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 C₆₀F₃₆ 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 C₆₀F₃₆ 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 C₆₀F₃₆ 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.