A Molybdenum Dithiolene Complex as p-Dopant for Hole-Transport Materials: A Multitechnique Experimental and Theoretical Investigation

Molybdenum tris-[1,2-bis(trifluromethyl)ethane-1,2-dithiolene] (Mo(tfd)(3)) is investigated its it P-dopant For organic semiconductor . With all electron affinity of 5.6 eV, Mo(tfd)(3) is a strong oxidizing agent suitable for the oxidation of several hole transport materials (HTMs). Ultraviolet photoemission spectroscopy confirms p-doping of the standard HTM N,N'-di-[(1-napthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine (alpha-NPD). Strong enhancement of hole injection ill alpha-NPD/Au interfaces is achieved via doping-induced formation of it narrow depletion region in the organic semiconductor. Variable-temperature current-voltage measurements on alpha-NPD: Mo(tfd)(3) (0-3.8 mol%) yield an activation energy for polaron transport that decreases with increasing doping concentration, which is consistent with the effect Of the doping-induced filling of traps oil hopping transport. Good stability of Mo(tfd)(3) Versus diffusion in the alpha-NPD host matrix is demonstrated by Rutherford backscattering for temperatures up to 110 degrees C. Density functional theory (DFT) calculations arc performed to obtain in geometries and electronic structures of isolated neutral and anionic MO(tfd)(3) molecules.