Phase transition to the conducting state in a system of charge-transfer excitons at a donor-acceptor interface

We discuss the phase transition to the conducting state in a system of 2D c harge-transfer excitons (CTEs) at a donor-acceptor interface. The phase tra nsition arises due to strong dipole-dipole repulsion between CTEs which sti mulates the population of free carriers in higher energy states even at low temperature. We use the computer simulations with the random distribution of excitons, with finite lifetime explicitly taken into account. The critic al concentration of CTEs and their energy distribution are calculated. We a lso discuss the possibility of observing the predicted phenomena. (C) 1999 American Institute of Physics. [S1063-7834(99)00705-4].