Preparation And Testing Of Organic Photodetector Arrays

Organic photodetector（OPD）is a device that converts optical signals into electrical signals.It has the advantages of simple preparation process,light weight,low cost,flexibility and large-area manufacturing potential,and has attracted widespread attention in the industry.So far,researchers have made a lot of efforts and achieved corresponding results in the synthesis of organic materials,the study of interface engineering,and the design of device structures.However,in many fields such as environmental monitoring,biomedicine,and imaging sensing,only the development of OPD unit devices cannot meet the actual needs.Looking forward to the future,the OPD array is the only way to promote the commercialization of OPD.Therefore,this paper has carried out a series of work on the array research of OPD,which mainly includes:（1）The preparation and performance of OPD arrays were carried out using indium tin oxide（ITO）with good transparency and conductivity as the bottom electrode.With 4-inch patterned ITO glass as the substrate,it contains a total of 11 arrays.Among them,the scale of a single array is 117×5,and the pixel size is 50μm×235μm.Firstly,the device is prepared,and the device structure adopted is:ITO/PEIE/PBDB-T:ITIC-Th/Mo O₃/Ag.Among them,PEIE is the electron transport layer,and PBDB-T:ITIC-Th is the photoactive layer,which are all formed by spin-coating process;Mo O₃ is the hole transport layer,and Ag is the top electrode,which are all formed by thermal evaporation process.Then,the pixel uniformity was characterized and compared in detail from two aspects of microscopic morphology and photoelectric performance.The characterization results of laser confocal microscopy and atomic force microscopy show that the prepared array has a relatively uniform pixel morphology,and the surface roughness of the photoactive layer film at different regions fluctuates in the range of 3.236-4.181 nm.In addition,the statistical results of the photoelectric performance test show that the dark current density of each pixel of the array is about 1×10^-6 A/cm² and the photocurrent density is about 2×10^-4 A/cm²（650 nm,0.65 m W/cm²）,the photoelectric performance of each pixel has good uniformity.（2）The OPD array was fabricated with CMOS-compatible Al/Ti as the bottom electrode.The array size is 286×214,and the pixel size is 45μm×45μm.The device structure is:Al/Ti/PEIE/PBDB-T:ITIC-Th/Mo O₃/ITO.ITO is the top electrode,and the magnetron sputtering process is used to form the film,and the other functional layers are consistent with the above-mentioned preparation methods.The homogeneity was analyzed by confocal laser microscopy,scanning electron microscopy,and optoelectronic properties.The results show that the prepared array has good uniformity of morphology and photoelectric properties.In addition,the response time of the device was measured,and its rise time and fall time were 15.9μs and 179μs,respectively.（3）Design and manufacture the current signal readout circuit of 16-pixel OPD array device with transimpedance amplifier as the core.In order to realize the readout of the current signal with high signal-to-noise ratio,the circuit adopts the structure of analog switch cascaded transimpedance amplifier.The actual measurement results show that the readout circuit can correctly collect the current signal,and the consistency of each channel is good.