Schottky DC generators with considerable enhanced power output and energy conversion efficiency based on polypyrrole-TiO₂ nanocomposite

Conversion of small mechanical energy into electricity using a Schottky diode is an emerging technology showing great potential in energy harvesting, sensors, and power generation because of the unique direct current (DC) output characteristic. However, it is still challenging to develop Schottky DC generators with ample power output and energy conversion efficiency. Herein, we, for the first time, demonstrate a novel approach to improve the electrical outputs of a Schottky DC generator using a nanocomposite from polypyrrole and titanium dioxide (TiO₂) nanoparticles, a high dielectric material, and aluminum metal. The nanocomposite device showed a current output of 572.70 μA (working area 1.33 cm²) and peak voltage output of 0.84 V with a power density of 0.62 W m⁻² and an energy conversion efficiency of as high as 27.29%, which 48 times higher in current outputs, 167 times higher in power density, and 20 times higher in conversion efficiency in comparison to the device made of pure polypyrrole and aluminum metal. We further showed that the presence of TiO₂ nanoparticles considerably increased the dielectric constant but slightly reduced the dielectric loss of the polypyrrole composite, leading to a reduction in the Schottky junction internal resistance. However, the Schottky barrier height was little changed, the effect mechanism of which is significantly different from the Schottky DC devices made of polypyrrole-containing graphene oxides and nano carbons. These novel understandings may form a novel concept for the development of high-performance Schottky DC generators.