The Influence of Operation Temperature and Variations of the Illumination on the Performance of Integrated Photoelectrochemical Water-Splitting Devices

Renewable and storable fuel hydrogen can be produced through light-driven water splitting using photovoltaic-biased electrosynthetic (PV-EC) devices. The required voltage to drive the reaction is approximately 1.5 V, which can be provided using multi-junction silicon solar cells. To generate these voltages at the operation point, the solar cells are electrically optimized with respect to the standard test conditions. However, if such devices were to be used outdoors, a wide range of different illumination conditions has to be considered. Herein, we discuss the dependence of the solar-to-hydrogen efficiency on the spectral quality, the incident illumination intensity and the operation temperature. It is found that in the case of high irradiation intensities (e.g. 1 sun), high operation temperatures reduce the PV performance, but the overall PV-EC device performance remains almost unchanged due to improved kinetics in the EC part. In contrast, when the illumination intensity is reduced, the loss in PV performance cannot be compensated by improved EC performances due to higher temperatures.