Advances in Dielectric Thin Films for Energy Storage Applications, Revealing the Promise of Group IV Binary Oxides

Among currently available energy storage (ES) devices, dielectric capacitors are optimal systems owing to their having the highest power density, high operating voltages, and a long lifetime. Standard high performance ferroelectric-based ES devices are formed of complex composition perovskites and require precision, high-temperature thin film fabrication. The discovery of ferroelectricity in doped HfO2 in 2011 at the nanoscale was potentially game-changing for many modern technologies, such as field effect transistors, non-volatile memory, and ferroelectric tunnel junctions. This is because HfO2 is a well-established material in the semiconductor industry, where it is used as a gate dielectric. On the other hand, (pseudo)binary HfO2 and ZrO2-based materials have received much less attention for ES capacitors, even though antiferro-electric HfO2 and ZrO2-based thin films show strong promise. This Focus Review summarizes the current status of conventional polymer and perovskite ferroic-based ES. It then discusses recent developments in, and proposes new directions for, antiferroelectric and ferroelectric group IV oxides, namely HfO2 and ZrO2-based thin films