On the non-Arrhenius temperature dependence of the interwell electron tunneling rate in quasi two dimensional organic quantum wells

The tunneling rate of photocreated charge carriers between layers in Langmu ir-Blodgett multilayer structures is measured indirectly using the novel te chnique of bimolecular recombination quenching. The tunneling rate is measu red as a function of the applied electrostatic potential difference between the layers as the temperature is varied between 300 and 4 K. This dependen ce is examined in light of the Marcus theory of charge transfer where the e lectrostatic potential replaces the chemical potential as the driving poten tial. The expectations of the Marcus theory are not met and the rate is eff ectively temperature independent, contrary to expectation. Other mechanisms are explored that may explain the lack of temperature dependence including the role of high frequency vibrations and the role of the zero point energ y of those vibrations. The temperature dependence of the exciton dissociati on probability is also examined. (C) 2000 American Institute of Physics. [S 0021-9606(00)71041-5].