Tribovoltaic Performance of TiO2 Thin Films: Crystallinity, Contact Metal, and Thermoelectric Effects

Tribovoltaic devices are attracting increasing attentionas motion-basedenergy harvesters due to the high local current densities that canbe generated. However, while these tribovoltaic devices are beingdeveloped, debate remains surrounding their fundamental mechanism.Here, we fabricate thin films from one of the world's mostcommon oxides, TiO2, and compare the tribovoltaic performanceunder contact with metals of varying work functions, contact areas,and applied pressure. The resultant current density shows little correlationwith the work function of the contact metal and a strong correlationwith the contact area. Considering other effects at the metal-semiconductorinterface, the thermoelectric coefficients of different metals werecalculated, which showed a clear correlation with the tribovoltaiccurrent density. On the microscale, molybdenum showed the highestcurrent density of 192 mA cm(-2). This work showsthe need to consider a variety of mechanisms to understand the tribovoltaiceffect and design future exemplar tribovoltaic devices.

Automated summary

This study examines the tribvovoltic performance of TiO2 thin films in contact with metals of varying work functions. It is found that the current density is not strongly correlated with the work function of the contact metal but is strongly correlated with the contact area. The thermoelectric coefficients of different metals at the metal-semiconductor interface also show a clear correlation with the tribvovoltic current density.