High performance printable perovskite solar cells based on Cs0.1FA0.9PbI3 in mesoporous scaffolds

Abstract Methylammonium lead triiodide (MAPbI 3 ) has been investigated as the recent most exciting light absorber materials for photovoltaics. Printable perovskite solar cells based on MAPbI 3 in a TiO 2 /ZrO 2 /Carbon triple-layer mesoporous scaffold have shown simple fabrication process and impressive stability. Moving towards formamidinium lead triiodide (FAPbI 3 ) as the light absorber, which has a bandgap of 1.48 eV that matches the optimum bandgap (1.34 eV) of a single-junction solar cell, will result in further improvement in power conversion efficiency. However, it is challenging to deposit high-quality FAPbI 3 in a 10-μm-thick mesoporous scaffold due to the incomplete one-step conversion of perovskite precursors restrained in the mesoporous scaffold. Here we report printable perovskite solar cells with high-quality Cs 0.1 FA 0.9 PbI 3 absorber inside mesoporous scaffolds using a mixed solvent vapor assisted crystallization approach. A power conversion efficiency of 15% is obtained with a spectral response up to 840 nm. The phase transition and crystal growth of Cs 0.1 FAPbI 3 are carefully monitored in the mesoporous scaffold. This work not only opens up new methods for fabricating efficient and stable solar cells but also provides a deeper understanding of crystal growth inside constrained nanostructures.