Ferroic alternation in methylammonium lead triiodide perovskite

Abstract

Methylammonium lead triiodide (MAPbI 3 ) perovskite has attracted broad interest for solar cells, light-emitting diodes, and so forth. Experiments have captured that the alternative coexistence of polar and nonpolar domains in MAPbI 3 can be switched by photons and phonons. Therefore, it is urgent to clarify the interplay among the crystal space group, polarity, ferroic properties, and switching mechanisms for MAPbI 3 . Herein, we perform a statistical synthesis on ferroelectric and anti-ferroelectric features for tetragonal MAPbI 3 perovskite. The polar and nonpolar domains are ferroelectric with the I4cm space group and anti-ferroelectric with the I4/mcm space group, respectively.The domain wall (DW) separating nonpolar and polar regions is charged. Combining the effects of the electric properties of ferroic domains and the charged DWs, novel switching mechanisms are proposed in which photons and phonons drive alternations between ferroelectric and anti-ferroelectric domains, which provide a reasonable approach to clarify the ambiguous understanding of ferroic behavior for MAPbI 3 perovskite.

The Ferroelectric–Ferroelastic Debate about Metal Halide Perovskites

“…Recently, it has been claimed that the contrast captured in the PFM experiments corresponds to the coexistence of polar (ferro) and nonpolar (antiferro) domains. 48 Arguments are based on structural broken symmetries and statistical synthesis. However, the A-site cation dynamic disorder is totally disregarded.…”

“…Furthermore, even among the supporters of the existence of ferroelectricity in MHPs, the nature of the ferroelectric polarization is not completely clear. Recently, it has been claimed that the contrast captured in the PFM experiments corresponds to the coexistence of polar (ferro) and nonpolar (antiferro) domains . Arguments are based on structural broken symmetries and statistical synthesis.…”

Ferroelasticity Mediated Energy Conversion in Strained Perovskite Films

“…[130] All of these stimuli promote structural variations, inducing variation in the polarization of the entire system. Switching mechanisms between polar and nonpolar domains under photon and phonon stimulation, intending to provide a reasonable approach to clarify the ambiguous understanding of the ferroic behavior of MHPs, have been proposed in a recent work by Qin et al [29] It should be noted that the variation in the polarity of ferroic domains is not homogenous. [16] The unchanged polarity of ferroic domains [19,32,131] may be attributed to the external field being not strong enough to promote polarity variation.…”

“…The fact that the space group of tetragonal MAPbI 3 at room temperature remains under debate, that is, whether it is the polar I4cm group [ 27 ] or non‐polar I4/mcm group, [ 28 ] hinders the determination of the ferroelectricity of MAPbI 3 . [ 29 ] Considering that both I4cm and I4/mcm space groups may possess ferroelasticity, [ 30,31 ] the domain structure observed in MAPbI 3 is believed by many researchers to be ferroelastic domains. [ 19,32 ]…”

“…[1] under debate, that is, whether it is the polar I4cm group [27] or non-polar I4/mcm group, [28] hinders the determination of the ferroelectricity of MAPbI 3 . [29] Considering that both I4cm and I4/mcm space groups may possess ferroelasticity, [30,31] the domain structure observed in MAPbI 3 is believed by many researchers to be ferroelastic domains. [19,32] Ferroelectricity, anti-ferroelectricity, and ferroelasticity are the physical characteristics expressed by MHPs when subjected to external electric and force fields.…”