Advances in piezoelectric halide perovskites for energy harvesting applications

Halide perovskites have received significant attention as materials for various electronic applications such as photovoltaic cells, photodetectors, light emitting diodes, and sensors, owing to their outstanding and unique properties such as high power conversion efficiency, tunable bandgap, solution based processability, and high absorption coefficient. Recently, in addition, halide perovskites have shown excellent piezoelectric and ferroelectric properties comparable to those of conventional inorganic piezoelectric materials. However, despite the development of various halide perovskite materials with excellent piezoelectric properties, understanding of piezoelectricity in halide perovskites is still further required to realize practical piezoelectric applications. In this review, we present an overview of the piezoelectric and ferroelectric properties of halide perovskites and summarize the recent progress in halide perovskite based piezoelectric energy harvesters. The aim herein is to describe the fundamental understanding of piezoelectricity of various halide perovskite materials and the factors to be considered for the development of high-performance piezoelectric energy harvesters. First, we discuss in detail the crystal structure, and the dielectric, ferroelectric, and piezoelectric properties of the halide perovskite materials depending on the temperature, poling process, illumination, and material compositions to develop high-performance piezoelectric materials. Thereafter, various types of halide perovskites such as thin film and nanocomposite based piezoelectric energy harvesters are introduced. We believe this review article will serve as a useful guide to the design of piezoelectric materials and applications based on halide perovskites.