Chiral-Polar Photovoltage-Driven Efficient Self-Powered Circularly Polarized Light Detection in Three-Dimensional Hybrid Perovskites.

The chiral-polar photovoltaic effect (CPPE), widely present in chiral hybrid perovskites, has brought an unprecedented opportunity for self-powered circularly polarized light (CPL) detection. However, on account of spatial limitations of the crystal structure, currently reported CPPE primarily focuses on low-dimensional hybrid perovskites, which have a low CPL photoresponse restricted by lower carrier transport efficiency compared to three-dimensional perovskites. For the first time, we reported chiral-polar photovoltage-driven efficient self-powered CPL detection in three-dimensional chiral-polar perovskites, MHyPbBr (MHy = Methylhydrazinium).

Advanced Interface Design of Direct-Current Tribovoltaic Nanogenerator.

Tribovoltaic nanogenerator (TVNG), which manifests distinct advantages of direct-current output characteristics and remarkable energy utilization efficiency, is an emerging energy technology relying on the coupling of semiconductor and contact electrification. Dynamic semiconductor interface is the key to TVNGs, as its performance and functionality largely depend on the design and optimization of interface. Hence, with the booming development of TVNGs, it is of great significance to timely update the fundamental understanding of its interface design, which is currently lacking.

Polar Three-dimensional Organic-inorganic Hybrid Perovskite Realize Highly Sensitive Self-driven Ultraviolet Photodetection.

Bulk photovoltaic effect (BPVE) triggered by spontaneous polarization in polar organic-inorganic hybrid perovskites (OIHPs) has brought unprecedented development opportunities for self-powered ultraviolet photodetection. However, the currently reported ultraviolet optoelectronic devices are dominated by low-dimensional hybrid perovskites, in which low carrier mobility limits the photoelectric conversion efficiency. Herein, we report for the first time a polar three-dimensional OIHPs, namely MHyPbBr (1, MHy=methylhydrazine), that achieves high-performance self-driven ultraviolet photodetection.

Dion-Jacobson Perovskites with a Ferroelectrically Switchable Chiral Nonlinear Optical Response.

Electrically switchable second harmonic generation (SHG) is highly valuable in electro-optic modulators, which can be deployed in data communication and quantum optics. Coupling circular dichroism (CD) with an electrically controlled SHG process is advantageous because it enhances the signal transmission bandwidth and security while enabling multiple modulation modes for optical logic. However, ferroelectrically switchable chiral second-order nonlinearity is rarely reported.

Switchable planar chirality and spin texture in highly ordered ferroelectric hybrid perovskite domains.

Chiral organic-inorganic hybrid perovskites offer a promising platform for developing non-linear chiro-optical applications and chiral-induced spin selectivity. Here, we show that achiral hybrid perovskites that have highly ordered ferroelectric domains with orthogonal polarization exhibit planar chirality, as manifested by second harmonic generation with strong circular dichroism. Interestingly, the handedness of the second harmonic generation circular dichroism response can be alternatingly switched between orthogonally polarized domains and domain walls.

Chiral multiferroicity in two-dimensional hybrid organic-inorganic perovskites.

Chiral multiferroics offer remarkable capabilities for controlling quantum devices at multiple levels. However, these materials are rare due to the competing requirements of long-range orders and strict symmetry constraints. In this study, we present experimental evidence that the coexistence of ferroelectric, magnetic orders, and crystallographic chirality is achievable in hybrid organic-inorganic perovskites [(R/S)-β-methylphenethylamine]CuCl.

In-Plane Ferrielectric Order in van der Waals β'-InSe.

van der Waals ferroic materials exhibit rich potential for implementing future generation functional devices. Among these, layered β'-InSe has fascinated researchers with its complex superlattice and domain structures. As opposed to ferroelectric α-InSe, the understanding of β'-InSe ferroic properties remains unclear because ferroelectric, antiferroelectric, and ferroelastic characteristics have been separately reported in this material.

Near-90° Switch in the Polar Axis of Dion-Jacobson Perovskites by Halide Substitution.

Ferroelectricity in two-dimensional hybrid (2D) organic-inorganic perovskites (HOIPs) can be engineered by tuning the chemical composition of the organic or inorganic components to lower the structural symmetry and order-disorder phase change. Less efforts are made toward understanding how the direction of the polar axis is affected by the chemical structure, which directly impacts the anisotropic charge order and nonlinear optical response. To date, the reported ferroelectric 2D Dion-Jacobson (DJ) [PbI] perovskites exhibit exclusively out-of-plane polarization.

Strain-Driven Solid-Solid Crystal Conversion in Chiral Hybrid -Perovskites with Paramagnetic-to-Ferromagnetic Transition.

Hybrid organic-inorganic perovskites (HOIPs) are promising stimuli-responsive materials (SPMs) owing to their molecular softness and tailorable structural dimensionality. The design of mechanically responsive HOIPs requires an in-depth understanding of how lattice strain induces intermolecular rearrangement that impacts physical properties. While chirality transfer from an organic cation to an inorganic lattice is known to influence chiral-optical properties, its effect on strain-induced phase conversion has not been explored.

Growth of bilayer MoTe single crystals with strong non-linear Hall effect.

The reduced symmetry in strong spin-orbit coupling materials such as transition metal ditellurides (TMDTs) gives rise to non-trivial topology, unique spin texture, and large charge-to-spin conversion efficiencies. Bilayer TMDTs are non-centrosymmetric and have unique topological properties compared to monolayer or trilayer, but a controllable way to prepare bilayer MoTe crystal has not been achieved to date. Herein, we achieve the layer-by-layer growth of large-area bilayer and trilayer 1T' MoTe single crystals and centimetre-scale films by a two-stage chemical vapor deposition process.

Intercalation-driven ferroelectric-to-ferroelastic conversion in a layered hybrid perovskite crystal.

Two-dimensional (2D) organic-inorganic hybrid perovskites have attracted intense interests due to their quantum well structure and tunable excitonic properties. As an alternative to the well-studied divalent metal hybrid perovskite based on Pb, Sn and Cu, the trivalent metal-based (eg. Sb with ns2 outer-shell electronic configuration) hybrid perovskite with the AMX formula (A = monovalent cations, M = trivalent metal, X = halide) offer intriguing possibilities for engineering ferroic properties.

Giant room temperature electrocaloric effect in a layered hybrid perovskite ferroelectric: [(CH)CHCHNH]PbCl.

Electrocaloric effect driven by electric fields displays great potential in realizing highly efficient solid-state refrigeration. Nevertheless, most known electrocaloric materials exhibit relatively poor cooling performance near room temperature, which hinders their further applications. The emerging family of hybrid perovskite ferroelectrics, which exhibits superior structural diversity, large heat exchange and broad property tenability, offers an ideal platform.

Bromine-Substitution-Induced High- Two-Dimensional Bilayered Perovskite Photoferroelectric.

High-Curie-temperature () ferroelectrics have exhibited broad applications in optoelectronic devices. Recently, two-dimensional multilayered perovskite ferroelectrics with excellent photoelectric attributes are attracting increasing interest as new systems of photoferroelectrics. However, the effective tuning of the value of a multilayered perovskite photoferroelectric system still remains a huge challenge.

Exploring a lead-free organic-inorganic semiconducting hybrid with above-room-temperature dielectric phase transition.

Recently, organic-inorganic hybrid lead halide perovskites have attracted great attention for optoelectronic applications, such as light-emitting diodes, photovoltaics and optoelectronics. Meanwhile, the flexible organic components of these compounds give rise to a large variety of important functions, such as dielectric phase transitions. However, those containing Pb are harmful to the environment in vast quantities.

(CHNI)AgBiI: a direct-bandgap layered double perovskite based on a short-chain spacer cation for light absorption.

A new iodide layered double perovskite (CHNI)AgBiI (IPAB) has been developed based on a short-chain spacer cation, which is the first homologous compound in iodide double perovskites that adopt the Ruddlesden-Popper structure type. Importantly, IPAB is a promising environmentally friendly alternative to the recently rapidly progressing lead halide semiconductors owing to its narrow direct-bandgap of 1.87 eV and excellent stability.

Exploiting the Bulk Photovoltaic Effect in a 2D Trilayered Hybrid Ferroelectric for Highly Sensitive Polarized Light Detection.

Polarized light detection is attracting increasing attention for its wide applications ranging from optical switches to high-resolution photodetectors. Two-dimensional (2D) hybrid perovskite-type ferroelectrics combining inherent light polarization dependence of bulk photovoltaic effect (BPVE) with excellent semiconducting performance present significant possibilities. Now, the BPVE-driven highly sensitive polarized light detection in a 2D trilayered hybrid perovskite ferroelectric, (allyammonium) (ethylammonium) Pb Br (1), is presented.

Large-Area Exfoliated Lead-Free Perovskite-Derivative Single-Crystalline Membrane for Flexible Low-Defect Photodetectors.

Wide applications of personal consumer electronics have tended to cause a huge demand for smart and portable electronics, featuring mechanical flexibility, lightweight, and environmental friendliness. However, most of the recently reported flexible photodetectors based on microcrystalline and amorphous components commonly suffer from severe drawbacks, including plenty of grains, boundaries, and surface defects. Here, we present a new lead-free chiral perovskite-derivative light absorber of (aminoguanidinium)BiI (), which displays a narrow direct band gap of about 1.

Tunable optical absorption in lead-free perovskite-like hybrids by iodide management.

We present an instructional design strategy to tune the optical absorption ability of organic-inorganic hybrids by managing the internal iodide state. Three bismuth-based hybrids with different internal iodide states were synthesized and display tunable bandgaps from 1.91 eV to 1.

Tailored Synthesis of an Unprecedented Pb-Mn Heterometallic Halide Hybrid with Enhanced Emission.

Organic-inorganic lead halide hybrids have attracted extensive interest in solid-state lighting, due to their superior color tunability and low-cost solution processing. However, the relatively low photoluminescence quantum efficiency (PLQE) is a common issue for most bulk lead halide hybrids. Inspired by the intriguing luminescence properties of heterometallic complexes, we rationally developed an unprecedented two-dimensional (2D) Pb-Mn heterometallic halide hybrid, (CHN)PbMnCl (), through a precisely tailored synthetic approach based on (CHN)PbCl ().

An Unprecedented Biaxial Trilayered Hybrid Perovskite Ferroelectric with Directionally Tunable Photovoltaic Effects.

Multiaxial molecular ferroelectrics, in which multiple-directional switching of spontaneous polarization creates diverse properties, have shown many intriguing advantages, making them indispensable complements to conventional inorganic oxides. Despite recent blooming advances, multiaxial molecular ferroelectric with bulk photovoltaic effects still remains a huge blank. Herein, we report a biaxial lead halide ferroelectric, EAPbBr (1, EA = ethylammonium), which adopts the unique trilayered perovskite motif with a high Curie temperature of ∼384 K.

Exploration of Chiral Organic-Inorganic Hybrid Semiconducting Lead Halides.

Organic-inorganic lead halides have recently emerged as promising alternatives to conventional optoelectronic materials, considering their intriguing physical properties. However, organic-inorganic lead halides featuring chirality are seldom explored. Here, a pair of enantiomorphic organic-inorganic hybrid semiconducting lead halides, (R-C H N )PbBr (1R) and (S-C H N )PbBr (2S), were successfully obtained with the templating of chiral amines.

Two Non-π-Conjugated Deep-UV Nonlinear Optical Sulfates.

The non-π-conjugated sulfate system has long been overlooked as potential deep-UV nonlinear optical (NLO) materials. Here we report two asymmetric anhydrous sulfates, namely, NHNaLi(SO) (Ι) and (NH)NaLi(SO) (Π), which consist of non-π-conjugated [SO] anions. Their single crystals can be readily grown by a facile evaporation method from water solution.

Discovery of an Above-Room-Temperature Antiferroelectric in Two-Dimensional Hybrid Perovskite.

Antiferroelectric materials have been regarded as a promising candidate for electronic energy storage devices, due to their natural double polarization versus electric field ( P- E) hysteresis loops. Currently, two-dimensional organic-inorganic hybrid perovskites with structural diversity and tunability, have received blooming interests, whereas above-room-temperature antiferroelectrics are still unreported in this perovskite system. Herein, for the first time, we successfully acquire a two-dimensional Ruddlesden-Popper hybrid perovskite antiferroelectric, ((CH)CHCHNH)CsPbBr (1), which shows an above-room-temperature Curie temperature at 353 K, trigging by the synergistic dynamic motion of inorganic Cs atoms and organic isobutylammonium cations.

Two-Dimensional Hybrid Perovskite-Type Ferroelectric for Highly Polarization-Sensitive Shortwave Photodetection.

Two-dimensional (2D) materials have been well developed for polarization-sensitive photodetection, while new 2D members used in shortwave region (>2.5 eV) still remain scarce. The family of 2D hybrid perovskite ferroelectrics, in which the coupling of spontaneous polarization ( P) and light benefits dissociation of photoinduced carriers, has shown great potential in this portfolio.

Abrupt Structural Transformation in Asymmetric ABPOF (A = K, Rb, Cs).

An asymmetric structure is the necessary requirement for second-order nonlinear-optical (NLO) materials, which have important applications in modern science and technology. Here we report two isostructural asymmetric compounds, RbBPOF and CsBPOF. Both compounds crystallize in cubic space group P23 (No.