Impact of photovoltaic effect on performance enhancement of triboelectric nanogenerator for energy harvesting applications

The photo-induced triboelectric nanogenerator (PTENG) has been explored as new generation energy technology, which is enabled by coupling triboelectric and photo-induced charge carriers. PTENG shows a dual work mechanism that is attributed to the synergetic outcome of the photovoltaic and triboelectric effects. This study aims to provide a new strategy for triboelectric nanogenerator devices to achieve high output performance for various smart electronic device applications. Aluminum and n-type silicon were chosen as two different materials for triboelectric measurements. Different techniques were adopted to obtain triboelectric output parameters through the in-house developed triboelectric setup. AFM and Kelvin probe force microscopy imaging techniques were employed to obtain surface roughness and to measure the change in surface potential under the illumination of red (630 nm) laser light. A significant improvement in surface potential of around 40 mV was observed under laser illumination. Triboelectric characterization has been performed to obtain open circuit voltage (VOC) and short circuit current (ISC) with and without light illumination at different speeds of the motor. VOC and Isc were found to be 0.8 V and 2.2 nA, respectively, at 50 rpm speed without any illumination, which was further enhanced to 1.8 V and 5.5 nA, respectively, under the influence of laser light illumination. An increase in the motor speed to 100 rpm results in higher VOC (2.4 V) and higher ISC (3.4 nA) as compared to 50 rpm at no illuminating condition. However, it enhances to 3.4 V and 6.0 nA in illuminating conditions. This is attributed to the generation of charge carrier due to triboelectrification, which is further enhanced because of the photovoltaic effect wherein the generation of electron-hole pair occurs due to the shining of light on the side of semiconductors. These synergetic effects have tremendous potential in sustainable energy harvesting.