Mobile Media Promotes Orientation of 2D/3D Hybrid Lead Halide Perovskite for Efficient Solar Cells

2D/3D hybrid perovskites have shown great environmental stability for use as solar cells. Yet insulating organic cation spacers affect the formation of vertically oriented crystalline grains to hamper carrier transport. To date, the selection of cation spacers is limited because crystal growth kinetics should be strictly obeyed. Here, we adopted a mobile-media-assisted method to fabricate highly oriented 2D/3D hybrid perovskite films, wherein bulky molecules of (C(CH 3 ) 3 NH 3, TBA) are used as cation spacers. We found the compositional volatile salt promote the orientation of perovskite polycrystalline films with various compositions universally. And we obtained efficient solar cells with a photoelectric conversion efficiency (PCE) of 17.38% and a certified PCE of 19.30% based on 2D/3D hybrid perovskites an overall stoichiometry matching n = 10 and 20, respectively, which are one of the highest efficiencies among all 2D/3D hybrid perovskite based solar cells so far. These findings largely broaden the selection category of bulky cations and promote further exploration of more functional organic cations.