Solution-processed novel core-shell n-p heterojunction and its ultrafast UV photodetection properties

We demonstrate the feasibility of fabricating a solution-processed novel core-shell coaxial n-p nanorod (NR) heterojunction consisting of an n-type ZnO NR core and a p-type CuS shell through an ion-exchange route. The field emission scanning electron and high resolution transmission electron microscopy experiments show evidence of the formation of core-shell NR arrays manifesting a clear change in the side walls of the NRs, which become rougher due to CuS shell formation over ZnO NRs. The core-shell heterojunction shows diode behavior with an ideality factor of 5.8. The diode shows a very fast response time (<0.3 s) towards 365 nm ultraviolet (UV) light, which is an important criterion for the photodetection property. Furthermore, the main advantages of this solution-based method are its simplicity and low cost. This achievement demonstrates that such solution-processed novel core-shell n-p heterojunctions are promising candidates for applications in electro-optic devices.