Bismuth oxyhalide based photo-enhanced triboelectric nanogenerators

Utilizing wide absorption characteristics of a narrow bandgap (-1.8 eV) semiconductor, we report on Bismuth Oxyiodide (BiOI) based photo-enhanced triboelectric nanogenerator (TENG). The potentiostatic deposition of tribo-positive BiOI on transparent, electrically conducting Fluorine doped Indium Tin Oxide (FTO) substrates provides a pathway to exploit concurrently the photo-enhanced charge generation and triboelectric effects. When utilized against tribo-negative polydimethylsiloxane (PDMS) films, under illumination, the BiOI/PDMS TENGs' output was significantly enhanced, wherein an increase of 21% in output voltage, 38% in charge density (26% in short-circuit current density), and 74% in overall power density (from 0.25 Wm(-2) (in dark) and 0.44 Wm(-2) (under illumination)), respectively, was observed. Correspondingly, a dramatic enhancement (from similar to 25 mV to similar to 300 mV) in the average surface potential, termed as surface photovoltage (SPV), for the illuminated BiOI was observed by Kelvin Probe Force Microscopy (KPFM). For an isolated, grounded BiOI/FTO electrode, this enhanced SPV was slow-decaying (similar to 3.5 h) and is attributed to the high dielectric constant, presence of deep surface states and traps within BiOI, and slow charge-exchange with the ambient environment. The work thus not only provides an approach for the enhancement of mechanical-to-electrical efficiency of TENGs by light ab-sorption but can also be utilized for self-powered detection of electromagnetic radiation and photodetectors.

Automated summary

By utilizing Bismuth Oxyiodide as the foundation, combining the triboelectric effect and photo-enhanced charge generation effect, this study successfully improved the output performance of the triboelectric nanogenerator. Additionally, a significant increase in the surface photovoltage of BiOI under illumination was observed, with the reasons for the enhancement effect explained.