The Second Spacer Cation Assisted Growth of a 2D Perovskite Film with Oriented Large Grain for Highly Efficient and Stable Solar Cells.

The fabrication of high-quality film with large grains oriented along the direction of film thickness is important for 2D Ruddlesden-Popper perovskite-based solar cells (PVSCs). High-quality 2D BA MA Pb I (BA =butylammonium, MA =methylammonium, n=5) perovskite films were fabricated with a grain size of over 1 μm and preferential orientation growth by introducing a second spacer cation (SSC ) into the precursor solution. Dynamic light scattering showed that SSC addition can induce aggregation in the precursor solution.