A polar two-dimensional lead-free hybrid perovskite for self-powered polarization-sensitive photodetection†
Abstract
Two-dimensional (2D) lead hybrid perovskites have attracted great attention due to their excellent stability and unique physical and chemical properties. Nevertheless, the toxicity of lead remains an urgent issue. Lead-free homovalent substituents (Sn2+and Ge2+) suffer from poor oxygen-sensitive stability, posing a serious challenge to their device applications. Compared to homovalent substituents, heterovalent substituted perovskites based on the VA group elements, especially bismuth, exhibit excellent stability, making them more competitive. However, 2D Bi-based perovskites with the composition 2D A2BiX4 (A = organic cation; X = Cl−, Br− or I−) cannot be formed considering the charge balance. Here, by reducing the occupancy rate of Bi3+ ions, we successfully obtained the first polar 2D Bi-based perovskite (4BrPEA)3BiI6 (4BrPEA = 4-bromophenethylammonium) with an A2PbX4-like layered structure. (4BrPEA)3BiI6 exhibits a narrow bandgap (2.00 eV) and excellent photoelectric response performance. Specifically, a single crystal device based on (4BrPEA)3BiI6 has been explored for self-powered polarization-sensitive photodetection with a large photocurrent anisotropic ratio ω of 2.16. This work demonstrates the great potential of heterovalent substituted 2D lead-free perovskites and opens up a new way to expand the synthesis of environmentally friendly and high-performance self-powered polar optoelectronic semiconductor materials.
- This article is part of the themed collections: 2024 Inorganic Chemistry Frontiers HOT articles and FOCUS: Recent progress on bioimaging technologies