Halide Ordering Enables Superior Charge Transport in 3D (NMPDA)Pb 2 I 4 Br 2 Perovskitoid Single Crystal.

Halide composition engineering has been demonstrated as an effective strategy for optical and electronic properties modulation in 3D perovskites. While the impact of halide mixing on the structural and charge transport properties of 3D perovskitoids remains largely unexplored. Herein, it is demonstrated that bromine (Br) mixing in 3D (NMPDA)Pb 2 I 6 (NMPDA = N-methyl-1,3-propane diammonium) perovskitoid yields stabilized (NMPDA)Pb 2 I 4 Br 2 with specific ordered halide sites, where Br ions locate at the edge-sharing sites. The halide ordered structure enables stronger H-bonds, shorter interlayer distance, and lower octahedra distortion in (NMPDA)Pb 2 I 4 Br 2 with respect to the pristine (NMPDA)Pb 2 I 6 . These attributes further result in high ion migration activation energy, low defect states density, and enhanced carrier mobility-lifetime product (µτ), as underpinned by the electrical properties investigation and DFT calculations. Remarkably, the parallel configured photodetector based on (NMPDA)Pb 2 I 4 Br 2 single crystal delivers a high on/off current ratio of 3.92 × 10 3 , a satisfying photoresponsivity and detectivity of 0.28 A W -1 and 3.05 × 10 12 Jones under 10.94 µW cm -2 irradiation, superior to that of (NMPDA)Pb 2 I 6 and the reported 3D perovskitoids. This work sheds novel insight on exploring 3D mixed halide perovskitoids toward advanced and stable optoelectronic devices.