The Preparation Of Zinc Oxide Nanocrystals And Phosphorene Quantum Dots And Their Photodetectors

Polycrystalline film photodetectors often suffer from several drawbacks,such as uncontrollable defect species,grain boundary scattering and surface oxygen trapping/detrapping,hindering their practical applications in high performance UV photodetection.In this work,we induce acceptor-type zinc vacancy(V_Zn)defect in zero dimensional ZnO nanocrystals by a dual thermal annealing process,which have been closely examined by defect sensitive electron paramagnetic resonance?EPR?technique.The optimization of annealing parameters can well tune the V_Zn concentration and induce a considerable self-powered behavior,which is believed to be result from ionized acceptor enhanced charge separation.On the other aspect,the capping of metallic Zn can lead to the formation of abundant interface conducting channels for the highly-efficient charge transport and extraction.The optimized responsivity is enhanced from 5.3×10-3 to 15.3 A W^-1 and the average rise and decay time remains at 36.6 ms and 101.8 ms.Conductive atomic force microscopy?CAFM?confirms a uniform photocurrent distribution in the annealed polycrystalline films,suggesting the significance of synergies of lattice defects and grain boundary conductive channels.This study unambiguously demonstrates a new route to engineer the photodetection in nanocrystalline oxides,providing a promising prospect for future low-cost,low-power-consumption micro/nano optoelectronic devices.Wide-spectrum photodetectors have extremely broad application prospects.This study is concentrated on the in-situ derived phosphorene/ZnO hybrid heterojunction nanoparticles and their application in broadband-response photodetector.The photodetector based on ZB nanofilms consistently exhibits broadband response from ultraviolet?380 nm?to near infrared?785 nm?,with fast response time and high responsivity.The fast response time and high responsivity are attributed to the enhanced photon harvesting,a fast exciton separation.In addition,the device exhibits an excellent stability under air exposure compared with reported pristine phosphorene-based photodetectors.The superior antioxidation capacity is believed to originate from the fast transfer of lone-pair electrons of phosphorene.The unique assembly of phosphorene/ZnO nano-heterojunctions paves the way toward multifunctional broadband-response photodetector techniques.