Research On Construction And Application Of Sensitive,Stable,and Flexible Perovskite Nanowire Photodetector

As one of the core components of modern optoelectronic industry,photodetectors play an important role in national life,dofence force,and other fields.Photodetectors based on traditional semiconductor materials have many problems,such as complicated manufacturing process,high fabrication cost,complex structure design,unbendable and fragile,which hinder their further development and application.In recent years,perovskite nanowires have shown promising development prospects in the field of photodetectors due to their excellent photoelectric characteristics,good mechanical flexibility,and low-cost preparation.However,perovskite nanowire photodetectors still have some problems,such as low performance and poor stability.Based on these,in this paper,through the passivation effect of organic molecules,the defect density of states of perovskite nanowires is reduced and the carrier transport process is improved,and the regulation of perovskite dimension,perovskite nanowire photodetectors with high sensitivity and stability are obtained.The main research contents are as follows:（1）The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate（BMIMBF₄）was used to reduce the trap state densities of methylammonium lead triiodide（MAPb I₃）nanowires and improve the corresponding charge carrier transport,and obtained MAPb I₃ nanowire photodetector with detectivity（D^*）,and linear dynamic range（LDR）of 2.06×10¹³ Jones,and 160 d B,respectively.Under the unpackaged condition,the device has no performance attenuation after being placed in the air（humidity 30～40%）for more than 5000 hours.Compared with the commercial silicon photodiode S2386,the device exhibits higher diffuse imaging capability under the same measure conditions.（2）The influence of alkyl chain lengths of ionic liquids on the stability and performance of MAPb I₃ nanowire photodetectors was clarified.With the increase of the alkyl chain lengths of ionic liquids,the trap state densities of MAPb I₃ nanowires decrease and the carrier transports increase,which improves the stability and performance of the corresponding devices.The responsivity（R）and D^*of the device based on the ionic liquid 1-octyl-3-methylimidazolium tetrafluoroborate（OMIMBF₄）with the longest alkyl chain are 209.2 A/W and 1.36×10¹⁴ Jones,respectively.Without package protection,the device maintains 100%of its initial performance after being stored in the air（humidity 35～45%）for 4200 hours.Under the same conditions,the weak-light diffuse reflection imaging resolution of the device reaches 6 p W,which is more than 6000 times higher than that of the commercial silicon photodiode S2386（36.4 n W）.（3）The phenylethylamine iodine（PEAI）was doped into MAPb I₃ nanowires to reduce the dimension of MAPb I₃ and construct two-dimensional（2D）/three-dimensional（3D）perovskite structure,which blocks the corrosion of water oxygen molecules in the air to MAPb I₃ and inhibits the dark exciton transmission in MAPb I₃,leading to the improved stability,noise current(I_noise),and D^*of the corresponding devices.The I_noise and D^*of the device reach 7.61×10^-15 A/Hz^1/2 and1.51×10¹⁴ Jones,respectively.The unencapsulated device shows no performance change after exposure to the air（humidity 45～55%）for 2880 hours.The flexible device based on PEAI doping has no performance degradation after bending 200cycles in the various bending directions and 1000 cycles in the fixed bending directions.（4）The 2D/3D perovskite nanowires were secondary doped with p-trifluorobenzylamine iodine（CF₃-BZAI）to reduce the lattice defects in 2D/3D perovskite nanowires,improve the exciton transport in 2D/3D perovskite nanowires,and enhance the stability and performance of the corresponding devices.The noise equivalent power（NEP）and D^*of the device are 1.08×10^-16 W/Hz^1/2 and 2.28×10¹⁴Jones,respectively.Meanwhile,the device possesses a resolution of 319μW photoplethysmography（PPG）signal detection capability.The performance of the unpackaged device is not descended after stored in the air（humidity 45～55%）for3600 hours.