| The rapid development of the computer and information industry puts higher demands on non-volatile memory,and currently the non-volatile memory flash is close to the development limit.Memristor is one of the most important research directions of the next-generation non-volatile memory.It has been widely fouced by researchers due to its advantages such as simple preparation,small size and easy integration,fast read/write speed,low power consumption and good compatibility with CMOS.Methyl ammonium lead iodine(CH3NH3PbI3,also as MAPbI3)is an organic-inorganic hybrid perovskite material with high carrier mobility,tunable band gap,and flexibility.Moreover,there are many kinds of defects in the film(such as iodine vacancies,methylamine vacancies,etc.),these vacancies and ions will move under the applied electric field,which has a good application prospect in the field of memristor.However,there are common problems such as low substrate coverage,voids and unevenness on the surface in the MAPbI3 film prepared by the spin coating method,which limits its application in electronic devices.In this paper,the modification and growth optimization of MAPbI3 film were carried out by using anti-solvent,adding additive and cation doping.The heterojunction and memory device were prepared from the optimized MAPbI3 film,the main conclusions are as follows:(1)The MAPbI3 film were prepared by spin coating method,then the impact of different anti-solvents(toluene,dichloromethane,ether and ethyl acetate),additive MACl and cationic doping(Co2+,Cu2+,Zn2+ and Mn2+)on film quality were studied.As a result,the MAPbI3 film had good crystallinity and smooth surface without pores with ethyl acetate as anti-solvent.When MACl was added,the crystallinity of the MAPbI3 film is enhanced,the crystal grains change from flakes to granules,and the grain size is reduced and more uniform,which is 100?300 nm.The Mn2+ion doped film has good quality among different cation-doped MAPbI3 films.(2)The MAPbI3/ITO heterojunctions were prepared and its I-V characteristic curves were studied.There was hysteresis and rectification effect in pure methyl ammonium lead iodine heterojunction.After the MAPbI3 film was doped with MACl,the current increased by 5 to 4 orders of magnitude at 5 V voltage,and hysteresis appeard.Among them,the hysteresis index of 4500 rpm is close to 1,and its characteristics are consistent with the complementary resistance phenomenon.(3)The Al/MAPbI3/ITO device memristors were prepared,bipolar memristive phenomenon occurs at different spin coating speed films,with a switching ratio of 103.The set voltage and the reset voltage of the 3000 rpm MAPbI3 film devices were the smallest,1.3 V and-1.8 V,respectively.The formation and fracture of the iodine vacancy pathway is the main cause of sudden changes in resistance and memristive effect.There was no typical memristive phenomenon when the MAC1 was added in MAPbI3 film of Al/MAPbI3/ITO device.Among them,the write-only-read-many feature appeared at 3000 rpm and 4500 rpm MAPbI3 devices,and the 6000 rpm MAPbI3 device showed a complementary resistive switching phenomenon.A layer of FePc film was thermally evaporated on spin-coated MAPbI3 film to prepare an Al/FePc/MAPbI3/ITO device and Co/FePc/MAPbI3/ITO device.Al/FePc/MAPbI3/ITO has no memristive properties,but the WORM features appear after 20V voltage scan and its stability in air is enhanced.The is no current hysteresis in Co/MAPbI3/ITO device.After the device is scanned at 20 V voltage,the I-V curve exhibits complementary resistive switching characteristics. |
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