Efficiency of charge recombination in organic light emitting diodes Original Research Article

A Monte Carlo simulation study has been conducted to examine the efficiency of bimolecular charge recombination as a function of the binding energy Δ Eexc of the exciton state formed upon collapse of an electron-hole pair. It is found that for Δ Eexc > 0.2 eV the yield is constant and in accord with Langevinʹs recombination formalism but decreases sharply for lower binding energy. Analytic considerations are presented relating the rate of bimolecular charge recombination to the electron and hole current densities in single layer devices as well as in bilayer devices featuring interfacial charge accumulation. The conditions are examined under which the yield is independent of the driving current.