Preparation And Photoelectric Properties Of Self-Powered Solar Blind Ultraviolet Photodetectors Based On Zinc Oxide Nanorods

Zinc oxide nanorods(ZnO NRs)have great potential in the field of selfpowered ultraviolet(UV)detection due to their large specific surface area,high carrier mobility and strong UV absorption capacity.However,the more surface states and defects of ZnO NRs make the composite rate of photogenerated carriers higher and the band gap of ZnO is relatively small,leading to the poor performance of ZnO NRs-based UV photodetectors.In this paper,ZnO NRs are doped and composite heterojunctions are constructed to improve their performance in solar blind UV detection.The main research results are as follows:1.ZnO NRs doped with Ga in seed layer were prepared by hydrothermal method,and the effects of Ga doping concentration on the microstructure of ZnO NRs and photoelectric properties of photodetectors were investigated.The experimental results show that the aspect ratio of ZnO NRs increases from 24 to53 and the absorbance in the UV region increases from 1.40 to 1.92 after the seed layer is Ga-doped.Among them,the ZnO NRs-based photodetector with2% Ga-doped concentration in the seed layer has a large photocurrent at zero bias,which is 5 times higher than that of the undoped detector.2.In order to reduce the recombination of photo-generated carriers to improve the photoresponse performance of ZnO NRs-based detectors,the ZnO NRs/ZnS core-shell structure was prepared by hydrothermal method and the ZnO NRs/ZnS/PEDOT:PSS self-powered photodetector was constructed.The introduction of ZnS effectively broadened the optical band gap of ZnO NRs.Under UV irradiation,ZnO NRs/ZnS-based detector with sulfide reaction time of 1 h exhibits strong self-powered characteristics,and its photocurrent is significantly enhanced compared with that of the ZnO NRs-based detectors.At the same time,the detector shows high UV-Visible rejection ratio and detection rate(1.62×1012 Jones)under UV irradiation.3.In order to enhance the hole transport capability of p-type materials,ptype nickel oxide nanosheets(NiO NSs)were deposited on ZnO NRs by hydrothermal method.The complementary advantages of NiO NSs and PEDOT:PSS organic-inorganic materials were utilized to improve the photoresponse performance of the detectors.The thin nanosheets of NiO are uniformly and tightly wrapped around the surface of ZnO NRs,effectively suppressing the surface states and defects of ZnO NRs.The photocurrent of the ZnO NRs/NiO NSs-based detector was significantly enhanced under UV irradiation with desirable stability and reproducibility.Among them,ZnO NRs/NiO NSs-based detector with NiO hydrothermal growth time of 4 h has a larger photocurrent(3.5 μA)and a higher signal-to-noise ratio,and the UVVisible rejection ratio(28.8)is about 14.4 times higher than that of the ZnO NRs-based photodetector.