The Fabrication Of Bottom Electrode Of Organic Photodetector And Research Of Detector Property

Photodetectors have excellent photoelectric detection capabilities and are widely used in various fields,such as:image sensor,health sensor,bionic vision,environmental sensor,optical communications,etc.At present,inorganic photodetectors occupy most of the market share.Inorganic photodetectors have mature preparation technology and stable device performance.However,its single detection band,lack of flexibility,and high cost constraints greatly limit the application of inorganic photodetectors.The organic photodetector combines the research in the field of advanced organic materials with the direction of photoelectricity,and has the advantages of adjustable detection band,low manufacturing cost,light weight,good flexibility,and easy large-area preparation.At the same time,it also has the characteristics of achieving high quantum efficiency,high sensitivity,and minimal response time.These excellent characteristics make organic photodetector devices have great potential in medical monitor,wearable device and other fields,and are favored by researchers in the field.Therefore,this paper first prepared three kinds of Al-based composite metal films（Al/M）and studied their characteristics;then,prepared Mo O₃ films by evaporation process;finally designed and prepared organic photoelectric detection based on Al/M film bottom electrodes,tested and analyzed its photoelectric property.The main work of the thesis is as follows:[1]Three kinds of Al-based composite metal films（Al/M）were prepared,M were Cr,Ni,Ni Cr（Cr:Ni=20:80wt%）,the thickness of the main layer was 130nm,and the thickness of the function adjustment layer was 30nm.The effect of the function adjustment layer on the surface morphology and photoelectric properties of Al/M metal films was studied.The results show that the function adjustment layer changes the surface morphology of the Al/M metal film.The RMS surface roughness of the Al/Cr,Al/Ni,and Al/Ni Cr films are 5.53nm,6.69nm,4.86nm,respectively,which are increased compared with that of the Al film（4.06nm）.The RMS surface roughness of the Al/Ni Cr film is the smallest and the surface is the smoothest.The surface work functions of the Al/Cr,Al/Ni,and Al/Ni Cr films are-4.28e V,-4.19e V,-4.08e V,respectively,which match the energy level of the Zn O electron transport layer.In the 400-1000nm waveband,the reflectivity of Al/Ni Cr films exceeds 50%,while the reflectivity of Al/Cr and Al/Ni films does not exceed 50%.The square resistances of Al/Cr,Al/Ni,and Al/Ni Cr films are 827.5,884.4,and 896.2 mΩ/□,respectively.[2]Designed and prepared organic photodetectors based on the Al/M thin film bottom electrode,and tested and studied their photoelectric performance.First,the Mo O3 film was prepared by evaporation process.The surface morphology characterization,XPS analysis and surface work function test of the prepared film were done.The results show that the surface of the Mo O₃ film is flat and smooth,and the RMS surface roughness is0.496nm.The binding energy of Mo in the film is 233.10e V（3d5/2）and 236.25e V（3d3/2）,existing in the form of Mo⁶⁺.The HOMO energy level of the Mo O₃ film is-5.4e V,matching with the electron acceptor ITIC:Th（HOMO=-5.62e V）,which is conducive to the transmission of light-generated holes.The classical structure device（Mo O₃ film is the hole transport layer）is prepared in the visible light to near-infrared wavelength range In response,under the condition of zero bias voltage and 650nm light source,the specific detection rate of the device exceeds 10¹¹ Jones.The J-V characteristic curves of organic photodetectors based on Al/M film bottom electrodes show that they are of the same photodiode type as devices based on ITO bottom electrodes.The specific detection rates of organic photodetectors based on Al/Cr,Al/Ni,Al/Ni Cr film bottom electrodes under zero bias voltage are 1.77×10¹²,2.17×10¹²,2.90×10¹² Jones,respectively.With the increase of the applied bias voltage,the specific detection rate of the device also decreases;under the same bias voltage,the property of the device based on the Al/M thin film bottom electrode is better than that of the device based on the ITO bottom electrode.The detector based on Al/Ni Cr thin film bottom electrod has the highest specific detection rate,which is 2.96×10¹⁰ Jones under an external bias of-0.5V.