Excellent Switchable Properties, Broad-Band Emission, Ferroelectricity, and High T_c in a Two-Dimensional Hybrid Perovskite: (4,4-DCA)₂PbBr₄ Exploited by H/F Substitution

Abstract

Switchable materials have gained significant attention due to their potential applications in data storage, sensors, and switching devices. Two-dimensional (2D) hybrid perovskites have demonstrated promising prospects for designing switchable materials, where the dynamic motion of the organic components coupled with the distortion of the inorganic framework provides the driving force for triggering multifunctional switchable properties. Herein, through the H/F substitution strategy, we report a polar 2D hybrid lead-based perovskite, (4,4-DCA)2PbBr4 (4,4-DCA = 4,4-difluorocyclohexylammonium) (1), which exhibits dual-stable behavior in a dielectric and second harmonic generation (SHG) response during the reversible phase transition process near the high Curie temperature T c ∼ 409 K. The phase transition temperature is significantly increased by 41 K compared to the corresponding non-fluorinated (CHA)2PbBr4 (CHA = cyclohexylammonium). Remarkably, the material shows rare broad-band yellow emission under UV excitation, attributed to the induction of self-trapped exciton emission by the distortion of the [PbBr6] 4– octahedra, as confirmed by the first-principles analysis. 1 also exhibited ferroelectricity with a saturation polarization value and a small coercive field. This study provides a new insight into the modification of multifunctional switchable materials through the H/F substitution strategy.

Silver/Antimony-Base Multifunctional Double Perovskite with H/F Substitution Enhance Properties

“…Phase transition is usually accompanied by changes in energy, which can be detected through differential scanning calorimetry (DSC) . Collected DSC data in the temperature range of 300–430 K and the results indicate that 1 and 2 undergo a pair of reversible structural phase transitions at 397 ( 1 ) and 404 K ( 2 ) with the increase in temperature, with corresponding thermal hysteresis of 3 and 13 K after cooling (Figure a,b).…”

Novel High-Tc, Broadband-Emission Multifunctional Hybrid Compound: (4,4-DCA)2CdCl4 with Sb Doping Enhances Fluorescence Emission

“…However, 1 exhibits poor fluorescence performance with a quantum yield lower than 1%. Transition dipole moment (TDM) analysis reveals that the electronic transitions from the valence band to the conduction band in 1 are hindered due to the indirect band gap and the additional momentum change involved in the electron transition. − This leads to a reduced transition efficiency and suppresses the intensity of fluorescence emission.…”

Investigating the Structure‐property Relationships of Two Cd‐based Hybrid Multifunctional Compounds with High Tc, Bright Fluorescence and Wide Band‐gap

“…[1][2][3][4] Organic-inorganic hybrid materials have attracted considerable attention due to their versatile structures, efficient energy conversion capabilities, and broad-spectrum fluorescence emission. [5][6][7] Cd-based hybrid compounds often possess high light conversion rate and wide bandgap, making them become promising candidate for white light emission applications. [8][9][10] Organic cation influence fluorescence emission by exerting weak interactions that either induce strain or compress the coordinating environment of the inorganic framework.…”

“…[18][19] Fluorinated organic cations can generate strong intermolecular FÀ F interaction, resulting in enhanced structural rigidity and reduced nonradiative recombination caused by stretching vibration with enhancing intrinsic photoluminescence performance. [7] Hybrid compound with flexible organic long chain is prone to undergo reversible solid-state phase transition due to the dynamic disorder of organic cation under thermal stimuli. [20][21][22] This greatly improve the chance of finding phase transition compounds.…”