Welding Perovskite Nanowires for Stable, Sensitive, Flexible Photodetectors

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.