Localized Lattice Expansion of FAPbBr3 to Design a 3D Hybrid Perovskite for Sensitive Near-Infrared Photodetection

A mixed-cation 3D lead bromide hybrid perovskite (NMDAP)(2)FAPb(4)Br(13) (1, NMDAP(2+) = N-methyl-1,3-diaminopropanium, FA(+) = formamidinium) is tailored by incorporating the large NMDAP(2+) cation with the small FA(+) ion into 3D FAPbBr(3). Structurally, the small FA(+) ions occupy the prototypical cavities formed by distorted corner-sharing PbBr6 octahedra as in FAPbBr(3), while the bulky NMDAP(2+) ions are confined to the expanded lattice which is defined by a new structural motif composed of eight corner-sharing PbBr6 octahedra and four edge-sharing octahedra. This localized lattice expansion from FAPbBr(3) creates a new branch of the intriguing 3D hybrid perovskite family, breaking the limits of the conventional Goldschmidt tolerance factor rule. Moreover, a high two-photon absorption (2AP) coefficient of 60.8 cm MW-1 was demonstrated to near-infrared (NIR) 800 nm illumination, enabling sensitive NIR photoresponses with large on/off ratio (approximate to 10(4)) as well as favorable stability.

Automated summary

A new mixed-cation 3D lead bromide hybrid perovskite material was tailored by incorporating NMDAP(2+) and FA(+) ions into FAPbBr(3). The material exhibits localized lattice expansion and high two-photon absorption coefficient, making it promising for applications in NIR photoresponses and stability.