Wavelength selective and cesium halides additive photodetectors based on two-dimensional perovskite: (C₈H₉NH₃)₂PbBr₄

Considering of cost-effective and simple assembly principle of organic-inorganic halide perovskite (OIHP), producing perovskites into polycrystalline thin films from precursor solution has proved to be appealing. In this paper, (C₈H₉NH₃)₂PbBr₄ was fabricated based on C₈H₉NH₃Br (PEABr) and PbBr₂ according to compositions in the vicinity of (PEA)₂PbI₄, and the two-dimensionally (2D) perovskite was obtained which entitled with superior photoelectric performance, excellent solution processability and flexible substrates compatibility. And hydrophobic nature of spacer cation of aromatic alkylammonium or a large aliphatic both with the highly consistent orientation of 2D perovskites are beneficial for reducing the grain boundaries density. Meanwhile, optimized (PEA)₂PbBr₄ were obtained via CsBr additive. Systematic material characterizations manifested enhanced surface morphology, photoluminescence efficiency and carrier lifetime of the CsBr modified (PEA)₂PbBr₄. Then related (PEA)₂PbBr₄ based photodetectors exhibited a good responsivity of 0.67 AW⁻¹ when detectivity approached 5.2×10¹¹ Jones, and a large on/off ratio about 500 was obtained. Meanwhile, the devices possessed noticeable stability during the optical switch tests with the rise time and decay time about 0.28 s and 0.21 s for CsBr dopped devices illuminated by 385 nm under 10 V bias. More importantly, spectral wavelength selectivity of CsBr based photodetector indicated the potential utilization in ultraviolet detecting when a wide bandgap of 3.018 eV was obtained.