Compared with a single nanowire (NW) or NW array, the simpler preparation process of an NW network (NWN) enables it to be fabricated in large-scale, flexible, and wearable applications of photodetectors (PDs). However, the NWN behaves many microinterfaces (MIs) between NWs, seriously limiting the device performance and stability. Here, we demonstrate a welding strategy for an MAPbI3 NWN, which enhances the crystallinity of the NWN and enhances the radial transmission of photogenerated carriers, leading to a better device performance with ultrahigh stability. Our NWN PDs fabricated by using the welding strategy showed ultrahigh performance with an on/off ratio and detectivity of 2.8 × 104 and 4.16 × 1012 Jones, respectively, which are the best performance for reported metal–semiconductor–metal (MSM) perovskite NWN PDs and are comparable to those of single-NW or NW array PDs. More importantly, our unpackaged NWN PDs show ultrahigh storage stability in air with a humidity of 55–65%, and the flexible NWN PDs can enable 250 bending cycles at different bending radii and 1000 bending cycles at fixed bending radii with no performance degradation being observed. These results indicate our welding strategy is very powerful for improving the performance of the NW device with applications in the wearable field.

Photodetectors (PDs) based on perovskite nanowires are among the most promising next‐generation photodetection technologies; however, their poor long‐term stability is the biggest challenge limiting their commercial application. Herein, an ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4), is incorporated as an additive into methylammonium lead triiodide (MAPbI3) nanowires; this not only effectively passivates defects to inhibit perovskite degradation but also leads to the formation of nanochannels, enabling fast charge transfer. As a result, the long‐term stability and performance of MAPbI3 nanowires are considerably improved. The detectivity, linear detection range, and noise equivalent power of the MAPbI3 nanowire PD reach 2.06 × 1013 Jones, 160 dB, and 1.38 × 10−15 W Hz−1/2, respectively, comparable to the highest performance of perovskite nanowire PDs reported to date. Moreover, the unencapsulated PD can maintain 100% of its initial performance after being exposed to an open‐air environment for more than 5000 h, establishing it as the most stable perovskite nanowire PD reported to date. Notably, the PD exhibits improved diffuse reflection imaging ability when compared with commercial silicon photodiode S2386. This study provides a new strategy for constructing sensitive, stable, and flexible perovskite PDs and will accelerate their commercial application in the future.

The carrier transport layer with reflection reduction morphology has attracted extensive attention for improving the utilization of light. Herein, we introduced single-layer hollow ZnO hemisphere arrays (ZHAs) behaving light trapping effect as the electron transport layer in perovskite photodetectors (PDs). The single-layer hollow ZHAs can not only reduce the reflection, but also widen the angle of the effective incident light and especially transfer the distribution of the optical field from the ZnO/FTO interface to the perovskite active layer confirmed by the 3D finite-difference time-domain simulation. These merits benefit for the generation, transport and separation of carriers, improving the light utilization efficiency. Finally, our optimized FTO/ZHA/CsPbBr3/carbon structure PDs showed high self-powered performance with a linear dynamic range of 120.3 dB, a detectivity of 4.2 × 1012 Jones, rise/fall time of 13/28 µs and the f−3 dB of up to 28 kHz. Benefiting from the high device performance, the PD was demonstrated to the application in the directional transmission of encrypted files as the signal receiving port with super high accuracy. This work uniquely utilizes the features of high-performance self-powered perovskite PDs in optical communication, paving the path to wide applications of all-inorganic perovskite PDs.

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devices in VLC are essential because their response speed, detectivity (D*), and stability determine the quality and speed of the signal acceptance. All-inorganic perovskites are very attractive for their application in the PDs with requirements of high durability, wide-range spectral responses, ultra-high D*, and fast response speed, due to their merits of high thermal stability, tunable bandgaps, high light absorption coefficients, and long carrier diffusion lengths. [2][3][4][5] Particularly, cesium lead bromide (CsPbBr 3 ), a prototypical all-inorganic perovskite with a bandgap energy of 2.4 eV, has been widely used for fabricating solar cells and PDs. [6] The preparation of high-quality CsPbBr 3 films with a large lateral area is crucial for their commercialization. Luchkin et al. fabricated inorganic CsPbBr 3 perovskite solar cells with the best efficiency of 3.9% by using a vacuum deposition process. The poor efficiency was attributed to the off-stoichiometric ratios of the vacuum-processed precursors. [7] Recently, inorganic perovskite quantum dots (QDs) were developed to fabricate perovskite photoelectronic devices, demonstrating decent device performance. [8,9] However, these perovskite films consisted of mosaic QDs capped with a large amount of organic ligands and surface traps, which hinder the carrier transport and limit the device performance. Solutionprocessed CsPbBr 3 polycrystalline (PC) films are an attractive alternative due to better process controllability, endowing them with great potential for large-scale commercial fabrication of perovskite photoelectronic devices. [10][11][12][13] Unfortunately, the fabrication of high-quality CsPbBr 3 PC films via solution processes is challenging. The low solubility of CsBr in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) solvents causes insufficient and unbalanced reaction of the precursors, which leads to discontinuous and porous morphology and off-stoichiometric compositions in solution-processed perovskite films. [14,15] Additionally, due to the much lower solubility of CsBr than that of PbBr 2 in the solvents, CsBr behaves as the growth seeds during the nucleation of perovskite crystallites, which aggravates the formation of voids and impurity phases, hindering the achievement of the high-performance PDs. [16] Cesium lead bromide (CsPbBr 3 ) perovskite photodetectors (PDs) are attractive for applications in visible light communication (VLC) due to ultra-high detectivity and fast response speed. However, the fabrication of high-quality CsPbBr 3 polycrystalline films using solution-based process is very challenging. Due to the low solubility of CsBr in precursor solutions, solution-processed CsPbBr 3 films are typically discontinuous and porous, hindering the performance of resulting PDs. Herein, a facile and modified sequential spin-coating method is introduced to prepare high-crystallinity, pinhole-free CsPb 2 Br 5 -CsPbBr 3 perovskite films with an average grain size of ≈1 µm. The hole-transport-layer-free (HTL-free) PDs based on the CsPb ...