 Piezoelectric materials have been widely used in energy harvesting applications due to their ability to convert mechanical energy into electricity. Recent advances in the field include the development of polymer nanocomposite materials with improved piezoelectric properties, as well as the use of conductive, non-conductive, or hybrid fillers. These materials have shown promise in terms of energy harvesting performance, and have been applied to various types of energy harvesting systems such as wireless devices and self-powered sensors. However, there remain several challenges and opportunities for further research and development.