
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Multi-terminal multi-junction solar cells (MJSC) offer higher efficiency potential than series connected (two-terminal) ones. In addition, for terrestrial applications, the efficiency of multi-terminal solar cells is less sensitive to solar spectral variations than the two-terminal series-connected one. In space, generally, cells are always illuminated with AM0 spectrum and no impact is expected from spectral variations. Still, in space, the multi-terminal approach offers some advantages in comparison with the series-connected architecture approach derived from a higher end of life (EOL) efficiency. In this work we review the potential of multi-terminal solar cells for achieving extended EOL efficiencies with emphasis in the potential of the three-terminal heterojunction bipolar transistor solar cell, a novel multi-terminal MJSC architecture with a simplified structure not requiring, for example, tunnel junctions.

ACS Style

Antonio Marti; Federica Cappelluti; Elisa Antolin; Pablo Garcia-Linares; Marius Zehender; Simon A. Svatek; Irene Artacho; Ana B. Cristobal; Jose R. Gonzalez; Carsten Baur; Inigo Ramiro. Potential of the three-terminal heterojunction bipolar transistor solar cell for space applications. 2019 European Space Power Conference (ESPC) 2019, 1 -5.

AMA Style

Antonio Marti, Federica Cappelluti, Elisa Antolin, Pablo Garcia-Linares, Marius Zehender, Simon A. Svatek, Irene Artacho, Ana B. Cristobal, Jose R. Gonzalez, Carsten Baur, Inigo Ramiro. Potential of the three-terminal heterojunction bipolar transistor solar cell for space applications. 2019 European Space Power Conference (ESPC). 2019; ():1-5.

Chicago/Turabian Style

Antonio Marti; Federica Cappelluti; Elisa Antolin; Pablo Garcia-Linares; Marius Zehender; Simon A. Svatek; Irene Artacho; Ana B. Cristobal; Jose R. Gonzalez; Carsten Baur; Inigo Ramiro. 2019. "Potential of the three-terminal heterojunction bipolar transistor solar cell for space applications." 2019 European Space Power Conference (ESPC) , no. : 1-5.

Journal article
Published: 20 August 2019 in IEEE Journal of Photovoltaics
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A heterojunction solar cell consists of a p-n junction between a high-bandgap and a low-bandgap semiconductor. As the cell is made up of two different semiconductors, the fundamental question that arises is whether the limiting efficiency of the heterojunction solar cell is determined by the low-bandgap semiconductor, the high-bandgap semiconductor, some value in-between or, perhaps, even some other value exceeding the limiting efficiency of single gap solar cells. In this respect, in this paper, we demonstrate that the limiting efficiency lies in-between, without the absolute limiting efficiency of single gap solar cells being exceeded. However, in spite of this result, we find that the open-circuit voltage of heterojunction solar cells can exceed the bandgap (divided by the electron charge) of the low-bandgap semiconductor, something that is not possible in single gap solar cells.

ACS Style

Antonio Marti. Limiting Efficiency of Heterojunction Solar Cells. IEEE Journal of Photovoltaics 2019, 9, 1590 -1595.

AMA Style

Antonio Marti. Limiting Efficiency of Heterojunction Solar Cells. IEEE Journal of Photovoltaics. 2019; 9 (6):1590-1595.

Chicago/Turabian Style

Antonio Marti. 2019. "Limiting Efficiency of Heterojunction Solar Cells." IEEE Journal of Photovoltaics 9, no. 6: 1590-1595.

Journal article
Published: 11 February 2019 in Solar Energy Materials and Solar Cells
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Practical device architectures are proposed here for the implementation of three-terminal heterojunction bipolar transistor solar cells (3T-HBTSCs). These photovoltaic devices, which have a potential efficiency similar to that of multijunction cells, exhibit reduced spectral sensitivity compared with monolithically and series-connected tandem solar cells. In addition, the simplified n-p-n (or p-n-p) structure does not require the use of tunnel junctions. In this framework, four architectures are proposed and discussed in this paper: 1) one in which the top cell is based on silicon and the bottom cell is based on a heterojunction between silicon and III-V nanomaterials; 2) one in which the top cell is made of amorphous silicon and the bottom cell is made of an amorphous silicon-silicon heterojunction; 3) one based on the use of III-V semiconductors aimed at space applications; and 4) one in which the top cell is based on a perovskite material and the bottom cell is made of a perovskite-silicon heterostructure.

ACS Style

Pablo G. Linares; Elisa Antolin; Antonio Marti. Novel heterojunction bipolar transistor architectures for the practical implementation of high-efficiency three-terminal solar cells. Solar Energy Materials and Solar Cells 2019, 194, 54 -61.

AMA Style

Pablo G. Linares, Elisa Antolin, Antonio Marti. Novel heterojunction bipolar transistor architectures for the practical implementation of high-efficiency three-terminal solar cells. Solar Energy Materials and Solar Cells. 2019; 194 ():54-61.

Chicago/Turabian Style

Pablo G. Linares; Elisa Antolin; Antonio Marti. 2019. "Novel heterojunction bipolar transistor architectures for the practical implementation of high-efficiency three-terminal solar cells." Solar Energy Materials and Solar Cells 194, no. : 54-61.

Conference paper
Published: 08 November 2018 in AIP Conference Proceedings
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A new kind of systems combining latent heat energy storage in molten silicon and thermophotovoltaic (TPV) heat-to-power conversion are under development within the AMADEUS (www.amadeus-project.eu) project. The extremely high latent heat of silicon (1230 kWh/m3) plus the very high electrical power density of TPV (several 10’s of kW/m2) will eventually enable the fabrication of ultra-compact CSP systems that integrate thermal energy storage and power generation in the same unit. This work deals with the search of the optimal geometry of the PCM vessel, enabling the highest energy transfer to the TPV converter. Two kinds of geometries are explored: the inverted truncated pyramid (ITP) and the hollow cylinder (HC). A simplified quasi-1D semi-analytical model for the heat transfer in the PCM coupled to a TPV optical cavity model is used to simulate the system and determine some key figures of performance such as discharge efficiency, discharge time or electrical power. On top of that, the assumptions made in the 1-D model are verified against a well advanced 3-D Computational Fluid Dynamics (CFD) model, which takes into account buoyancy effects, dendrites formation and the PCM expansion during solidification, being thus in position to describe in more detail the induced complicated fluid structures governing both the phenomena of PCM melting and solidification. We find that both the analytical model and the advanced 3D CFD model coincide for most of the simulation time, enhancing the validity of the analytical model that can be implemented during the initial stages of the system design. Finally, the article discusses on the best geometries resulting in the maximum system efficiency and output power, as a result from the 1D analysis.

ACS Style

Alejandro Datas; Myrto Zeneli; Carlos Del Cañizo; Ilias Malgarinos; Aristeidis Nikolopoulos; Nikolaos Nikolopoulos; Sotirios Karellas; Antonio Martí. Molten silicon storage of concentrated solar power with integrated thermophotovoltaic energy conversion. AIP Conference Proceedings 2018, 2033, 090005 .

AMA Style

Alejandro Datas, Myrto Zeneli, Carlos Del Cañizo, Ilias Malgarinos, Aristeidis Nikolopoulos, Nikolaos Nikolopoulos, Sotirios Karellas, Antonio Martí. Molten silicon storage of concentrated solar power with integrated thermophotovoltaic energy conversion. AIP Conference Proceedings. 2018; 2033 (1):090005.

Chicago/Turabian Style

Alejandro Datas; Myrto Zeneli; Carlos Del Cañizo; Ilias Malgarinos; Aristeidis Nikolopoulos; Nikolaos Nikolopoulos; Sotirios Karellas; Antonio Martí. 2018. "Molten silicon storage of concentrated solar power with integrated thermophotovoltaic energy conversion." AIP Conference Proceedings 2033, no. 1: 090005.

Conference paper
Published: 01 November 2018 in 2018 Spanish Conference on Electron Devices (CDE)
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Thermophotovoltaic (TPV) devices produce the direct conversion of radiant heat into electricity using infrared sensitive photovoltaic (PV) cells. Despite its relatively mature stage of development a standardized method for the measurement of the TPV conversion efficiency hasn't been established yet, which represents a serious issue for the TPV research development. In this work we present results on a novel method to directly measure the conversion efficiency of a TPV device. This method relies on the direct measurement of the electrical power and the heat dissipated by the TPV cell in the steady state. In this article, we present preliminary results on the efficiency of a TPV device illuminated by a halogen lamp at different incident irradiances and vacuum conditions.

ACS Style

A. Cabrera; A. Ramos; I. Artacho; M. Gomez; K. Gavin; Antonio Marti; Alejandro Datas. Thermophotovoltaic Efficiency Measurement: Design and Analysis of a Novel Experimental Method. 2018 Spanish Conference on Electron Devices (CDE) 2018, 1 -4.

AMA Style

A. Cabrera, A. Ramos, I. Artacho, M. Gomez, K. Gavin, Antonio Marti, Alejandro Datas. Thermophotovoltaic Efficiency Measurement: Design and Analysis of a Novel Experimental Method. 2018 Spanish Conference on Electron Devices (CDE). 2018; ():1-4.

Chicago/Turabian Style

A. Cabrera; A. Ramos; I. Artacho; M. Gomez; K. Gavin; Antonio Marti; Alejandro Datas. 2018. "Thermophotovoltaic Efficiency Measurement: Design and Analysis of a Novel Experimental Method." 2018 Spanish Conference on Electron Devices (CDE) , no. : 1-4.

Conference paper
Published: 13 September 2018 in AIP Conference Proceedings
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In common multijunction solar cells the subcells are connected in series. In this way, achieving a high voltage at module level is straightforward. However, calculations have proven that the annual energy efficiency limit is higher for independently connected subcells, because they are more tolerant to spectral variations throughout the year. We have recently proposed a three-terminal heterojunction bipolar transistor solar cell (HBTSC) with the maximum limiting efficiency of a dual-junction solar cell, but without the need for a tunnel junction and with only three crucial semiconductor layers. In this work, we present the implementation of a two-terminal module prototype including five HBTSCs which provides a high-voltage power output.

ACS Style

Marius H. Zehender; Elisa Antolin; Pablo García-Linares; Irene Artacho; Iñigo Ramiro; Juan Villa; Antonio Martí. Module interconnection for the three-terminal heterojunction bipolar transistor solar cell. AIP Conference Proceedings 2018, 2012, 040013 .

AMA Style

Marius H. Zehender, Elisa Antolin, Pablo García-Linares, Irene Artacho, Iñigo Ramiro, Juan Villa, Antonio Martí. Module interconnection for the three-terminal heterojunction bipolar transistor solar cell. AIP Conference Proceedings. 2018; 2012 (1):040013.

Chicago/Turabian Style

Marius H. Zehender; Elisa Antolin; Pablo García-Linares; Irene Artacho; Iñigo Ramiro; Juan Villa; Antonio Martí. 2018. "Module interconnection for the three-terminal heterojunction bipolar transistor solar cell." AIP Conference Proceedings 2012, no. 1: 040013.

Conference paper
Published: 01 January 2018
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ACS Style

Alejandro Datas; Ana Belén. Cristobal; Carlos Del Cañizo; Elisa Antolin; Michel Beaughon; Nikolaos Nikolopoulos; Aristeidis Nikolopoulos; Myrto Zeneli; Natalia Sobczak; Wojciech Polkowski; Merete Tangstad; Jafar Safarian; Daniele Maria Trucchi; Alessandro Bellucci; Marco Girolami; Roman Marx; Dominik Bestenlehner; Stephan Lang; Aniello Vitulano; Gianfranco Sabbatella; Antonio Martí. AMADEUS: Next generation materials and solid state devices for ultra high temperature energy storage and conversion. 2018, 1 .

AMA Style

Alejandro Datas, Ana Belén. Cristobal, Carlos Del Cañizo, Elisa Antolin, Michel Beaughon, Nikolaos Nikolopoulos, Aristeidis Nikolopoulos, Myrto Zeneli, Natalia Sobczak, Wojciech Polkowski, Merete Tangstad, Jafar Safarian, Daniele Maria Trucchi, Alessandro Bellucci, Marco Girolami, Roman Marx, Dominik Bestenlehner, Stephan Lang, Aniello Vitulano, Gianfranco Sabbatella, Antonio Martí. AMADEUS: Next generation materials and solid state devices for ultra high temperature energy storage and conversion. . 2018; ():1.

Chicago/Turabian Style

Alejandro Datas; Ana Belén. Cristobal; Carlos Del Cañizo; Elisa Antolin; Michel Beaughon; Nikolaos Nikolopoulos; Aristeidis Nikolopoulos; Myrto Zeneli; Natalia Sobczak; Wojciech Polkowski; Merete Tangstad; Jafar Safarian; Daniele Maria Trucchi; Alessandro Bellucci; Marco Girolami; Roman Marx; Dominik Bestenlehner; Stephan Lang; Aniello Vitulano; Gianfranco Sabbatella; Antonio Martí. 2018. "AMADEUS: Next generation materials and solid state devices for ultra high temperature energy storage and conversion." , no. : 1.

Article
Published: 15 September 2017 in Physical Review B
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Quantum-dot (QD) intermediate-band (IB) materials are regarded as promising candidates for high-efficiency photovoltaics. The sequential two-step two-photon absorption processes that take place in these materials have been proposed to develop high-efficiency solar cells and infrared (IR) photodetectors. In this work, we experimentally and theoretically study the interrelation of the absorptivity with transitions of carriers to and from the IB in type-II GaSb/GaAs QD devices. Our devices exhibit three optical band gaps with: EL=0.49eV,EH=1.02eV, and EG=1.52eV, with the IB located 0.49 eV above the valence band. These values are well supported by semiempirical calculations of the QDs electronic structure. Through intensity-dependent two-photon photocurrent experiments, we are able to vary the filling state of the IB, thus modifying the absorptivity of the transitions to and from this band. By filling the IB with holes via E=1.32eV or E=1.93eV monochromatic illumination, we demonstrate an increase in the EL-related absorptivity of more than two orders of magnitude and a decrease in the EH-related absorptivity of one order of magnitude. The antisymmetrical evolution of those absorptivities is quantitatively explained by a photoinduced shift of the quasi-Fermi level of the IB. Furthermore, we report the observation of a two-photon photovoltage, i.e., the contribution of subband gap two-photon absorption to increase the open-circuit voltage of solar cells. We find that the generation of the two-photon photovoltage is related, in general, to the production of a two-photon photocurrent. However, while photons with energy close to EL participate in the production of the two-photon photocurrent, they are not effective in the production of a two-photon photovoltage. We also report the responsivity of GaSb/GaAs QD devices performing as optically triggered photodetectors. These devices exhibit an amplification factor of almost 400 in the IR spectral region. This high value is achieved by minimizing—via doping—the absorptivity in the IR range of the QDs under equilibrium conditions.

ACS Style

I. Ramiro; J. Villa; C. Tablero; Elisa Antolin; A. Luque; Antonio Marti; J. Hwang; Jamie Phillips; A. J. Martin; J. Millunchick. Analysis of the intermediate-band absorption properties of type-II GaSb/GaAs quantum-dot photovoltaics. Physical Review B 2017, 96, 125422 .

AMA Style

I. Ramiro, J. Villa, C. Tablero, Elisa Antolin, A. Luque, Antonio Marti, J. Hwang, Jamie Phillips, A. J. Martin, J. Millunchick. Analysis of the intermediate-band absorption properties of type-II GaSb/GaAs quantum-dot photovoltaics. Physical Review B. 2017; 96 (12):125422.

Chicago/Turabian Style

I. Ramiro; J. Villa; C. Tablero; Elisa Antolin; A. Luque; Antonio Marti; J. Hwang; Jamie Phillips; A. J. Martin; J. Millunchick. 2017. "Analysis of the intermediate-band absorption properties of type-II GaSb/GaAs quantum-dot photovoltaics." Physical Review B 96, no. 12: 125422.

Journal article
Published: 01 September 2017 in Solar Energy Materials and Solar Cells
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ACS Style

Mohammadreza Nematollahi; Esther López; Iñigo Ramiro; Pablo G. Linares; Elisa Antolin; Irene Artacho; César Tablero; Eric Karhu; Turid W. Reenaas; Antonio Marti. Interpretation of photovoltaic performance of n -ZnO:Al/ZnS:Cr/p-GaP solar cell. Solar Energy Materials and Solar Cells 2017, 169, 56 -60.

AMA Style

Mohammadreza Nematollahi, Esther López, Iñigo Ramiro, Pablo G. Linares, Elisa Antolin, Irene Artacho, César Tablero, Eric Karhu, Turid W. Reenaas, Antonio Marti. Interpretation of photovoltaic performance of n -ZnO:Al/ZnS:Cr/p-GaP solar cell. Solar Energy Materials and Solar Cells. 2017; 169 ():56-60.

Chicago/Turabian Style

Mohammadreza Nematollahi; Esther López; Iñigo Ramiro; Pablo G. Linares; Elisa Antolin; Irene Artacho; César Tablero; Eric Karhu; Turid W. Reenaas; Antonio Marti. 2017. "Interpretation of photovoltaic performance of n -ZnO:Al/ZnS:Cr/p-GaP solar cell." Solar Energy Materials and Solar Cells 169, no. : 56-60.

Journal article
Published: 29 June 2017 in IEEE Journal of Photovoltaics
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In this work, we study the limiting efficiency of the annual energy production of multijunction solar cells both as independently connected (MJSC-IC) and as series connected (MJSC-SC). Our calculations take into account the impact of hourly and daily variations of the solar spectrum and the geographical latitude. The results confirm the lower dependence with the solar spectrum of independently connected MJSCs and suggest that, in order to progress in practice toward higher annual energy production efficiencies, it could be advisable to develop a 5-junction MJSC-IC rather than to increase the number of solar cells from 5 to 6 under the MJSC-SC approach.

ACS Style

Juan Villa; Antonio Marti. Impact of the Spectrum in the Annual Energy Production of Multijunction Solar Cells. IEEE Journal of Photovoltaics 2017, 7, 1479 -1484.

AMA Style

Juan Villa, Antonio Marti. Impact of the Spectrum in the Annual Energy Production of Multijunction Solar Cells. IEEE Journal of Photovoltaics. 2017; 7 (5):1479-1484.

Chicago/Turabian Style

Juan Villa; Antonio Marti. 2017. "Impact of the Spectrum in the Annual Energy Production of Multijunction Solar Cells." IEEE Journal of Photovoltaics 7, no. 5: 1479-1484.

Conference paper
Published: 01 June 2017 in 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC)
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Removed.

ACS Style

Inigo Ramiro; Elisa Antolin; Jinyoung Hwang; Alan Teran; Andrew J. Martin; Joanna Millunchick; Jamie Phillips; Antonio Marti; Antonio Luque. Notice of Removal Three-bandgap absolute quantum efficiency in intermediate band solar cells. 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC) 2017, 1 -3.

AMA Style

Inigo Ramiro, Elisa Antolin, Jinyoung Hwang, Alan Teran, Andrew J. Martin, Joanna Millunchick, Jamie Phillips, Antonio Marti, Antonio Luque. Notice of Removal Three-bandgap absolute quantum efficiency in intermediate band solar cells. 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC). 2017; ():1-3.

Chicago/Turabian Style

Inigo Ramiro; Elisa Antolin; Jinyoung Hwang; Alan Teran; Andrew J. Martin; Joanna Millunchick; Jamie Phillips; Antonio Marti; Antonio Luque. 2017. "Notice of Removal Three-bandgap absolute quantum efficiency in intermediate band solar cells." 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC) , no. : 1-3.