We compare the geometric and electronic structures of triphenylamine and N,N,'-diphenyl-N,N'-bis(3-methylphenyl)(1,1'-biphenyl)-4,4'-diamine (TPD), two widely used models for hole-transporting molecules. It is seen that triphenylamine and TPD display significantly different properties, the biphenyl segment playing a major role in the latter. We also evaluate, for the two compounds, the reorganization energy involved in the electron-transfer process from a neutral molecule to a hole-containing molecule (radical-cation).