Resarch On The Characteristics Of Quaternary Wide-spectrum Organic Photo-detectors Based On P3HT:PC₆₁BM System

Organic photodetectors(OPDs)have the advantages of low production cost,easy large-scale production and wide working range.They are widely used in many fields such as light sensing,environmental monitoring and human-computer interaction.However,the current OPDs of photodiode structure generally have the problems of high working voltage,narrow response spectrum range and poor device performance.In order to solve the above problems,this paper proposes to use bulk heterojunction(BHJ)to prepare high detection rate OPDs covering the visible light wavelength range under low bias.Firstly,three ternary BHJ devices were prepared,in which the active layers were P3HT:PTB7:PC61BM,PTB7:PCPDTBT:PC61BM and P3HT:PCPDTBT:PC61BM.Abs spectroscopy,PL spectroscopy,AFM,TEM,and J-V were used to analyze the effect of the addition of a third component with different mass ratios to the active layer on the optical properties of the film and the electrical properties of OPDs.The study found that although the above ternary OPDs broaden the range of the response spectrum,the response of the device in different bands is poorly balanced.Secondly,the PL spectrum analysis of the interaction between the different donor materials in the above tern ary OPDs found that PTB7 and P3HT,PTB7 and PCPDTBT are exciton dissociation,increasing the total number of excitons in the active layer The energy transfer between P3HT and PCPDTBT improves the dissociation probability of excitons in the active layer.Finally,quaternary OPDs with a mass ratio of 12:2:2:8 of P3HT:PBDT-TT-F:PBDT-TT-C:PC61BM in the active layer were prepared,and the R and EQE of the device under 630,530 and 460 nm light At 340,376,and 315 mA/W and 67,88,and 85%,respectively,D*reached more than 1012 Jones,and successfully prepared high detection rate OPDs covering the visible wavelength range.In summary,the research results show that the use of two components with similar structure instead of a single component can reduce the phase separation between different donor materials and improve the absorption strength of the active layer to different components on the basis of ensuring the microstructure of the active layer;When the ?LUMO of the multi-donor material is greater than 0.3 eV,the exciton dissociation between the donor materials increases the probability of exciton dissociation.When the ?LUMO of the multi-donor material is less than 0.3 eV and the Abs spectrum overlaps with the PL spectrum,the energy transfer between the donor materials increases the total number of excitons in the active layer.This provides a theoretical basis and experimental method for using multiple components to achieve broad spectrum and high detection rate OPDs.