A Nickel(II) Nitrite Based Molecular Perovskite Ferroelectric

Abstract

The X-site ion in organic-inorganic hybrid ABX 3 perovskites (OHPs) varies from halide ion to bridging linkers like HCOO À ,N 3 À ,NO 2 À ,and CN À .However,nonitrite-based OHP ferroelectrics have been reported so far.N ow,b ased on non-ferroelectric [(CH 3 ) 4 N][Ni(NO 2 ) 3 ], through the combined methodologies of quasi-spherical shape,h ydrogen bonding functionality,a nd H/F substitution, we have successfully synthesized an OHP ferroelectric, [FMeTP][Ni(NO 2 ) 3 ] (FMeTP = N-fluoromethyl tropine). As an unprecedented nitrite-based OHP ferroelectric,t he well-designed [FMeTP]-[Ni(NO 2 ) 3 ]u ndergoes the ferroelectric phase transition at 400 Kwith an Aizu notation of 6/mmmFm, showing multiaxial ferroelectric characteristics.T his work is ag reat step towards not only enriching the molecular ferroelectric families but also accelerating the potential practical applications.Molecular ferroelectrics with cheap,l ightweight, flexible, wearable,a nd environmentally benign characteristics have been amajor research topic in the past decades owing to the potential applications in data storage,p iezoelectric sensors, actuators,a nd nonlinear optical devices. [1] It is their intrinsic structure-property flexibility that brings forth particular interest for molecular design towards new materials with satisfactory ferroelectric performance near or even above room temperature. [2] Nevertheless,d iscovering ar eliable method to control the ordered organization of molecules into apolar lattice and thereby modulate ferroelectricity is an imminent ongoing challenge.R ecently,s everal design strategies involving the selection of molecular building blocks have been developed. [1b,c] Fore xample,t he Zn 2+ /Dy 3+ Schiff base antenna complex and the lower-symmetric quasi-spherical cations modified from the spherical [(CH 3 ) 4 N] + ,1 ,4diazabicyclo[2.2.2]octonium (dabco), or quinuclidinium were found to be promising for constructing molecular ferroelectrics with high Curie point (T c ). [3] Accordingly,w eh ave obtained several outstanding organic-inorganic hybrid perovskite (OHP) ferroelectrics with ageneral formula ABX 3 (A is an organic cation, Bi sametal, and Xi susually halides), such as [(CH 3 ) 3 NCH 2 Cl]MCl 3 (M = Mn, Cd) and [MeHdab-co]RbI 3 ,where the structural transitions arise mainly from the dynamic motions of the A-site moieties. [3b, 4] Remarkably,b y extending the X-site from monatomic anions to bridging linkers like HCOO À , [5] N 3 À , [6] NO 2 À , [7] and CN À , [8] aw ide range of larger and longer organic cations can be accommodated for enriching the OHP families and inducing abundant properties such as ferromagnetism and antiferromagnetism. Fort he classical pseudohalide NO 2 À ,o nly two kinds of inorganic ferroelectrics have been reported, NaNO 2 and MCd(NO 2 ) 3 (M = NH 4 ,K,Rb, Cs,Tl), [9] whereas there are no nitrite-based ferroelectrics in the OHPs.I nt his way,t he earlier work of non-ferroelectric [(CH 3 ) 4 N][Ni(NO 2 ) 3 ], adopting at rigonal centrosymmetric space group P3 m1a t room temper...

Piezoelectric Energy Harvesting Based on Multiaxial Ferroelectrics by Precise Molecular Design

“…For instance, at the areas shown by the blue ellipses, the lateral PFM presents a uniform signal, whereas an obvious bipolar pattern appears in the vertical phase image and is separated by domain walls in the amplitude image, indicating the existence of non-180 domain walls and multiaxial nature of (TMFM)FeBr 4 . 44 The domain structure for the films of (TMCM)FeBr 4 , (TMBM)FeBr 4 , and (TMIM)FeBr 4 are presented in Figures S12-S14. All the PFM mapping provides evidence of the existence of domains with different orientation of polarization in thin films of (TMFM)FeBr 4 , (TMCM)FeBr 4 , (TMBM)FeBr 4 , and (TMIM)FeBr 4 .…”

Centimeter‐Sized Molecular Perovskite Crystal for Efficient X‐Ray Detection

“…[11] Changing the X-site can also affect the properties of molecular perovskite. Xiong et al used the combined methodologies to reduce the molecular symmetry and obtained the first nitrite-based molecular perovskite [FMeTP][Ni(NO 2 ) 3 ] (FMeTP = N-fluoromethyl tropine) with a high ferroelectric phase transition at 400 K. [12] The charge transport is of great significance for device performance. [13] The quest for better understanding of charge transport behavior motivated our exploration of large single crystalline molecular perovskites with high phase purity.…”

Ferroic Halide Perovskite Optoelectronics

“…[ 98 ] An observation of high piezoelectricity in the molecular MHPs makes various potential applications for wearable piezoelectric devices. Furthermore, there are other types of molecular MHP ferroelectrics such as [C 3 H 7 FN] 3 [SnCl 6 ]Cl: antiperovskite structure, [ 99 ] [FMeTP][Ni(NO 2 ) 3 ] (FMeTP = N ‐fluoromethyl tropine), [ 100 ] [(AP)RbBr 3 ] (AP = 3‐ammniopyrrolidinium), [ 95 ] (pyrrolidinium)MnCl 3, 101 MPSnBr 3 (MP = methylphosphonium). [ 102 ] Noteworthily, most ferroelectric studies were performed on single crystals of molecular perovskites not on their thin film counterparts.…”