Vibronic coupling constants of hole-transporting molecules, TPF and CBP, are estimated. Despite the planar structure of TPF, the calculated vibronic coupling constants are close to those of nonplanar TPD. The origin of the vibronic couplings in TPF is investigated employing the vibronic coupling density analysis. Based on a Hubbard Hamiltonian, electron-hole interactions are found to be crucial in the vibronic couplings. A large difference of on-site Coulomb interactions, or electron-hole interactions gives rise to a localization of the electron-density difference on a site which can lead to small vibronic couplings. (C) 2011 Elsevier B.V. All rights reserved.