Role of the incipient Anderson transition in electronic energy transfer in mixed organic crystals

The role of disorder in impurity bands in mixed organic crystals is examined in terms of the Anderson model. A coherent potential approximation is used to calculate averaged Green's functions; the L(E) criterion is employed to study the transition in the nature of the eigenstates. The transition is found to take place at a concentration c?, which is qualitatively in agreement with experiments. Our interpretation of the experimental results indicate a continuous variation of the transport properties above c?. Electronic energy transfer experiments in mixed organic solids can give a unique opportunity to study basic questions of localization effects.