Perovskite Tandems: the Next Big Leap in Photovoltaic Technology.

The global demand for clean energy is driving the need for next-generation solar technologies with higher power conversion efficiencies. Multijunction solar cells, which stack absorbers with cascaded bandgaps, offer a compelling path forward by more efficiently utilizing the solar spectrum. Among these, metal halide perovskites stand out for their bandgap tunability, enabling efficient tandem solar cells (TSCs) when paired with a range of semiconductors-including perovskite/perovskite, perovskite/silicon, perovskite/organic, and perovskite/CIGS. Central to these architectures are wide-bandgap perovskites, which harvest high-energy, short-wavelength photons. This review highlights recent advances and challenges in perovskite-based TSCs, focusing on the photophysical properties and application of wide-bandgap perovskites across different tandem configurations. Future research directions are outlined aimed at enhancing performance and long-term stability to accelerate industrial deployment.