Engineered Surface Halide Defects by Two-Dimensional Perovskite Passivation for Deformable Intelligent Photodetectors

Abstract

As attractive photoactive materials, metal halide perovskites demonstrate outstanding performance in a wide range of optoelectronic applications. Among the various compositions studied, mixed-halide perovskites have a finely tunable band gap that renders them desirable for targeted applications. Despite their advantages, photoinduced halide segregation often deters the photoelectric stability of the materials. Herein, we adopt a strategy of post-treating the perovskite surface with an organic spacer to generate a two-dimensional (2D) perovskite passivating layer. Trap-assisted recombination pathways can be selectively modulated by passivating the surface halide defects that cause photoinduced halide segregation. Fluorescence lifetime imaging of flat and bent surfaces of perovskites reveals that the perovskite lattice tolerates mechanical strain via the neutralizing passivation of ionic halide defects. Upon bending, the photocurrent response of the flexible photodetector is maintained over 83% for 2D passivated perovskite and drops to 23% for pristine perovskite. A flexible photodetector array built with 2D passivated perovskite, in combination with a deep learning algorithm, demonstrates excellent accuracy in determining letters of the alphabet for both flat (>96%) and bent (>93%) states. The connection of chemically modified charge carrier dynamics and mechanical properties revealed in this study offers valuable guidance for developing next-generation optoelectronic applications.

Lanthanide ion doping enabling highly sensitive and stable all-inorganic CsPbI2Br perovskite photodetectors

“…The t rise and t drop before and after doping reduce from 729 ns, 1.3 μs to 640 ns, 870 ns, which is close to the two-dimensional perovskite photodetector. 34,35 Fig. S12 and S13 (ESI†) further reveal that the performance of the detector after doping is better than that of undoped device under different optical power densities.…”

Metal‐Free PAZE‐NH4X3⋅H2O Perovskite for Flexible Transparent X‐ray Detection and Imaging

“…Notably, the contrast between flexible and rigid images is not clear enough, which may be ascribed to the appearance of the signal/electrical crosstalk in the 3×3 pixelated X‐ray imager. The contrast can be further optimized by reducing pixel size (<10 μm) and a deep learning algorithm [41, 59] . Therefore, these different results adequately indicate the advantage of flexible devices in non‐flat objects and narrow space imaging [7] …”

“…The contrast can be further optimized by reducing pixel size (< 10 μm) and a deep learning algorithm. [41,59] Therefore, these different results adequately indicate the advantage of flexible devices in non-flat objects and narrow space imaging. [7] Meanwhile, the single-pixel imaging ability is also conducted by fitting the target object on a moving XÀ Y stage, and recording the different photocurrents of the detector.…”

Fluorination and Conjugation Engineering Synergistically Enhance the Optoelectronic Properties of Two-Dimensional Hybrid Organic–Inorganic Perovskites

“…Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) have attracted extensive research interest due to their exotic physical properties and wide range of applications, including solar cells (SCs), light-emitting diodes, photodetectors, and laser, with the advantages of enhanced environmental stability, structural flexibility, and tunable chemical composition and properties. − In particular, the power conversion efficiency (PCE) of SCs based on 2D HOIPs ( n ≤ 10) has increased from 4.73 to 21.07% in the past 8 years. , However, the strong dielectric confinement effect caused by the alternating arrangement of the bulky organic cations and inorganic layers in 2D HOIPs leads to low carrier mobility, large exciton binding energy and bandgap, and inappropriate energy band alignment, limiting the PCE improvement of 2D HOIP-based SCs to lag behind their three-dimensional (3D) counterparts. − …”