Highly Anisotropic Quasi-1D δ-CsPbI3 Single Nanowire Decorated with Au Nanoparticles for Polarization-Sensitive Photodetection

The development of polarization-sensitive photodetectors based on low-dimensional materials with intrinsic lattice anisotropy has paved the way for next-generation polarizer-free and integration-friendly polarization-sensitive optoelectronic devices. Despite their superiority in miniaturization, the relatively low dichroic ratios (DRs) hinder further industrialization. In this work, low-dimensional derivatives of perovskite, quasi-1D yellow-phase (δ-phase) CsPbI 3 single nanowires (NWs) are investigated for polarization-sensitive photodetection. Aberration-corrected transmission electron microscopy (TEM) and angle-resolved polarized Raman spectroscopy (ARPRS) reveal the pronounced crystallographic anisotropy of δ-CsPbI 3 . The pristine δ-CsPbI 3 single NW photodetector exhibits a large DR of up to 8.3 under 405 nm illumination. To overcome the limited optoelectronic performance arising from the indirect bandgap nature of δ-CsPbI 3 , localized surface plasmon resonance (LSPR) is introduced by decorating the δ-CsPbI 3 single NW with Au nanoparticles (NPs) via thermal evaporation. The Au-decorated device exhibits up to approximately 9-fold photocurrent enhancement compared with the pristine one, achieving a photoresponsivity ( R ) of 5.3 mA W –1 and a specific detectivity ( D *) of 1.1 × 10 10 Jones while retaining the high polarization sensitivity. In addition, the Au-decorated device demonstrates appreciable operational stability under ambient conditions, preserving 92% of its initial photocurrent after 400 switching cycles. This work unveils the great potential of the δ-CsPbI 3 single NW for polarized light detection and demonstrates the feasibility of Au NP decoration regarding optoelectronic performance optimization, which can potentially be extended to other low-dimensional perovskite derivatives with analogous quasi-1D chain lattices.