Performance Optimization Of Perovskite Photodetector Based On MAPbI₃

Lead methylamine iodide(MAPbI3)material has potential application in the field of photodetectors due to its advantages of high carrier mobility,long carrier diffusion length and lifetime,and high optical absorption coefficient.However,due to the inherent film-forming quality and stability of organicinorganic hybrid perovskite films,their wide application in the field of detectors is limited.Based on this,this thesis focuses on the formation of MAPbI3 perovskite film and device interface engineering,and explores,the effect of dimethyl sulfoxide(DMSO)solvent addition on doped perovskite film formation,the effect of sodium acetate(NaAc)doping on perovskite crystallization process,and the difference of zinc oxide-isopropanol(ZnO-IPA)and pure isopropanol(Pure-IPA)during the anti-solvent annealing.Specifically,the research focuses on:Firstly,the effect of solvent components on doped perovskite films was investigated.Due to the good solubility of DMSO,and the strong coordination DMSO and Pb,the perovskite film form a stable intermediate phase and prolong the grain growth time,thereby regulating grain size and crystallinity.Grain size increased from 500 nm to 1200 nm.The photoelectric performance test of the device was carried out,and the test results showed that under the irradiation of incident light(650 nm),compared with pure DMF,the responsivity and detection rate of the device in the self-powered state after the introduction of DMSO were 1.04 A/W and 1.6×1013 Jones,respectively,which increased by 70%and 400%compared with the control group.The results show that DMSO can promote the dissolution of additives and form a stable intermediate phase with MAPbI3,thereby optimizing the quality of perovskite films,thereby improving the photodetection performance of the device.Secondly,the effect of sodium acetate(NaAc)doping on the crystallization process of perovskite was studied.By adding an appropriate amount of NaAc to the perovskite precursor solution,a strong hydrogen bond is formed to make the perovskite mesophase more stable,and the stable interphase can delay the crystallization process of the perovskite film,thereby increasing the grain and optimizing the morphology of the film.Compared to undoped films,the grain size has been increased from 400 nm to 1100 nm.In addition,alkali metal ions can improve the mobility and stability of the device.Therefore,the doped perovskite film has higher crystallinity,fewer defects,and better photoelectric performance of the device.Under the same conditions,the responsiveness of NaAc-doped devices in the self-powered state is 0.92 A/W,which is about 28%higher than that of pure perovskite(Pure-PVK).The detection rate is 1.46×1014 Jones,which is about 40 times higher than Pure-PVK.Finally,anti-solvent engineering is used to optimize the photoelectric performance and stability of perovskite photodetectors.Since the addition of ZnO promotes charge transport and induces crystallization to optimize the crystallinity of the film,the zinc oxide-isopropanol(ZnO-IPA)device obtains better photoelectric performance and improves the stability of the device.The perovskite films prepared by Pure-IPA antisolvent and ZnO-IPA antisolvent had water contact angles of 68.3° and 75.2°respectively after one week of storage,and the increase of water contact angle indicated that the perovskite film prepared by ZnO-IPA antisolvent had better hydrophobicity,thereby slowing down the decomposition rate of perovskite materials in air.The test results show that under the irradiation of incident light(650 nm),the responsivity of ZnO-IPA-treated devices increases by 20%from 0.70 A/W to 0.84 A/W compared with Pure-IPA devices,and the responsivity of ZnO-IPA-treated devices can still reach 75%of the initial state after 28 days,and pure isopropanol(Pure-IPA)devices are only 58%of the initial state.