Temperature Dependence of Charge Transport in Molecular Ensemble Junctions

Abstract

Understanding charge transport across molecule-electrode interfaces is pivotal for the development of organic devices, yet this phenomenon remains elusive. Here, we investigate the temperature dependence of charge transport in molecular junctions consisting of electrode/molecule/electrode stacks subjected to a range of biasing regimes. We analyzed devices with both very low and very high current rectification behavior, and established the conditions yielding a temperature activated transport consistent with a generalized model incorporating the thermally assisted tunneling and incoherent tunneling processes. We have also discovered a regime where the conductance decreased with increasing temperature, in molecular junctions where structural changes within the molecular conformation have been induced by entropic effects. The observed temperature dependence of charge transport provides the first experimental validation of a recently proposed generalized theoretical framework that unifies Landauer formalism with Marcus theory. These measurements have also captured the emergence of new electronic states arising from the co-assembely of molecules containing electron donor and acceptor moieties. Our results decipher key aspects related to charge transport in molecular junctions and leveraging these insights holds significant promise for accelerating the development of more complex devices that exploit electrode-molecule interfaces for tunable functionality.