Solution-Processed Monolithic All-Perovskite Triple-Junction Solar Cells with Efficiency Exceeding 20%

Very high power conversion efficiencies (PCEs) have been demonstrated by multijunction cells made of epitaxial III–V semiconductors; but they are too expensive to manufacture for terrestrial applications. Multijunction solar cells that can be fabricated with cheap and simple solution-processing techniques offer a lower-cost alternative to reach high PCEs. Here we demonstrate the solution processing of efficient all-perovskite triple-junction solar cells using optimal-bandgap perovskites. Monolithic all-perovskite triple-junction cells with an open-circuit voltage of 2.8 V and a fill factor of 81.1% are obtained by developing interconnecting layers that are compatible with the solution processing of perovskite absorbers. The concept and design here represent an important step toward efficient all-perovskite triple-junction solar cells.