2D Antiferroelectric Hybrid Perovskite with a Large Breakdown Electric Field And Energy Storage Density

Abstract Energy conversion and storage devices are highly desirable for the sustainable development of human society. Hybrid organic–inorganic perovskites have shown great potential in energy conversion devices including solar cells and photodetectors. However, its potential in energy storage has seldom been explored. Here the crystal structure and electrical properties of the 2D hybrid perovskite (benzylammonium)2PbBr4 (PVK‐Br) are investigated, and the consecutive ferroelectric‐I (FE1) to ferroelectric‐II (FE2) then to antiferroelectric (AFE) transitions that are driven by the orderly alignment of benzylamine and the distortion of [PbBr6] octahedra are found. Furthermore, accompanied by field‐induced AFE to FE transition near room temperature, a large energy storage density of ≈1.7 J cm−3 and a wide working temperature span of ≈70 K are obtained; both of which are among the best in hybrid AFEs. This good energy storage performance is attributed to the large polarization of ≈7.6 µC cm−2 and the high maximum electric field of over 1000 kV cm−1, which, as revealed by theoretical calculations, originate from the cooperative coupling between the [PbBr6] octahedral framework and the benzylamine molecules. The research clarifies the discrepancy in the phase transition character of PVK‐Br and shed light on developing high‐performance energy storage devices based on 2D hybrid perovskite.