Thermally integrated photoelectrochemical devices with perovskite/silicon tandem solar cells: a modular approach for scalable direct water splitting

Direct solar water splitting appears as a promising route to produce hydrogen avoiding competition for electricity against other important economic uses. Halogenated hybrid perovskites recently enabled the demonstration of efficient and potentially low-cost photoelectrochemical cells and PV-coupled electrolysers, reaching high efficiencies but so far limited to small active area of a few mm2 so far, in the case of perovskite/silicon tandem solar cells. Here, we show the added value of integrating a thermal exchanger into the system thanks to additive manufacturing, providing a thermally integrated photoelectrochemical cell (IPEC) with performance doubled against the device without any heat exchanger (from 3.3 to 8 % STH). In addition, we develop a modular approach to up-scale this concept from 7.6 to 342 cm², highlighting statistical variations in efficiency of single integrated photoelectrochemical cells and their origin. We conduct an outdoor stability test for 72 hours, with a STH performance of 6.3 %, and investigate the causes of device degradation through the easy disassembly of the integrated photoelectrochemical devices. We identify the interface between perovskite layer and p-layer as critical for reaching stable photoelectrochemical devices integrating perovskite/silicon tandem solar cells.