Welding Perovskite Nanowires for Stable, Sensitive, Flexible Photodetectors.

Compared with single Nanowire (NW) or NW array, the simpler preparation process of NW network (NWN) enables it to be fabricated in large scale, flexible, and wearable applications of photodetectors (PDs). However, the NWN behaves many micro-interfaces (MIs) between NWs, seriously limiting the device performance and stability. Here, we demonstrate a welding strategy for MAPbI3 NWN, which enhances the crystallinity of NWN, and enhances the radial transmission of photogenerated carriers, leading to the better device performance with ultrahigh stability. Our NWN PDs fabricated by using the welding strategy showed ultrahigh performance with the on/off ratio and detectivity of 2.8×104 and 4.16×1012 Jones, respectively, which are the best performance for the 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 ultra-high storage stability in air with 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, and no performance degradation can be observed. These results indicate our welding strategy is very powerful for improving the performance of NW device with application in wearable field.