Vapor-Tailored Nanojunctions in Ultraporous ZnO Nanoparticle Networks for Superior UV Photodetection.

High quality nanojunctions are known to effectively improve the conductivity and structural robustness of ultraporous nanoparticle networks, surpassing the performance of natural van der Waals interfaces. Nevertheless, the traditional approach of forming these junctions by thermal annealing is incompatible with thermolabile polymers and slender metal electrodes found in modern wearable technologies. Herein, we present a low temperature, solvent vapor-based method to rapidly elicit high-quality metal-oxide nanojunctions in a fast, effortless, inexpensive, and easily scalable process; capable of generating necked interparticle interfaces in a matter of minutes. When applied to ultraporous-based ZnO Ultraviolet (UV) photodetectors, the vapor-tailoring process produces an incredible 128,000-fold improvement in responsivity (6.6 A.W) over untreated structures (51.2 µA.W), and a 5300-fold improvement in responsivity over thermally annealed structures; all while maintaining exceptionally low dark currents of 140 pA at a low bias voltage of 1 V. Most importantly, the exceptional performance enabled by room temperature synthesis suggests high potential adaptability of this process toward wearable UV sensors, shedding lights on the strategy of modifying weakly bonded porous nanostructures for improved physical properties.