The aqueous instability of halide perovskite seriously hinders its direct application in water as a potential photocatalyst. Here, we prepared a new type of polyvinylpyrrolidone (PVP) passivated δ-CsPbI3(δ-CsPbI3@PVP) microcrystal by a facile method. This material can be uniformly dispersed in water and stably maintain its crystal structure for a long time, breaking through the bottleneck of halide perovskite photocatalysis in water. Under visible light, δ-CsPbI3@PVP can almost completely photodegrade organic dyes (including Rhodamine B, methylene blue, and crystal violet) in only 20 min. The efficient photocatalytic activity is attributed to the enhanced visible light absorption arising from PbI2defects in δ-CsPbI3@PVP and the intrinsic low photoluminescence quantum yield of δ-CsPbI3, which induces efficient light absorption and photocatalytic activity. We highlight δ-CsPbI3@PVP as an effective aqueous photocatalyst, and this study provides new insights into how to exploit the potential of halide perovskite in photocatalytic applications.
The development of efficient room-temperature broadband emitters based on self-trapped excitons in low-dimensional perovskites has been hindered by severe thermal quenching, which stems from insufficient thermal activation energy (Ea) and poorly optimized electron–phonon interactions. Here, we introduce a bromine-alloyed strategy in quasi-one-dimensional δ-CsPbI3 to enhance the self-trapped luminescence efficiency. Structural analysis reveals that Br incorporation selectively tunes the distortion of the PbX6 octahedra. This targeted lattice distortion acts as a unified design parameter: it concurrently deepens the potential wells for self-trapped excitons, thereby increasing Ea by more than an order of magnitude (from 7.4 to 117.2 meV) to suppress thermal quenching, while also optimally moderating the electron–phonon coupling strength (Huang–Rhys factor, S). Systematic compositional optimization shows that CsPb(I0.35Br0.65)3 achieves the optimal balance, with a large Ea (82.9 meV) for stability and a moderated S (∼40) for efficient radiative recombination. This work elucidates the structural origin for the synergistic tuning of photophysical parameters, providing quantitative design principles for tailoring efficient self-trapped emission in low-dimensional perovskites and advances their prospects for solid-state lighting and photonic applications.
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.
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