Charge-transfer excitons and χ(2) of molecular monolayers

Abstract

The second-order nonlinear susceptibility χ(2) is calculated for a monolayer of donor–acceptor substituted molecules, using equations of motion which map the problem onto the dynamics of coupled anharmonic (exciton) oscillators. New exciton resonances, which may change in character from Frenkel through charge transfer to Wannier excitons, are predicted as the intermolecular charge-transfer coupling is turned on.