(Invited) Confined and Free-Standing Perovskite Nanowires for X-Ray Detection

Abstract

Metal halide perovskites (MHPs) have shown excellent results in many applications, including X-ray scintillation detection. Nanowires could offer improved sensitivity by exploiting nanophotonic light guiding, and the MHP stability could be improved by growing nanowires physically protected in anodized aluminum oxide (AAO). We use a one-step solution low-temperature method to grow arrays of long single-crystalline CsPbBr3 nanowires in an AAO template. The diameters can be adjusted by the AAO template, ranging from 30 to 360 nm, and the length can be controlled up to 15 μm (Fig 1(a)) [1]. The nanowires show excellent stability, with no obvious lack in photoluminescence after months of storage in air. The X-ray scintillation shows no systematic degradation over 2 weeks of continuous X-ray exposure, but an unexpected positive correlation with room humidity. The excellent stability allows tomographic 3D X-ray imaging at better than 3 μm resolution [2].Surprisingly, we find that free-standing CsPbBr3 nanowires can be obtained by the same method (Fig 1(b)) [3]. The length of the vertically aligned nanowires is controlled from 1 to 20 μm with the precursor amount. The nanowires are single-crystalline and exhibit excellent photoluminescence and clear light guiding (Fig 1(c)). Lithography methods for MHPs have been limited because of their solubility in polar solvents. However, we show that o-xylene can be used in a perovskite-compatible electron beam lithography (EBL) process based on nonpolar solvents [4]. Combining these results, we demonstrate single nanowire devices with excellent photoresponse. Recently, we have developed a gas-phase halide exchange method based on HCl or Cl2 to convert the green-emitting CsPbBr3 to blue-emitting CsPb(BrxCl1-x)3. [5]. Using the aforementioned EBL process, we selectively convert segments of nanowires to CsPb(BrxCl1-x)3 and create axially heterostructured nanowires (Fig 1(d)).1 Z. Zhang, H. Dierks, N. Lamers et al., "Single-Crystalline Perovskite Nanowire Arrays for Stable X-ray Scintillators with Micrometer Spatial Resolution" ACS Applied Nano Materials 5 (1), 881 (2022) http://doi.org/10.1021/acsanm.1c035752 H. Dierks, Z. Zhang, N. Lamers, and J. Wallentin, "3D X-ray microscopy with a CsPbBr3 nanowire scintillator" Nano Res. 16 (1), 1084 (2023) https://doi.org/10.1007/s12274-022-4633-73 Z. Zhang, N. Lamers, C. Sun, C. Hetherington, I. G. Scheblykin, and J. Wallentin, "Free-Standing Metal Halide Perovskite Nanowire Arrays with Blue-Green Heterostructures" Nano Lett. 22 (7), 2941 (2022) http://doi.org/10.1021/acs.nanolett.2c001374 N. Lamers, Z. Zhang, and J. Wallentin, "Perovskite-Compatible Electron-Beam-Lithography Process Based on Nonpolar Solvents for Single-Nanowire Devices" ACS Applied Nano Materials 5 (3), 3177 (2022) http://doi.org/10.1021/acsanm.2c001885 N. Lamers, Z. Zhang, I. G. Scheblykin, and J. Wallentin, "Multisegment Heterostructured CsPb(Br1-xClx)3 Perovskite Nanowires using Gas-Phase Anion Exchange" In review (2023) Figure 1