Realization of a highly-performing triboelectric nanogenerator utilizing molecular self-assembly

Triboelectric nanogenerator (TENG) is promising as a sustainable power source for energy-autonomous electronics. This work demonstrates for the first time that a highly-performing TENG can be realized by utilizing molecular self-assembly of small molecules. It is found that molecular self-assembly modifies the orbital energy levels of the corresponding tribo-layer that causes reduced energy gap between the tribo-layers for charge transfer. It is also found that an expansion of the electron-rich regions occurs due to molecular self-assembly that in turn increases the probability of the electron cloud/potential well overlap. Both the phenomena result in significantly-enhanced charge transfer between the tribo-positive and tribo-negative layers of a TENG during contact electrification. A low-cost, simple, and straightforward technique that does not require sophisticated equipment is adopted for the molecular self-assembly of a naturally abundant small molecule. Spectroscopic analysis, atomic force microscopy, and electron microscopy reveal that the modified molecules are capable of building high order self-assembled structure. A TENG with a self-assembled layer (SAL-TENG) generated voltage and power density of ∼1340 V and ∼11.75 W m⁻², respectively, as compared with, ∼200 V and ∼3.5 W m⁻² respectively, for another TENG comprising the same molecules but are not self-assembled (NSA-TENG).