Advancements and challenges in molecular/hybrid perovskites for piezoelectric nanogenerator application: A comprehensive review

Molecular perovskites are a class of materials that have attracted considerable attention in recent years due to their unique physical characteristics, structural properties, and diverse applications. These materials are also known as Hybrid Organic-Inorganic Perovskite (HOIP) and are denoted by the general formula ABX3. HOIP materials feature an organic or inorganic molecular cation (A), a metal or molecular cation (B), and a molecular anionic bridging ligand (X). The perovskite structure comprises BX6 octahedra that share corners, forming a three-dimensional network. The remarkable properties of molecular perovskites arise from their intrinsic polarization, resulting from the presence of polar organic cations in hybrid perovskites that possess a constant electric dipole moment. The alignment of these dipoles plays a crucial role in the properties of molecular perovskites. Consequently, this polarization can be harnessed to capture ambient mechanical energy and convert it into electrical energy. This review paper provides a comprehensive overview of molecular perovskites, focusing on their physical characteristics, synthesis methods, and multifunctional applications, particularly in piezoelectric nanogenerators. Furthermore, it addresses the challenges and opportunities associated with boosting their piezoelectric performance and integrating them with nanogenerator technology and flexible devices. Recent advances and breakthroughs in molecular perovskite-based nanogenerators are highlighted, including lead-free, metal-free, double perovskite materials, etc. Finally, the paper proposes future directions and perspectives for further research and innovation in this dynamic field.