Fabrication Of Organic Single Crystal Photodetector And Their Application In High-performance Integrated Device

Single crystals of organic small molecular semiconductors with high carrier mobility and long exciton diffusion length,are regarded as ideal materials for high-performance photodetectors.However,working mechanism of organic single crystal-based photodetectors is not clear enough,the performance of devices is inferior and they less used in integrated devices.The research of this thesis mainly focused on the organic single crystals-based photodetectors.Then,based on the detailed investigation of their working mechanism,we expanded their applications in integrated devices such as artificial visual perception system and wavelength detection.1.Based on the performance study of organic small molecule Dif-TES-ADT single crystal phototransistor,the test results of the hydroxyl in interface and ambient atmosphere?air,vacuum,nitrogen and oxygen?show that the device can lead to an apparent persistent photoconductivity?PPC?at the semiconductor/insulating interface with hydroxyl group and under the presence of oxygen in the environment,that is,the devices maintain high conductivity for a long time after the light is removed.However,the conductivity of the device decreases rapidly after illumination when there is no hydroxyl in interface,and under vacuum and nitrogen atmosphere where without oxygen.Moreover,through the home-built multi-field coupling AFM technique based on Scanning Kelvin Probe Microscope?SKPM?test,we found that the surface potential of the material decreased by 635 m V on 10 min after illumination,which confirmed that the photoelectrons were captured by the material.We also study the influencing factors of PPC and realize the controllability of PPC.Through the study of the PPC properties of small molecule organic semiconductors with different molecular structures,it is found that only the p type organic semiconductors with ?-conjugated systems will produce the charge transfer with light excitation and oxygen action,and form the O2-and produce PPC.Finally,using the charge accumulation mechanism in the PPC to prepare phototransistor with high performance,and device can get high responsivity with 108 A W^-1,photoconductive gain of 109,and the specific detectivity with 1018 Jones.At present,these values are the maximum in the field of organic photodetector.Our work provides a reliable theoretical reference for the research of high performance organic phototransistors.2.We adopt 2,8-difluoro-5,11-bis?triethylsilylethynyl?anthradithiophene?Di FTES-ADT?to prepare optical synaptic devices with single crystal array by blade coating method.The photoresponse spectrum of the device covers the UV-visible?250-650 nm?region,with the maximum responsivity of up to 12000 A W^-1,which is comparable to the high level of the current organic photodetectors.Meanwhile,the device also has strong optical storage capacity that the device can still maintain a high current state of 10 ?A and maintain over 104 s after illumination.Optical synaptic devices can achieve shortterm plasticity simulation with a maximum paired pulse facilitation index of 240%,longterm plasticity simulation with the change of synaptic weight up to 106%,and an excellent spike-timing-dependent plasticity simulation with a good symmetry response trend.Furthermore,we integrate the array of optical synaptic devices into an artificial image sensing sensor that contains 10 × 10 optical synaptic device pixels,which realizes the recognition and memory function of the pattern.For the first time,our work shows the application of organic small molecule semiconductors in the field of artificial visual perception,and provides a new opportunity for the application of organic optoelectronic devices in artificial intelligence,such as the implantation of biological medical devices for people with visual impairments.3.We developed an efficient fluid-guided antisolvent vapor-assisted crystallization?FGAVC?method to fabricate large-scale MAPb(I_1-xBr_x)₃?x = 0,0.1,0.2,0.3,0.4?singlecrystalline nanowair?NW?arrays.The preparation of high quality single crystal NW arrays was achieved by the slow crystallization process and the isolation of the growing environment.Significantly,the single crystal NW array-based photodetectors exhibited excellent device performance,such as ultra-wide bandwidth is greater than 0.8 MHz,the ultra-low light detection ability of the special detectivity is high as 1.73 × 10¹¹ Jones,and wide linear dynamic range?150 d B?.It is worth noting that the responsivity of the device is up to 12500 A W^-1,which is the highest value of all organic-inorganic hybrid nanowire photodetectors.More particularly,spectral response of the MAPb(I_1-xBr_x)₃ NW arrays could be sequentially tuned by varying different contents of x = 0-0.4.This character enabled the integration of the NW arrays into a unique system to measure the wavelength?680-780 nm?of incident light.Our work paves the way to realize the application of high performance organic-inorganic hybrid single crystal materials in integrated optoelectronic devices.