EFFICIENCY OF CHARGE RECOMBINATION IN ORGANIC LIGHT-EMITTING-DIODES

A Monte Carlo simulation study has been conducted to examine the effic iency of bimolecular charge recombination as a function of the binding energy Delta E(exc) of the exciton state formed upon collapse of an e lectron-hole pair. It is found that for Delta E(exc) > 0.2 eV the yiel d is constant and in accord with Langevin's recombination formalism bu t decreases sharply for lower binding energy. Analytic considerations are presented relating the rate of bimolecular charge recombination to the electron arid hole current densities in single layer devices as w ell as in bilayer devices featuring interfacial charge accumulation. T he conditions are examined under which the yield is independent of the driving current.