III–V-on-silicon solar cells reaching 33% photoconversion efficiency in two-terminal configuration

• Published in: Nature energy Vol. 3; no. 4; pp. 326 - 333
• Main Authors: Cariou, Romain, Benick, Jan, Feldmann, Frank, Höhn, Oliver, Hauser, Hubert, Beutel, Paul, Razek, Nasser, Wimplinger, Markus, Bläsi, Benedikt, Lackner, David, Hermle, Martin, Siefer, Gerald, Glunz, Stefan W., Bett, Andreas W., Dimroth, Frank
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01.04.2018
• Subjects: Efficiency; Electric power; Energy conversion efficiency; Engineering Sciences; Gallium arsenide; Gallium indium phosphide; Gratings (spectra); Group III-V semiconductors; Photovoltaic cells; Photovoltaics; Quantum efficiency; Silicon; Solar cells
• ISSN: 2058-7546; 2058-7546
• DOI: 10.1038/s41560-018-0125-0

Silicon dominates the photovoltaic industry but the conversion efficiency of silicon single-junction solar cells is intrinsically constrained to 29.4%, and practically limited to around 27%. It is possible to overcome this limit by combining silicon with high-bandgap materials, such as III–V semiconductors, in a multi-junction device. Significant challenges associated with this material combination have hindered the development of highly efficient III–V/Si solar cells. Here, we demonstrate a III–V/Si cell reaching similar performances to standard III–V/Ge triple-junction 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's weak absorption are addressed using poly-silicon/SiOx passivating contacts and a novel rear-side diffraction grating for the silicon bottom cell. With these combined features, we demonstrate a two-terminal GaInP/GaAs//Si solar cell reaching a 1-sun AM1.5G conversion efficiency of 33.3%.