Journal of the American Chemical Society 2009-09-09

Use of a high electron-affinity molybdenum dithiolene complex to p-dope hole-transport layers.

Yabing Qi, Tissa Sajoto, Stephen Barlow, Eung-Gun Kim, Jean-Luc Brédas, Seth R Marder, Antoine Kahn

Index: J. Am. Chem. Soc. 131 , 12530, (2009)

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Abstract

Experimental and theoretical results are presented on the electronic structure of molybdenum tris[1,2-bis(trifluoromethyl) ethane-1,2-dithiolene] (Mo(tfd)(3)), a high electron-affinity organometallic complex that constitutes a promising candidate as a p-dopant for organic molecular semiconductors. The electron affinity of the compound, determined via inverse photoemission spectroscopy, is 5.6 eV, which is 0.4 eV larger than that of the commonly used p-dopant F(4)-TCNQ. The LUMO level of Mo(tfd)(3) is calculated to be delocalized over the whole molecule, which is expected to lead to low pinning potential. Efficient p-doping of a standard hole transport material (alpha-NPD) is demonstrated via measurements of Fermi level shifts and enhanced conductivity in alpha-NPD:1% Mo(tfd)(3). Rutherford backscattering measurements show good stability of the three-dimensional Mo(tfd)(3) molecule in the host matrix with respect to diffusion.