Regensburg 2004 – scientific programme
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SYOH: Organic and Hybrid Systems for Future Electronics
SYOH 5: Poster
SYOH 5.40: Poster
Thursday, March 11, 2004, 18:00–21:00, B
Leuco bases as dopants for n-type doping of organic thin films — •Fenghong Li, Ansgar Werner, Martin Pfeiffer und Karl Leo — Institut fuer Angewandte Photophysik, TU Dresden, 01062
Doping of organic thin films by insertion of electron donating (n dopant) or electron accepting (p dopant) atoms or moleculars has been shown to be efficient and to increase film conductivity by several orders of magnitude. N-type doping of electron transport materials with alkali metal atoms has also been extensively reported, but these metals may not be suitable for controlled doping. Now, organic molecules as dopants for n-type doping are also investigated for device applications.
We demonstrated that the cationic dye pyronin B (pyB) greatly increased the conductivity of electron transporting materials /1/. Based on this finding, we further studied other triphenylmethane dyes as dopants for fullerene C60 used in solar cells. For instance, conductivities up to 7.9· 10−3 S/cm were achieved when C60 was doped with Crystal Violet. Such high conductivities render the ohmic losses in the electron transport layers of organic solar cells neglectable.
As in the case of pyronin B, the leuco bases of the corresponding dyes are formed by during sublimation. We found that these leuco bases become re-oxidized to the cation in the layer by electron transfer to electron accepting matrices, leading to the doping effect.
/1/ A.G. Werner, F. Li et al Appl. Phys. Lett., 82, 4495