Tuning The Photoelectric Response And Recovery Of Zno Nanorod Array Films

Owing to its special electronic transmission network,ZnO nanorod array film has the superior photoelectric response and photoelectric recovery performance,attracting the great attention of the researchers.Therefore,we mainly study the control of photoelectric response and photoelectric recovery properties of ZnO nanorod array films,as well as the mechanism of the production,consumption and the transport of photoelectric electrons in the ZnO nanorod.Firstly,the defects in ZnO nanorods were adjusted through annealing in air or N₂respectively at different temperatures,then the effects of defect control on the photoelectric properties of ZnO nanorod array films were studied.The results show that with the increase of annealing temperature,the concentration both of oxygen vacancies and zinc vacancies in the ZnO nanorods annealed in the air atmosphere?A-ZnO?increase.While the oxygen vacancy concentration in the ZnO nanorods annealed in the N₂atmosphere?N-ZnO?increases but zinc vacancy concentration decreases with the increasing annealing temperature.Under the illumination of UV light,oxygen vacancies with higher concentration can provide more free electrons through photoioziation.Meanwhile,they also can provide more recombination centers to accelerate the photogenerated charge recombination.Therefore,when the annealing temperature increases,the photoelectric response rate of ZnO nanorod array films decreased.In addition,due to excessive defects involved in electron recapture during the photoelectric response period,thus as annealing temperature increasing,the recovery efficiency of ZnO nanorod array films increases first and then decrease.Meanwhile,the recovery efficiency of A-ZnO is lower than N-ZnO annealed at high temperature.The gas sensing properties to NO₂ gas of ZnO nanorod array films were studied to verify the above deductions.The results show that because of the increase of the concentration of photogenerated electrons,the gas sensitive response of ZnO nanorod array films increases with the increase of annealing temperature under the condition of UV light illumination.At the same time,due to zinc vacancies,the gas sensitive response of A-ZnO is higher than that of N-ZnO.While under the dark condition,the gas sensing response of ZnO nanorod array film is mainly attributed to the intrinsic defects,and zinc vacancies can also capture electrons.Thus,the gas sensitive response of A-ZnO increased with the increase of the annealing temperature,but the gas sensing response of N-ZnO is generally lower than the original ZnO nanorod array film.Finally,we coated ZnO nanorod array films with Mn₃O₄ quantum dots and studied the influences of p-n heterojunction on the photoelectric response and recovery properties of ZnO nanorod array films.The results show that after coated with Mn₃O₄ quantum dots,the photoelectric response of the ZnO nanorod array films is significantly improved by 2to 3 orders of magnitude.Meanwhile,the photoelectric recovery efficiency is enhanced from 2%to nearly 50%.At the same time,with the increase of concentration of Mn₃O₄quantum dots,the photoelectric response of ZnO nanorod array film increases first and then decreases slightly,but the photoelectric recovery efficiency continues to increase.