Review on two-terminal and four-terminal crystalline-silicon/perovskite tandem solar cells; progress, challenges, and future perspectives

Silicon (Si) solar cells are the dominant and well-developed solar technology holding more than 95% share of the photovoltaic market with efficiencies over 26%. Still, this value is far away from the Shockley–Queisser limit of 33.15% for single-junction devices. A prominent way to surpass this limit and boost the device performance is to combine different bandgap materials in a tandem configuration. The rapid emergence of perovskite solar cells (PSCs) as one of the most exciting research fields with over 25% efficiency has attracted the focus of the scientific community. The solution-processability, bandgap tunability, and outstanding optoelectronic properties of perovskites mark them a potential pair with silicon to develop tandem solar cells (TSCs). In nearly seven to eight years of development, Si/perovskite TSCs have achieved record certified efficiencies of over 29%. This review emphasizes on two and four-terminal Si/perovskite TSCs. Initially, the advancement of efficiencies to date is discussed, including a comparison of numerous perovskite and silicon material choices. Then, the evolution of PSCs with Si (homojunction and heterojunction) bottom devices and their impact on the performance of TSCs is summarized. The suitable candidates for the perovskite and Si cells are proposed for Si/perovskite TSCs. Next, factors influencing the performance of tandems, such as fabrication issues on textured surfaces, parasitic absorption, reflection losses, nonideal perovskite absorber layer bandgap, device instability, and large-area fabrication, are highlighted. To reduce the electrical and optical losses for highly efficient tandems, an investigation of anti-reflecting coatings, current matching mechanisms, transparent electrodes, and recombination layers is discussed. Finally, based on these findings, future guidelines are proposed to boost the efficiencies beyond 30%. To the best of our knowledge, this is the first detailed study on two and four-terminal Si/perovskite TSCs. These findings would open new avenues for the research community with detailed information on Si/perovskite tandem cells.