Flexible piezoelectric composite thin films have emerged as a transformative platform for next-generation self-powered electronics, soft robotics, and biomedical devices, overcoming the inherent rigidity of traditional ceramics and the limited piezoelectric response of polymers. This comprehensive review systematically examines the significant breakthroughs of the past decade, focusing on synergistic advancements in material innovation and performance optimization. It explores the development of ultrahigh-performance lead-based systems and the substantial progress in eco-friendly lead-free alternatives, including textured ceramics, perovskite derivatives, and two-dimensional materials. The article further details how structural engineering—through architectures such as vertically aligned arrays and multilayer heterostructures—enhances stress transfer and electromechanical coupling. Critical strategies to overcome fundamental limitations are analyzed, encompassing interfacial modifications, self-poling mechanisms, and the burgeoning role of machine learning in accelerating material discovery. The application spectrum spanning wearable sensors, implantable harvesters, and industrial IoT systems is reviewed, highlighting the translation of laboratory innovations toward practical deployment. Finally, persistent challenges and strategic future directions are outlined, emphasizing the need for sustainable materials, hybrid energy systems, and scalable manufacturing to fully realize the potential of intelligent, autonomous piezoelectric technologies.
Wang et al. (Fri,) studied this question.