Abstract
Abstract Motivated by the recent work of Santos Lemus and Hirsch and of Pai, Yanus and Stolka on the concentration dependence of hole transport in selected molecularly doped polymers, a Monte Carlo computer study has been conducted. It predicts that transport should in principle exhibit percolative features without, however, showing a well-defined percolation threshold (“pseudo-percolation”). A threshold concentration c 0 for pseudo-percolation will be defined. In a van der Waals solid with exponential wavefunction overlap it decreases with decreasing wavefunction localization because of non-nearest-neighbour jumps. A relation between c 0 and the effective coordination number of the lattice, defined via overlap, is established. For c < c 0 the carrier mobility remains finite and follows approximately a power law, μ∝c m, in accord with experiment. The exponent m increases with increasing localization of the wavefunction which depends on the energetic separation between the transport levels of dopant and host.
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