The study of defect state of 2,7-dipyrenyl-9-phenyl-9-pyrenyl fluorene through admittance spectroscopy

• The defect state of DPPPF was studied by admittance spectroscopy.
• Walter, Mott–Schottky and Gaussian models were used.
• This method can be easily applied to other organic semiconductors.

Up to now, the defect state in organic semiconductors has still not been thoroughly studied, especially for the synthesized materials. 2,7-Dipyrenyl-9-phenyl-9-pyrenyl fluorene (DPPPF) was a wonderful synthesized luminescent material in organic electronics. Research has found that the capacitance could reflect the defect state density of the special positions in the depletion region. So in this report, the admittance spectroscopy method was used to study the defect state of DPPPF, during which the Walter and Mott–Schottky models were applied to extract the defect distribution of the material. And in addition, the Gaussian model was used to describe the width of defect state distribution. The result showed that in the DPPPF, the total defect density was about 6 × 1016 cm−3, with the distribution range of 0.32–0.70 eV.