All-Perovskite Tandem Solar Cells: From Certified 25% and Beyond

Perovskite-based solar cells are a promising photovoltaic technology capable of offering higher conversion efficiency at low costs compared with the standard of the market. They can be produced via a thin film technology that allows for considerable environmental sustainability, thus representing an efficient, sustainable, flexible, and light solution. Tandem solar cells represent the next step in the evolution of photovoltaics (PV). They promise higher power conversion efficiency (PCE) than those currently dominating the market. The tandem solar cell design overcomes the limitations of single junction solar cells by reducing the thermal losses as well as the manufacturing costs. Perovskite has been employed as a partner in different kinds of tandem solar cells, such as the Si and CIGS (copper indium gallium selenide) based cells that, in their tandem configuration with perovskite, can convert light more efficiently than standalone sub-cells. This brief review presents the main engineering and scientific challenges in the field. The state-of-the-art three main perovskite tandem technologies, namely perovskite/silicon, perovskite/CIGS, and perovskite/perovskite tandem solar cells, will be discussed, providing a side-by-side comparison of theoretical and experimental efficiencies of multijunction solar cells.