Negative differential conductance and up-converted electroluminescence signal from molecular junction in optical cavity

We report up-conversion in electroluminescence signal from a single-molecular junction under strong coupling with an optical cavity-field. The up-converted signal is due to coupling between the tunneling electrons and the cavity-field, leading to nonlinearities in the electron conduction, giving rise to distinct negative and positive peaks in the differential conductance. The proposed molecular junction is the first model exhibiting up-conversion and negative differential conductance simultaneously. Unlike the previous studies, where the up-conversion takes place due to plasmon assisted transport, in the present case, the up-converted signal arises entirely due to the strong molecule-cavity field coupling within the conducting channel.