Crystalline silicon solar cells with thin poly-SiOx carrier-selective passivating contacts for perovskite/c-Si tandem applications

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.

Automated summary

In this study, c-Si bottom cells based on high temperature poly-SiOx CSPCs were developed, and high efficiency four-terminal and two-terminal perovskite/c-Si tandem solar cells were demonstrated. By tuning the ultra-thin, thermally grown SiOx and optimizing the electrical properties of both n-type and p-type doped poly-SiOx CSPCs, conversion efficiencies of 28.1% and 23.2% were achieved in 4T and 2T tandems, respectively.