Electrospun Inorganic Nanowire Arrays For Photodetectors

With special electrical and optical properties,inorganic nanowires were widely applied in fieled effective transistor,transparent electrodes,nanogenerator,flexible display,gas sensor,photodetector,etc.In addition,1D nanostructures possess large surface to volume ratio,and dimensionality,leading to a large responsivity and photoconductive gain.Assemble these functional nanowire into ordered array benefiting to the development of integration and miniaturization for photodetectors.This work,we fabricate nanowire array through electrospinning and focus on the application of photodetectors.1.Based on a literature search,fabricate SnO2 nanowire array using a 'rotating collector' method and 'separate electrode' method.According to the results of the morphology fabricated by this two strategies,method of 'separate electrode' demonstrate a higher arrangement.To compare the photodetecting difference of single crystal SnO2 and polycrystal SnO2 array fabricated by the chemical vapor deposition method and 'separate electrode' method,respectively.The polycrystal nanowire array possesses lower dark current,and high on-off ratio.The electrical transport behavior of SnO2 nanowire array demonstrating a typical behavior of a semiconductor through the low tempreture experiment in the 20K-300K range.Moreover,the polycrstal array possess high specific surface area result from the granular morphology,have response behavior in the room tempreture for CO,H2,and NO2 gas.2.Mixing ZnO and CdO nanomaterials with a complementary bandgap,fabricate a UV-Vis ZnO/CdO heterostructure photodetector.The XRD results indicate that the content of ZnO and CdO could be controlled by adjusting the ratio of precusor.Compared with pure ZnO nanowire array,the mixed heterostructure have a visible photodetecting performance.Meanwhile,the property of the mixed ZnO/CdO did not decay,the on-off ratio is at 104 range,the response and decay time are 4s and 3s,respectively.When the nanowire array were electrospun on the mica substrate,the device demonstrate an excellent bendable ability,its photoelectric property did not decay after 200 cycles bending,and the device possess high transparency,the value of transparency reach 95%in the 400 nm-800 nm range.3.To expand the photodetecting range of the nanowire further,fabricate the ZnO nanowire array/PbS quantum dots device through a ligand exchange process.This heterostructure photodetector have a UV-Vis-NIR photodetecting ability.In additon,this heterostructure photodetector have an accelerate response speed,the response time is decreased to 9s and the decay time decreased to 2 s from origional 22 s.This fast and stable response are also displayed in the Vis and NIR region.Similarly,this nanowire array/quantum dots film demonstrate an excellent bending ability when bending at 180° for 200 cycles.This strategy is further verified on other kind of 1D nanowire and 0D QDs(ZnO/PbSe,CdO/PbS),evidencing the universality of this strategy.4.Co-electrospinning the TiO2 nanotube array to improve the photodetecting performance further.The responsivity and detectivity of the nanotube array are 20 and 250 fold than the TiO2 nanowire array electrospun at the same condition.The response range of TiO2 nanotube heterostructure is expanded to visible range when decorated MAPbI3 QDs.Similarly,this nanotube array/MAPbI3 QDs possessed potentially application in the flexible and transparent device.There was negligible change in the photocurrent of the flexible device via 200 cycles bending under different bending angles.In addition,the transparency could be maintained above 85%in the visible range.