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Six-junction IIIa??V solar cells with 47.1% conversion efficiency under 143a??Suns concentration
摘要： Single-junction flat-plate terrestrial solar cells are fundamentally limited to about 30% solar-to-electricity conversion efficiency, but multiple junctions and concentrated light make much higher efficiencies practically achievable. Until now, four-junction III–V concentrator solar cells have demonstrated the highest solar conversion efficiencies. Here, we demonstrate 47.1% solar conversion efficiency using a monolithic, series-connected, six-junction inverted metamorphic structure operated under the direct spectrum at 143 Suns concentration. When tuned to the global spectrum, a variation of this structure achieves a 1-Sun global efficiency of 39.2%. Nearly optimal bandgaps for six junctions were fabricated using alloys of III–V semiconductors. To develop these junctions, it was necessary to minimize threading dislocations in lattice-mismatched III–V alloys, prevent phase segregation in metastable quaternary III–V alloys and understand dopant diffusion in complex structures. Further reduction of the series resistance within this structure could realistically enable efficiencies over 50%.
关键词： III–V solar cells,multijunction solar cells,concentrator solar cells,solar conversion efficiency
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - A computationally efficient simulation method for optimizing front contacts of concentrator multijunction solar cells
摘要： In this work, a novel multidiode model is proposed for optimizing the front grid of multijunction solar cells operating under concentration conditions. The model allows for quickly exploring the maximum achievable efficiency under a wide range of operating conditions and design parameters such as the redirecting capability, period and width of the fingers, the light concentration, and the metal and emitter sheet resistivity. The proposed multidiode model shows to be consistent with experimental data and with more complex modeling approaches such as the simulation program with integrated circuit emphasis (SPICE) model.
关键词： multijunction solar cells,concentrator photovoltaics,device modeling,solar cell front contact grids
更新于2025-09-19 17:13:59
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Development and Analysis of Wafer-Bonded Four-Junction Solar Cells Based on Antimonides With 42% Efficiency Under Concentration
摘要： The highest solar cell efficiencies today are reached with four-junction devices under concentrated illumination. The optimal bandgap combination for realistic four-junction cells is modelled to be 1.89/1.42/1.05/0.68 eV and indeed promises for efficiencies >50%. We present the development and analysis of a wafer-bonded four-junction solar cell based on GaInP/GaAs/GaInAs//GaInAsSb. This concept allows for the implementation of these ideal bandgaps and exhibits at present an efficiency of 42.0±2.5% at a concentration of 599x AM1.5d. The present loss mechanisms in this device are analyzed, which are dominated by current losses due to mismatched subcell currents and absorbing passive layers. Under the assumption of proper current matching, this device would achieve an efficiency above 44%.
关键词： metal-organic vapour phase epitaxy (MOVPE),multijunction solar cells,wafer bonding,Antimonides,four-junction solar cells
更新于2025-09-16 10:30:52
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The Influence of Solar Spectrum and Concentration Factor on the Material Choice and the Efficiency of Multijunction Solar Cells
摘要： In this work, we revisit the theoretical study on the conversion efficiency of series-connected multijunction solar cells. The theoretical method, based on the detailed balance model, is then applied to devices with 2 to 6 junctions under different illumination conditions. As results, (i) we show that the peaks in the efficiency distribution occur for recurrent values of bottom junction bandgap energy corresponding to atmospheric absorption in the solar spectrum, and (ii) we demonstrate that variations in the number of junctions, in the incident solar spectrum, and in the concentration factor lead to changes in the optimum bandgap energy set but that the bottom junction bandgap energy only changes among the recurrent values presented before. Additionally, we highlight that high conversion efficiencies take place for a broad distribution of bandgap energy combination, which make the choice of materials for the device more flexible. Therefore, based on the overall results, we propose more than a hundred III-V, II-VI and IV semiconductor material candidates to compose the bottom junction of highly efficient devices.
关键词： conversion efficiency,material choice,concentration factor,Multijunction solar cells,solar spectrum
更新于2025-09-16 10:30:52
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[IEEE 2019 34th Symposium on Microelectronics Technology and Devices (SBMicro) - Sao Paulo, Brazil (2019.8.26-2019.8.30)] 2019 34th Symposium on Microelectronics Technology and Devices (SBMicro) - Study on the Influence of the Luminescence Coupling in Dual Junction Solar Cells
摘要： The multijunction solar cell concept has proven to be a very efficient way of converting solar into electrical energy. Theoretical calculations using the detailed balance model aim in the optimization process of finding the best materials (in terms of bandgap energies) to compose the device junctions. However, along with other simplifications, such model applied to multijunction solar cells fails in considering one important physical effect: the luminescence coupling amongst the junctions. In this work, we present a method based on a self-consistent numerical approach for implementing the luminescence coupling in the detailed balance model applied to multijunction solar cells. We show results on the influence of the effect on the performance of different dual junction solar cells in which a coupling factor and the junction bandgap energies are varied. Therefore, we show that the main impact of the luminescence coupling is in the raise of the solar cell short circuit current, and consequently, their conversion efficiencies. Moreover, we highlight that the influence of the effect is more important for the bandgap energy combinations that would lead to low efficiencies. This is an important result towards the choice of materials by allowing more combinations to achieve high efficiencies.
关键词： Luminescence Coupling,Detailed Balanced Model,Theoretical Calculation,Multijunction Solar Cells
更新于2025-09-12 10:27:22
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III‐V//Si multijunction solar cells with 30% efficiency using smart stack technology with Pd nanoparticle array
摘要： Multijunction (MJ) solar cells achieve very high efficiencies by effectively utilizing the entire solar spectrum. Previously, we constructed a III‐V//Si MJ solar cell using the smart stack technology, a unique mechanical stacking technology with Pd nanoparticle array. In this study, we fabricated an InGaP/AlGaAs//Si three‐junction solar cell with an efficiency of 30.8% under AM 1.5G solar spectrum illumination. This efficiency is considerably higher than our previous result (25.1%). The superior performance was achieved by optimizing the structure of the upper GaAs‐based cell and employing a tunnel oxide passivated contact Si cell. Furthermore, we examined the low solar concentration performance of the device and obtained a maximum efficiency of 32.6% at 5.5 suns. This performance is sufficient for realistic low concentration photovoltaic applications (below 10 suns). In addition, we characterize the reliability of the InGaP/AlGaAs//Si three‐junction solar cell with a damp heat test (85 °C and 85% humidity for 1000 h). It was confirmed that our solar cells have high long‐term stability under severe conditions. The results demonstrate the potential of GaAs//Si MJ solar cells as next‐generation photovoltaic cells and the effectiveness of smart stack technology in fabricating multijunction cells.
关键词： III‐V solar cells,photovoltaic concentrator,mechanical stack,multijunction solar cells,silicon solar cells
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Toward a simple and accurate spectral balance monitoring of solar simulators for multijunction solar cells
摘要： Currently, solar simulators demand component solar cells, also named isotypes, in order to equilibrate their spectrum and match the required norm. Each architecture of cell needs a specific set of isotypes and each one of them need calibration in order to assess the incident power coming from the solar simulator in its spectral range. In this article, pseudo-isotypes are proposed in order to ease the spectral balance of new architectures of multijunction solar cells (MJSC). Pseudo-isotypes are silicon and germanium photodiodes filtered with filters reproducing the cut-on and the cut-off of each MJSC subcell. The use of pseudo-isotypes requires the development of a simple and accurate calibration in order to obtain the constants associated with these references without sending it to a certified laboratory. An indoor calibration method is described and its accuracy is assessed. IV characteristics of 3J MJSC under a solar simulator are carried out with different sets of references: i) isotypes calibrated outdoor, ii) isotypes calibrated indoor, and iii) pseudo-isotypes calibrated indoor.
关键词： indoor calibration,solar simulators,multijunction solar cells,pseudo-isotypes,spectral balance
更新于2025-09-11 14:15:04