Investigation and band gap analysis of pulsed DC magnetron sputtered diamond-like carbon to enhance contact-electrification and durability of triboelectric nanogenerators

The paper details the triboelectric characteristics of diamond-like carbon (DLC) film where a proportioned sp3:sp2 bond ratio is engineered through a patented pulsed DC magnetron sputtering process to achieve a durable commercial energy harvesting material. A triboelectric nanogenerator (TENG) is fabricated by creating the triboelectric interface between DLC and PTFE. The presence and synchronization of σ ̶ σ and σ ̶ π bonds between DLC-PFTE contact surface amplify the electronic cloud overlap between their atoms leading to an enhancement of the triboelectric surface charge density. The inherent hardness and reduced friction achieved through DLC and PTFE respectively prevent the mass transfer, and consequent power loss upon consecutive mechanical contact and achieves a stable electric power output of 141 mW/m2. The DLC durability achieved with PTFE in TENG demonstrates its significant potential as low frequency (1 ̶ 10 Hz) energy harvesting devices and self-/low-power electronic devices and sensors. The paper uniquely contributes to a better understanding of the triboelectrification mechanism by insightfully detailing the band-to-band transition of electrons between the PTFE and DLC tribo-interface, as well as discussing gap and frequency limitation of the tribo-pair on the triboelectric charge yield, storage, transfer, and on the friction layer electric field.