A three-dimensional lead iodide-bromide perovskitoid with distinct photoelectric anisotropy†

Abstract

Three-dimensional (3D) hybrid perovskitoids have shown immense potential in optoelectronic applications. However, it is still challenging to achieve photoelectric anisotropy in 3D perovskitoids. Herein, we report a 3D (NMPDA)Pb₂I₄Br₂ (NMPDA = N-methyl propane diammonium) perovskitoid with strong anisotropic merits, achieved by the incorporation of Br⁻ ions. The preferential distribution of Br⁻ ions at the edge-sharing halide sites triggers distinct structural anisotropy, balanced distortion and microstrain relaxation. The structural anisotropy yields a highly anisotropic band structure, which enables remarkable charge transport anisotropy, with the [001] direction enabling higher carrier mobility and longer carrier diffusion length than the [010] direction. Consequently, the 3D (NMPDA)Pb₂I₄Br₂ single crystal manifests a responsivity and detectivity of 0.40 A W⁻¹ and 4.85 × 10¹² Jones, respectively, along the preferred [001] direction, which are orders of magnitude larger compared to the [010] direction, and outperforms the reported 3D perovskitoids. Moreover, the (NMPDA)Pb₂I₄Br₂ single crystal device shows a sensitive response to polarized light, involving a responsivity and detectivity of 1.07 A W⁻¹ and 7.05 × 10¹² Jones, respectively. These observations offer novel insights into the development of 3D perovskitoids toward advanced optoelectronic devices.