Photovoltaics based on nanowire arrays could reduce cost and materials consumption compared with planar devices but have exhibited low efficiency of light absorption and carrier collection. We fabricated a variety of millimeter-sized arrays of p-type/intrinsic/n-type (p-i-n) doped InP nanowires and found that the nanowire diameter and the length of the top n-segment were critical for cell performance. Efficiencies up to 13.8% (comparable to the record planar InP cell) were achieved by using resonant light trapping in 180-nanometer-diameter nanowires that only covered 12% of the surface. The share of sunlight converted into photocurrent (71%) was six times the limit in a simple ray optics description. Furthermore, the highest open-circuit voltage of 0.906 volt exceeds that of its planar counterpart, despite about 30 times higher surface-to-volume ratio of the nanowire cell.
A metamorphic Ga0.35In0.65P/Ga0.83In0.17As/Ge triple-junction solar cell is shown to provide current-matching of all three subcells and thus composes a device structure with virtually ideal band gap combination. We demonstrate that the key for the realization of this device is the improvement of material quality of the lattice-mismatched layers as well as the development of a highly relaxed Ga1-yInyAs buffer structure between the Ge substrate and the middle cell. This allows the metamorphic growth with low dislocation densities below 10(6) cm(-2). The performance of the approach has been demonstrated by a conversion efficiency of 41.1% at 454 suns (454 kW/m(2), AM1.5d ASTM G173-03)
Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2022 are reviewed. Graphs showing progress with each cell technology over the 30‐year history of the tables are also included plus an updated list of designated test centres.
Triple-junction solar cells from III-V compound semiconductors have thus far delivered the highest solar-electric conversion efficiencies. Increasing the number of junctions generally offers the potential to reach even higher efficiencies, but material quality and the choice of bandgap energies turn out to be even more importance than the number of junctions. Several four-junction solar cell architectures with optimum bandgap combination are found for lattice-mismatched III-V semiconductors as high bandgap materials predominantly possess smaller lattice constant than low bandgap materials. Direct wafer bonding offers a new opportunity to combine such mismatched materials through a permanent, electrically conductive and optically transparent interface. In this work, a GaAs-based top tandem solar cell structure was bonded to an InP-based bottom tandem cell with a difference in lattice constant of 3.7%. The result is a GaInP/GaAs//GaInAsP/GaInAs four-junction solar cell with a new record efficiency of 44.7% at 297-times concentration of the AM1.5d (ASTM G173-03) spectrum. This work demonstrates a successful pathway for reaching highest conversion efficiencies with III-V multi-junction solar cells having four and in the future even more junctions.
Silicon is the predominant semiconductor in photovoltaics. However, the conversion efficiency of silicon single junction solar cells is intrinsically constrained to 29.4%, and practically limited around 27%. It is nonetheless possible to overcome this limit by combining silicon with high bandgap materials, such as III-V semiconductors, in a multi-junction device. Despite numerous studies tackling III-V/Si integration, the significant challenges associated with this material combination has hindered the development of highly efficient III-V/Si solar cells. Here we demonstrate for the first time a III-V/Si cell reaching similar performances than standard III-V/Ge triple-junctions solar cells. This device is fabricated using wafer bonding to permanently join a GaInP/GaAs top cell with a silicon bottom cell.The key issues of III-V/Si interface recombination and silicon weak absorption are addressed using polysilicon/SiOx passivating contacts and a novel rear side diffraction grating for the silicon bottom cell. With these combined features, we demonstrate a 2-terminal GaInP/GaAs//Si solar cell reaching a 1sun AM1.5g conversion efficiency of 33.3%.
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