Investigation of C60F36 as low-volatility p-dopant in organic optoelectronic devices

We demonstrate highly efficient small molecule organic light emitting diodes and organic solar cells based on the p-i-n-type structure using the fluorinated fullerene molecule C(60)F(36) as p-dopant in the hole transport layer. We present synthesis, chemical analysis, and energy level investigation of the dopant as well as the conductivity of organic layers consisting of a matrix of N,N,N',N'-tetrakis 4-methoxyphenyl-benzidine(MeO-TPD) or N,N'-[(Diphenyl-N,N'-bis)9, 9,-dimethyl-fluoren-2-yl]-benzidine(BF-DPB) doped by the fullerene compound. State of the art organic p-i-n devices containing C(60)F(36) show efficiencies comparable to devices with the commonly used p-dopant2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F(4)-TCNQ). The advantages of the fullerene based dopant are the low volatility and high thermal stability, which is beneficial for device operation under elevated temperature. These properties make C(60)F(36) highly attractive for the usage as p-dopant in a broad spectrum of organic p-i-n devices like organic light emitting diodes, solar cells, memories, or transistors. (C) 2011 American Institute of Physics. [doi:10.1063/1.3590142]