Dynamic molecular tunnel junctions based on self-assembled monolayers for high tunneling current triboelectricity generation

Efficient conversion of mechanical energy into electric energy with sufficient d.c. current density has great potential for supplying power to electronics. However, conventional triboelectric nanogenerators still face critical challenges mainly due to the high impedance of the polymer-based systems and external rectification. Here, a novel dynamic metal-insulator-metal generator (DMIMG) with a maximum current density of about 7.6 x 10(6) A m(-2) was created by moving a conductive atomic force microscope tip on a formed molecular junction, which is based on triboelectricity and molecular tunneling processes. Finite element simulation and systematic experiments show that a high-density d.c. tunneling current was generated when the non-equilibrium carrier was tribo-excited to move through the molecular monolayer on its own. This proof of concept can also be applied to tunneling current imaging and scaled-up macroscopic energy conversion. This innovative idea may be used to investigate new possibilities for novel materials and device configurations for green energy harvesting methods.