Origin of Ferroelectricity in Two Prototypical Hybrid Organic–Inorganic Perovskites

Abstract

Hybrid organic−inorganic perovskite (HOIP) ferroelectrics are attracting considerable interest because of their high performance, ease of synthesis, and lightweight. However, the intrinsic thermodynamic origins of their ferroelectric transitions remain insufficiently understood. Here, we identify the nature of the ferroelectric phase transitions in displacive [(CH 3 ) 2 NH 2 ][Mn-(N 3 ) 3 ] and order−disorder type [(CH 3 ) 2 NH 2 ][Mn(HCOO) 3 ] via spatially resolved structural analysis and ab initio lattice dynamics calculations. Our results demonstrate that the vibrational entropy change of the extended perovskite lattice drives the ferroelectric transition in the former and also contributes importantly to that of the latter along with the rotational entropy change of the A-site. This finding not only reveals the delicate atomic dynamics in ferroelectric HOIPs but also highlights that both the local and extended fluctuation of the hybrid perovskite lattice can be manipulated for creating ferroelectricity by taking advantages of their abundant atomic, electronic, and phononic degrees of freedom.

Achieving circularly polarized luminescence and large piezoelectric response in hybrid rare-earth double perovskite by a chirality induction strategy

“…33,34 Due to the restriction of Kleinman symmetry, only 18 noncentrosymmetric point groups except three chiral point groups, 422, 432 and 622, have the second harmonic generation (SHG) signal response. 35,36 Therefore, we recorded the temperaturedependent SHG signal response to examine the symmetry breaking of the R1. As shown in Fig.…”

A Van Der Waals Photo‐Ferroelectric Synapse

“…[30][31][32] Van der Waals (vdW) organic-inorganic hybrid halide perovskites emerged around one decade ago as a new class of photovoltaic/optoelectronic material. [33][34][35][36][37][38][39] The unique electronic band structure and defect physics of lead halide systems enable low trap state density and long carrier lifetime. [40][41][42] In addition For hardware artificial intelligence, the central task is to design and develop artificial synapses with needed characteristics.…”

“…Van der Waals (vdW) organic‐inorganic hybrid halide perovskites emerged around one decade ago as a new class of photovoltaic/optoelectronic material. [ 33–39 ] The unique electronic band structure and defect physics of lead halide systems enable low trap state density and long carrier lifetime. [ 40–42 ] In addition to the outstanding transport properties and optical activity, the versatile choices of organic ligands in vdW halide perovskites renders the system a platform for integrating material functionalities, including ferroelectricity.…”

Temperature-Responsive Photoluminescence and Elastic Properties of 1D Lead Halide Perovskites R- and S-(Methylbenzylamine)PbBr3

“…In these LD-MHPs, the distortion of PbX 6 octahedra (X = halogen) significantly influences their photoluminescence (PL) behaviors. Hydrogen bonding, as one of the widely available interactions connecting the inorganic and organic parts, plays an important role in determining the magnitude of octahedral distortion [ 27 , 28 ]. By changing strengths of hydrogen bonds upon external stimuli (i.e., temperature and pressure), the emissive processes and properties of LD-MHPs, such as peak position, intensity, and the full width at half maximum (FWHM) of self-trapped excitons (STEs), could be manipulated [ 29 , 30 , 31 , 32 ].…”