Study On The Photodetector Based On Organic-Inorganic Perovskite Materials

In recent years,organic inorganic perovskite photodetector has become the research focus on the field of optoelectronic devices because of their high photoelectric conversion efficiency and simple cheap solution fabrication process.As a semiconductor device,organic inorganic perovskite photodetector not only has the advantage of small size,light weight,low power consumption,reliability and long life,but also has the feature of tunable band gap,infrared-blind and fast response,which has a broad application prospect in the filed of visible light imaging and communication.We fabricate the perovskite planar heterojunction photodiode with inverted structure,which uses CH₃NH₃PbI₃/CH₃NH₃PbI_3-xCl_x as absorption material,uses PCBM as electron transport layer,uses PEDOT:PSS/NiO as hole transport layer.This paper focuses on the responsivity,quantum efficiency,frequency response and cost of perovskite photodetector,which are the most important factors to determine the commercialization of photodetector.We study on the device fabrication,optimization method and performance boost,the main contents are as follows:1)To meet the research needs,we designed and built up a photoelectric test system,and optimized the related parameter,which realizes the measurement of responsivity,quantum efficiency,dark current,transient photocurrent,linear dynamic range.The spectrum measurement range covers 300 nm¹100 nm,and transient photocurrent sampling rate is up to 5 GS/s?2)The fabrication method of the effective layer of perovskite was explored,and the high quality CH₃NH₃PbI₃ thin film was deposition by solvent engineering solution method.The planar inverted heterojunction perovskite photodiode was prepared.The responsivity of the standard CH₃NH₃PbI₃ perovskite photodetector is over 0.28 A/W;by further optimizing the components of the perovskite precursor and using the interface modification method,the responsivity of the standard MAPbI_3-x-x Cl_x perovskite photodetector is as high as 0.39A/W.3)By covering BCP interface layer on perovskite thin film,passivate the interface state of the perovskite film and reduce the traps state density witch the depth of traps state is rang from 0.3 eV to 0.5 eV.The dark current of device reduce about an order of magnitude,thus improves detectivity of our photodetector up to an order of magnitude,and waken the current hysteresis.4)Using organic material PCBM modifies perovskite effective layer.The result indicates that lower concentration??2.5 mg/ml?PCBM modified perovskite can improve the quality of the perovskite effective layer,passivate perovskite traps and defects,especially to the depth of the traps in the range of 0.4 eV⁰.5 eV,inhibit the trap-assisted recombination and improve the transport efficiency of the carriers.5)By shrinking the size of the device from 7 mm² to 0.50 mm²,the corresponding RC time constant is decreased from 450 ns to 134 ns,and the rise time is lease than 200 ns.The RC time constant decreases linearly with the reduction of the size of the device,and have the potential for further reduction.6)Replacing PEDOT:PSS with NiO as the hole transport layer,a similar electrical characteristic such as dark current and resposivity is observed.Compared with the organic material PEDOT:PSS,inorganic material NiO has the advantages of high hole mobility,wider band-gap,low fabrication cost and easy to synthesis.By replacing the material of the hole transport layer,the stability and reliability of the device are further improved.This work gives a experimental guide for further obtain efficient and reliable detectors,lays a theoretical foundation for the measurement and test method about characteristics of optoelectronic device and provides technical reference.We have reason to believe that as one of the most promising optoelectronic materials,organic inorganic perovskite photodetector would be widely used in many aspects of people's life and bring more convenience to our lives.