  We extend our theory of electron--hole recombination in organic light
emitting diodes to investigate the possibility that high energy singlet and
triplet excited states with large electron--hole separations are generated in
such processes, over and above the lowest singlet and triplet excitons. Our
approach involves a time-dependent calculation of the interchain /
intermolecular charge--transfer within model Hamiltonians that explicitly
include electron-electron interactions between the $\pi$-electrons. We show
that the electron--hole recombination reaction can be viewed as a tunneling
process whose cross section depends on both the matrix element of the
interchain part of Hamiltonian and the energy difference between the initial
polaron--pair state and the final neutral states. There occurs a bifurcation of
the electron--hole recombination path in each of the two spin channels that
leads to the generation of both the lowest energy exciton and a specific high
energy charge-transfer state, with the matrix elements favoring the lowest
energy exciton and the energy difference factor favoring the higher energy
state. The overall effect of the electron--electron interactions is to enhance
the singlet:triplet yield ratio over the value of 0.25 predicted from
statistical considerations that are valid only within noninteracting models.
