Translator Disclaimer
5 June 2018 Photonic structures for III-V//Si multi-junction solar cells with efficiency >33%
Author Affiliations +
Silicon based multi-junction solar cells are a promising option to overcome the theoretical efficiency limit of a silicon solar cell (29.4%). With III-V semiconductors, high bandgap materials applicable for top cells are available. For the application of such silicon based multi-junction devices, a full integration of all solar cell layers in one 2-terminal device is of great advantage. We realized a triple-junction device by wafer-bonding two III-V-based top cells onto the silicon bottom cell. However, in such a series connected solar cell system, the currents of all sub-cells need to be matched in order to achieve highest efficiencies. To fulfil the current matching condition and maximise the power output, photonic structures were investigated. The reference system without photonic structures, a triple-junction cell with identical GaInP/GaAs top cells, suffered from a current limitation by the weakly absorbing indirect semiconductor silicon bottom cell. Therefore rear side diffraction gratings manufactured by nanoimprint lithography were implemented to trap the infrared light and boost the solar cell current by more than 1 mA/cm2. Since planar passivated surfaces with an additional photonic structure (i.e. electrically planar but optically structured) were used, the optical gain could be realized without deterioration of the electrical cell properties, leading to a strong efficiency increase of 1.9% absolute. With this technology, an efficiency of 33.3% could be achieved.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Benedikt Bläsi, Oliver Höhn, Hubert Hauser, Nico Tucher, Romain Cariou, Jan Benick, Frank Feldmann, Paul Beutel, David Lackner, Gerald Siefer, Stefan W. Glunz, Andreas W. Bett, Frank Dimroth, and Martin Hermle "Photonic structures for III-V//Si multi-junction solar cells with efficiency >33%", Proc. SPIE 10688, Photonics for Solar Energy Systems VII, 1068803 (5 June 2018);

Back to Top