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 W m-2 (in dark) and 0.44 W m-2 (under illumination)), respectively, was observed. Correspondingly, a dramatic enhancement (from ~25 mV 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 (~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 absorption but can also be utilized for self-powered detection of electromagnetic radiation and photodetectors.
Bibliographical noteFunding Information:
The authors would like to thank Dr. G. Bhattacharya and Dr. C. Maddi for their help in the acquisition of XRD and XPS spectra, respectively. XPS data collection was performed at NIBEC, Ulster University, supported by EPSRC award EP/R008841/1 . N. Black acknowledges support via the EPSRC Centre for Doctoral Training in Photonic Integration & Advanced Data Storage (Grant no. EP/L015323/01 ).
© 2021 Elsevier Ltd
- Bismuth oxyiodide
- Triboelectric nanogenerators
- Surface photovoltage