Chiral Cation Doping for Modulating Structural Symmetry of 2D Perovskites

Author(s)

Xie, Yi ; Morgenstein, Jack ; Bobay, Benjamin G. G. ; Song, Ruyi ; Caturello, Naidel A. M. S. ; Sercel, Peter C. C. ; Blum, Volker ; Mitzi, David B. B.

• Document type: Journal article
• Source: Journal of the American Chemical Society; v. 145, n. 32, p. 14-pg., 2023-08-02.

Abstract

Cation mixing in two-dimensional(2D) hybrid organic-inorganicperovskite (HOIP) structures represents an important degree of freedomfor modifying organic templating effects and tailoring inorganic structures.However, the limited number of known cation-mixed 2D HOIP systemsgenerally employ a 1:1 cation ratio for stabilizing the 2D perovskitestructure. Here, we demonstrate a chiral-chiral mixed-cationsystem wherein a controlled small amount (<10%) of chiral cationS-2-MeBA (S-2-MeBA = (S)-(-)-2-methylbutylammonium)can be doped into (S-BrMBA)(2)PbI4 (S-BrMBA =(S)-(-)-4-bromo-& alpha;-methylbenzylammonium),modulating the structural symmetry from a higher symmetry (C2) to the lowest symmetry state (P1).This structural change occurs when the concentration of S-2-MeBA,measured by solution nuclear magnetic resonance, exceeds a criticallevel &#xe5f8;specifically, for 1.4 & PLUSMN; 0.6%, the structure remainsas C2, whereas 3.9 & PLUSMN; 1.4% substitution inducesthe structure change to P1 (this structure is stableto & SIM;7% substitution). Atomic occupancy analysis suggests thatone specific S-BrMBA cation site is preferentially substituted byS-2-MeBA in the unit cell. Density functional theory calculationsindicate that the spin splitting along different k-paths can be modulatedby cation doping. A true circular dichroism band at the exciton energyof the 3.9% doping phase shows polarity inversion and a & SIM;45meV blue shift of the Cotton-effect-type line-shape relative to (S-BrMBA)(2)PbI4. A trend toward suppressed melting temperaturewith higher doping concentration is also noted. The chiral cationdoping system and the associated doping-concentration-induced structuraltransition provide a material design strategy for modulating and enhancingthose emergent properties that are sensitive to different types ofsymmetry breaking. (AU)

• FAPESP's process: 20/11560-0 - Computational assessment of the influence of polymorphic domains on the properties of hybrid perovskites
• Grantee: Naidel Antonio Moreira dos Santos Caturello
• Support Opportunities: Scholarships in Brazil - Post-Doctoral