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Single junction crystalline silicon (c-Si) solar cells are reaching their practical efficiency limit whereas perovskite/c-Si tandem solar cells have achieved efficiencies above the theoretical limit of single junction c-Si solar cells. Next to low-thermal budget silicon heterojunction architecture, high-thermal budget carrier-selective passivating contacts (CSPCs) based on polycrystalline-SiOx (poly-SiOx) also constitute a promising architecture for high efficiency perovskite/c-Si tandem solar cells. In this work, we present the development of c-Si bottom cells based on high temperature poly-SiOx CSPCs and demonstrate novel high efficiency four-terminal (4T) and two-terminal (2T) perovskite/c-Si tandem solar cells. First, we tuned the ultra-thin, thermally grown SiOx. Then we optimized the passivation properties of p-type and n-type doped poly-SiOx CSPCs. Here, we have optimized the p-type doped poly-SiOx CSPC on textured interfaces via a two-step annealing process. Finally, we integrated such bottom solar cells in both 4T and 2T tandems, achieving 28.1% and 23.2% conversion efficiency, respectively.

How can we integrate photovoltaic (PV) solar energy systems in the built environment and rural landscapes while increasing societal support and making effective use of space? This important research question is inspired by several grand societal challenges, namely humankind’s response to anthropogenic causes of climate change, the required sustainable energy transition and innovations in the design of systems, products, buildings and local infrastructures which enable an optimal use of solar energy. Consequently, new sustainable energy environments must be created which will meet the needs of users, will fit in a societal context, will have an excellent performance in energy production and which will be aesthetically appealing. For this purpose a new interdisciplinary Dutch research consortium has been established, which will evaluate so-called ‘Solar Integration’ from the perspectives of (1) public acceptance, law and governance, (2) biodiversity, ecosystems and spatial quality, (3) PV system configurations in rural and urban landscapes, (4) enabling technologies for integrated PV elements, and (5) design approaches. This research consortium will support Solar Integration by (a) design-driven research on innovations in PV solar energy, (b) the creation of a broad consortium of stakeholders with various backgrounds and interests, (c) execution of the project in both the Netherlands and internationally, and (d) involving adult and young citizens in knowledge utilization.