Record-high solar-to-hydrogen conversion efficiency based on a monolithic all-silicon triple-junction IBC solar cell

• Published in: Solar energy materials and solar cells 2019-03, Vol.191, p.422-426
• Main Authors: Nordmann, S., Berghoff, B., Hessel, A., Zielinsk, B., John, J., Starschich, S., Knoch, J.
• Format: Article
• Language: English
• Subjects: Circuits; Electrodes; Electrolysis; Energy conversion efficiency; IBC silicon solar cells; Multi-junction solar cells; Open circuit voltage; Photoelectric conversion; Photoelectrochemical cells; Photovoltaic cells; Platinum; Redox potential; Ruthenium; Short circuit currents; Short-circuit current; Silicon; Solar cells; Sulfuric acid
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2018.11.004

We present a record-high solar-to-hydrogen conversion efficiency (STH) for monolithic all-silicon multi-junction solar devices. The device is based on an interdigitated back-contact silicon solar cell, in which the p- and n-regions are connected in a combination of series and parallel contacts, in order to triple the photovoltage compared to a single-junction cell. Our best device provides an open-circuit voltage of 1.99 V, larger than the water redox potential of 1.23 V plus overpotentials at the electrodes, as well as a short-circuit current density of 12.6 mA/cm2. Coupled to a sulphuric acid electrolysis system, with platinum and ruthenium dioxide electrodes, our device shows an STH of 14.5% at 1.63 V. •Record high solar-to-hydrogen conversion efficiency of 14.5% for all-Si solar cells.•Concept based on a monolithic triple-junction IBC solar cell.•Open-circuit voltage: 1.99 V, short-circuit current: 12.6 mA/cm2.•A solar-to-hydrogen conversion efficiency of 15.7% is possible.