Application Of Admittance Spectroscopy In Organic Charge Transport Materials

Organic electronics has become a new frontier. The admittance spectroscopy method is applied to the organic semiconductor carrier transport studies in this paper. The admittance spectroscopy method used to study the mobility of N,N’-diphenyl-N, N’-bis(1,1’-biphenyl)-4,4’-diamine (NPB), the trap concentration of tris(8-hydroxyquinoline) aluminum (Alq3), the defect distribution in2,7-pyrenyl-9-phenyl-9-pyrenylfluorene (DPPPF). The main work is as follows:(1)A single-carrier injection admittance model is established by solving the Poisson equation and the current density equation. The hole-only device (ITO/NPB/Ag) was prepared to teste the admittance spectrum, and the experimental data is analyzed with the model. The mobility of NPB is also determined by negative differential susceptance, impedance imaginary part, equivalent scheme, and the results were compared.(2)In consideration of the trap,a single-carrier injection admittance model is established by modifying the model in the chapter2. The electron-only device (ITO/Alq3/Ag) was prepared to teste the admittance spectrum, and the experimental data is analyzed with the new model, from which the trap concentration and the mobility can be determined.(3)A new material DPPPF synthesised by our group is studied by admittance spectroscopy. From the capacitance spectroscopy, the density of defect states and the total concentration of impurities are determined.