Research On Organometallic Halide Perovskite Photodetector

In recent years,the organometallic halide perovskite materials have attracted wide attention due to its high carrier mobility and high optical absorption coefficient.The efficiency of perovskite solar cells have rose from 3.8%to 22.7%in just a few years.With the deeper studies of perovskite materials,the researches of perovskite photodetectors have also made significant progress.In this paper,perovskite photodetectors with electrode/perovskite/electrode transverse structure were prepared on glass substrates by one-step spin-coating method.Firstly,CH3NH3PbI3 perovskite photodetectors were prepared by PbCl2 as lead source.The suitable preparation parameters were determined by adjusting heating time,precursor solution ratio,different lead sources and different preparation methods.Then,the effects of dropping anti-solvent in the process of spin-coating and adding a small amount of reduced graphene oxide into the precursor solution on the performances of the photodetectors were investigated.Finally,on the basis of the perovskite photodetectors which have been explored in the early stage,the effects of Ag nanoparticles on photodetectors prepared by different lead-source perovskite precursor were investigated.After the above experimental processes,the following conclusions are obtained:(1)When the lead source in the precursor solution is PbCl2,the intensity of the diffraction peak of CH3NH3PbI3 gradually increases with the increase of the heating time,and the crystallization performance gradually improves.The concentrations of PbCl2 in the precursor solution have an impact on the morphology of final film and the performances of the prepared photodetectors.According to the performances of the photodetectors,the optimum concentration of PbCl2 for the preparation of the perovskite photodetectors is 0.8 mol/L in this experiment.(2)When the lead source in the precursor solution is PbI2,with the addtion of chlorobenzene,the morphology of the perovskite film becomes uniform and dense,but the performance of the perovskite photodetector is not improved.By adding a small amount of reduced graphene oxide in the precursor solution,the substrate coverage of the film is improved and effectively the performances of the devices are improved.(3)Under the same test conditions,the responsivity and the normalized detectivity of the perovskite photodetectors prepared by one-step method without the treatment of chlorobenzene are obviously one order of magnitude higher than that of the perovskite photodetectors prepared by two-step method.By using two-step method and dropping chlorobenzene in one-step spin-coating process,uniform and dense perovskite films can be getted.But the performances of these two kinds of photodetectors are not good,which shows uniform and dense perovskite films are not suitable for the transverse-structure perovskite photodetector.(4)The introduction of Ag nanoparticles changes the morphology and crystallinity of the perovskite films prepared by the precursor solution of the two different lead sources and also affectes the performances of photodetectors.After the introduction of Ag nanoparticles,under the same test conditions,the responsivity and the normalized detectivity of the perovskite photodetector with lead source PbCl2 are increased,while the performances of the perovskite photodetector with PbI2 source are decreased.