Manipulation of Valley Pseudospin by Selective Spin Injection in Chiral Two-Dimensional Perovskite/Monolayer Transition Metal Dichalcogenide Heterostructures

Tuning Exciton Emission via Ferroelectric Polarization at a Heterogeneous Interface between a Monolayer Transition Metal Dichalcogenide and a Perovskite Oxide Membrane

We demonstrate the integration of a thin BaTiO3 (BTO) membrane with monolayer MoSe2 in a dual-gate device that enables in situ manipulation of the BTO ferroelectric polarization with a voltage pulse. While two-dimensional (2D) transition metal dichalcogenides (TMDs) offer remarkable adaptability, their hybrid integration with other families of functional materials beyond the realm of 2D materials has been challenging. Released functional oxide membranes offer a solution for 2D/3D integration via stacking. 2D TMD excitons can serve as a local probe of the ferroelectric polarization in BTO at a heterogeneous interface. Using photoluminescence (PL) of MoSe2 excitons to optically read out the doping level, we find that the relative population of charge carriers in MoSe2 depends sensitively on the ferroelectric polarization. This finding points to a promising avenue for future-generation versatile sensing devices with high sensitivity, fast readout, and diverse applicability for advanced signal processing.

Chiral Induced Spin Selectivity

Since the initial landmark study on the chiral induced spin selectivity (CISS) effect in 1999, considerable experimental and theoretical efforts have been made to understand the physical underpinnings and mechanistic features of this interesting phenomenon. As first formulated, the CISS effect refers to the innate ability of chiral materials to act as spin filters for electron transport; however, more recent experiments demonstrate that displacement currents arising from charge polarization of chiral molecules lead to spin polarization without the need for net charge flow. With its identification of a fundamental connection between chiral symmetry and electron spin in molecules and materials, CISS promises profound and ubiquitous implications for existing technologies and new approaches to answering age old questions, such as the homochiral nature of life. This review begins with a discussion of the different methods for measuring CISS and then provides a comprehensive overview of molecules and materials known to exhibit CISS-based phenomena before proceeding to identify structure-property relations and to delineate the leading theoretical models for the CISS effect. Next, it identifies some implications of CISS in physics, chemistry, and biology. The discussion ends with a critical assessment of the CISS field and some comments on its future outlook.

Lead-Free Chiral Perovskite for High Degree of Circularly Polarized Light Emission and Spin Injection

We report a zero-dimensional (0D) lead-free chiral perovskite (S-/R-MBA)4Bi2I10 with a high degree of circularly polarized light (CPL) emission. Our 0D lead-free chiral perovskite exhibits an average degree of circular polarization (DOCP) of 19.8% at 78 K under linearly polarized laser excitation, and the maximum DOCP can reach 25.8%, which is 40 times higher than the highest DOCP of 0.5% in all reported lead-free chiral perovskites to the best of our knowledge. The high DOCP of (S-/R-MBA)4Bi2I10 is attributed to the free exciton emission with a Huang-Rhys factor of 2.8. In contrast, all the lead-free chiral perovskites in prior reports are dominant by self-trapped exciton in which the spin relaxation reduces DOCP dramatically. Moreover, we realize the manipulation of the valley degree of freedom of monolayer WSe2 by using the spin injection of the 0D chiral lead-free perovskites. Our results provide a new perspective to develop lead-free chiral perovskite devices for CPL light source, spintronics, and valleytronics.

Optically Addressing Exciton Spin and Pseudospin in Nanomaterials for Spintronics Applications

Oriented exciton spins that can be generated and manipulated optically are of interest for a range of applications, including spintronics, quantum information science, and neuromorphic computing architectures. Although materials that host such excitons often lack practical coherence times for use on their own, strategic transduction of the magnetic information across interfaces can combine fast modulation with longer-term storage and readout. Several nanostructure systems have been put forward due to their interesting magneto-optical properties and their possible manipulation using circularly polarized light. These material systems are presented here, namely two-dimensional (2D) systems due to the unique spin-valley coupling properties and quantum dots for their exciton fine structure. 2D magnets are also discussed for their anisotropic spin behavior and extensive 2D magnetic states that are not yet fully understood but could pave the way for emergent techniques of magnetic control. This review also details the experimental and theoretical tools to measure and understand these systems along with a discussion on the progress of optical manipulation of spins and magnetic order transitions.

Room temperature valley polarization via spin selective charge transfer

The two degenerate valleys in transition metal dichalcogenides can be used to store and process information for quantum information science and technology. A major challenge is maintaining valley polarization at room temperature where phonon-induced intervalley scattering is prominent. Here we demonstrate room temperature valley polarization in heterostructures of monolayer MoS2 and naphthylethylammine based one-dimensional chiral lead halide perovskite. By optically exciting the heterostructures with linearly polarized light close to resonance and measuring the helicity resolved photoluminescence, we obtain a degree of polarization of up to -7% and 8% in MoS2/right-handed (R-(+)-) and left-handed (S-(-)-) 1-(1-naphthyl)ethylammonium lead iodide perovskite, respectively. We attribute this to spin selective charge transfer from MoS2 to the chiral perovskites, where the perovskites act as a spin filter due to their chiral nature. Our study provides a simple, yet robust route to obtain room temperature valley polarization, paving the way for practical valleytronics devices.

Strategies and applications of generating spin polarization in organic semiconductors

The advent of spintronics has undoubtedly revolutionized data storage, processing, and sensing applications. Organic semiconductors (OSCs), characterized by long spin relaxation times (>μs) and abundant spin-dependent properties, have emerged as promising materials for advanced spintronic applications. To successfully implement spin-related functions in organic spintronic devices, the four fundamental processes of spin generation, transport, manipulation, and detection form the main building blocks and are commonly in demand. Thereinto, the effective generation of spin polarization in OSCs is a precondition, but in practice, this has not been an easy task. In this context, considerable efforts have been made on this topic, covering novel materials systems, spin-dependent theories, and device fabrication technologies. In this review, we underline recent advances in external spin injection and organic property-induced spin polarization, according to the distinction between the sources of spin polarization. We focused mainly on summarizing and discussing both the physical mechanism and representative research on spin generation in OSCs, especially for various spin injection methods, organic magnetic materials, the chiral-induced spin selectivity effect, and the spinterface effect. Finally, the challenges and prospects that allow this topic to continue to be dynamic were outlined.

Low Detection Limit Circularly Polarized Light Detection Realized by Constructing Chiral Perovskite/Si Heterostructures

Chiral perovskites have been demonstrated as promising candidates for direct circularly polarized light (CPL) detection due to their intrinsic chirality and excellent charge transport ability. However, chiral perovskite-based CPL detectors with both high distinguishability of left- and right-handed optical signals and low detection limit remain unexplored. Here, a heterostructure, (R-MPA)2 MAPb2 I7 /Si (MPA = methylphenethylamine, MA = methylammonium) is constructed, to achieve high-sensitive and low-limit CPL detection. The heterostructures with high crystalline quality and sharp interface exhibit a strong built-in electric field and a suppressed dark current, not only improving the separation and transport of the photogenerated carriers but also laying a foundation for weak CPL signals detection. Consequently, the heterostructure-based CPL detector obtains a high anisotropy factor up to 0.34 with a remarkably low CPL detection limit of 890 nW cm-2 under the self-driven mode. As a pioneering study, this work paves the way for designing high-sensitive CPL detectors that simultaneously have great distinguishing capability and low detection limit of CPL.

Valley-Polarized Interlayer Excitons in 2D Chalcogenide-Halide Perovskite-van der Waals Heterostructures

Interlayer excitons (IXs) in two-dimensional (2D) heterostructures provide an exciting avenue for exploring optoelectronic and valleytronic phenomena. Presently, valleytronic research is limited to transition metal dichalcogenide (TMD) based 2D heterostructure samples, which require strict lattice (mis) match and interlayer twist angle requirements. Here, we explore a 2D heterostructure system with experimental observation of spin-valley layer coupling to realize helicity-resolved IXs, without the requirement of a specific geometric arrangement, i.e., twist angle or specific thermal annealing treatment of the samples in 2D Ruddlesden-Popper (2DRP) halide perovskite/2D TMD heterostructures. Using first-principle calculations, time-resolved and circularly polarized luminescence measurements, we demonstrate that Rashba spin-splitting in 2D perovskites and strongly coupled spin-valley physics in monolayer TMDs render spin-valley-dependent optical selection rules to the IXs. Consequently, a robust valley polarization of ∼14% with a long exciton lifetime of ∼22 ns is obtained in type-II band aligned 2DRP/TMD heterostructure at ∼1.54 eV measured at 80 K. Our work expands the scope for studying spin-valley physics in heterostructures of disparate classes of 2D semiconductors.

Interface Engineering Modulated Valley Polarization in MoS2/hBN Heterostructure

Layered transition metal dichalcogenides (TMDs) provide a favorable research platform for the advancement of spintronics and valleytronics because of their unique spin-valley coupling effect, which is attributed to the absence of inversion symmetry coupled with the presence of time-reversal symmetry. To maneuver the valley pseudospin efficiently is of great importance for the fabrication of conceptual devices in microelectronics. Here, we propose a straightforward way to modulate valley pseudospin with interface engineering. An underlying negative correlation between the quantum yield of photoluminescence and the degree of valley polarization was discovered. Enhanced luminous intensities were observed in the MoS₂/hBN heterostructure but with a low value of valley polarization, which was in stark contrast to those observed in the MoS₂/SiO₂ heterostructure. Based on the steady-state and time-resolved optical measurements, we reveal the correlation between exciton lifetime, luminous efficiency, and valley polarization. Our results emphasize the significance of interface engineering for tailoring valley pseudospin in two-dimensional systems and probably advance the progression of the conceptual devices based on TMDs in spintronics and valleytronics.

Multilayered Alternating-Cations-Intercalation Chiral Hybrid Perovskites with High Circular Polarization Sensitivity

Multilayered chiral hybrid perovskites are highly desired for highly-sensitive circularly polarized light (CPL) detection rooted in their efficient charge transport and strong chiroptical activity. However, designing multilayered chiral hybrid perovskites remains a huge challenge. Here, through pairing achiral ethylamine (EA)-chiral arylamine in the interlayer space, multilayered chiral alternating cations intercalation-type (ACI) hybrid perovskites (R-/S-PPA) EA₂ Pb₂ Br₇ (PPA = 1-phenylpropylamine) are successfully obtained. Significantly, perovskitizer EA extends the thickness of the quantum well and alternating space cation EA greatly alleviates in-plane tilting distortions of adjacent metal halide octahedra, providing fast channels for in-plane carrier transport. Consequently, single-crystal photodetectors of (R-/S-PPA) EA₂ Pb₂ Br₇ exhibit high circular polarization sensitivity with a large anisotropy factor of 0.3, which falls around the highest value among the layered hybrid perovskites. In addition, a fast responding rate (τ_r )of 308 µs and a high CPL-detectivity of 8 × 10¹² Jones are also presented. This work opens up a new perspective to design multilayered chiral hybrid perovskites for high-sensitive CPL detection.

Layer-Number Engineered Momentum-Indirect Interlayer Excitons with Large Spectral Tunability

Interlayer excitons (IXs) in type II van der Waals (vdW) heterostructures are equipped with an oriented permanent dipole moment and long lifetime and thus would allow promising applications in excitonic and optoelectronic devices. However, based on the widely studied heterostructures of transition-metal dichalcogenides (TMDs), IX emission is greatly influenced by the lattice mismatch and geometric misalignment between the constituent layers, increasing the complexity of the device fabrication. Here, we report on the robust momentum-indirect IX emission in TMD/two-dimensional (2D) perovskite vdW heterostructures, which were fabricated without considering the orientation arrangement or momentum mismatch. The IXs show a large diffusion coefficient of ∼10 cm² s^-1, and importantly the IX emission energy can be widely tuned from 1.3 to 1.6 eV via changing the layer number of the 2D perovskite or the thickness of TMD flakes, shedding light on the applications of vdW interface engineering to broad-spectrum optoelectronics.

Direct Detection of Near-Infrared Circularly Polarized Light via Precisely Designed Chiral Perovskite Heterostructures

Chiral metal halide perovskites (CMHPs) have recently shown great potential for direct circularly polarized light (CPL) detection. However, owing to the limited cutoff wavelength edge of these CMHPs, most of the detectors presented thus far are characterized only in the ultraviolet and visible range; CMHPs that target at the near-infrared (NIR) region are still greatly desired. Here, we design a novel CMHP heterostructure, synthesized via solution-processed epitaxial growth of crystalline 3D MAPbI₃ on a 2D chiral (R-BPEA)₂PbI₄ (R-BPEA = (R)-1-(4-bromophenyl)ethylammonium) crystal, and provide the first demonstration of self-powered direct NIR-CPL detection. Compared with individual chiral (R-BPEA)₂PbI₄, the heterostructure not only retains the spin selectivity but also allows much broader absorbance, especially beyond 780 nm, where the (R-BPEA)₂PbI₄ cannot absorb. Furthermore, the built-in electric potential in the heterojunction forces spontaneous separation/transport of photogenerated carriers, enabling the fabrication of devices operating without external energy supply. By making use of the abovementioned advantages, the self-powered CPL detectors of the (R-BPEA)₂PbI₄/MAPbI₃ heterostructures hence show competitive circular polarization sensitivity at 785 nm with a high anisotropy factor of up to 0.25. In addition, a large on/off switching ratio of ∼10⁵ and an impressive detectivity of ∼10¹⁰ Jones are also achieved. As a pioneer study, our results may broaden the material scope for future chiroptical devices based on CMHPs.

Chiral-Molecule-Based Spintronic Devices

Spintronics and molecular chemistry have achieved remarkable achievements separately. Their combination can apply the superiority of molecular diversity to intervene or manipulate the spin-related properties. It inevitably brings in a new type of functional devices with a molecular interface, which has become an emerging field in information storage and processing. Normally, spin polarization has to be realized by magnetic materials as manipulated by magnetic fields. Recently, chiral-induced spin selectivity (CISS) was discovered surprisingly that non-magnetic chiral molecules can generate spin polarization through their structural chirality. Here, the recent progress of integrating the strengths of molecular chemistry and spintronics is reviewed by introducing the experimental results, theoretical models, and device performances of the CISS effect. Compared to normal ferromagnetic metals, CISS originating from a chiral structure has great advantages of high spin polarization, excellent interface, simple preparation process, and low cost. It has the potential to obtain high efficiency of spin injection into metals and semiconductors, getting rid of magnetic fields and ferromagnetic electrodes. The physical mechanisms, unique advantages, and device performances of CISS are sequentially clarified, revealing important issues to current scientific research and industrial applications. This mini-review points out a key technology of information storage for future spintronic devices without magnetic components.

Recent advances in chiral nanomaterials with unique electric and magnetic properties

Research on chiral nanomaterials (NMs) has grown radically with a rapid increase in the number of publications over the past decade. It has attracted a large number of scientists in various fields predominantly because of the emergence of unprecedented electric, optical, and magnetic properties when chirality arises in NMs. For applications, it is particularly informative and fascinating to investigate how chiral NMs interact with electromagnetic waves and magnetic fields, depending on their intrinsic composition properties, atomic distortions, and assembled structures. This review provides an overview of recent advances in chiral NMs, such as semiconducting, metallic, and magnetic nanostructures.

Interlayer excitons in MoSe2/2D perovskite hybrid heterostructures - the interplay between charge and energy transfer

van der Waals crystals have opened a new and exciting chapter in heterostructure research, removing the lattice matching constraint characteristics of epitaxial semiconductors. They provide unprecedented flexibility for heterostructure design. Combining two-dimensional (2D) perovskites with other 2D materials, in particular transition metal dichalcogenides (TMDs), has recently emerged as an intriguing way to design hybrid opto-electronic devices. However, the excitation transfer mechanism between the layers (charge or energy transfer) remains to be elucidated. Here, we investigate PEA₂PbI₄/MoSe₂ and (BA)₂PbI₄/MoSe₂ heterostructures by combining optical spectroscopy and density functional theory (DFT) calculations. We show that band alignment facilitates charge transfer. Namely, holes are transferred from TMDs to 2D perovskites, while the electron transfer is blocked, resulting in the formation of interlayer excitons. Moreover, we show that the energy transfer mechanism can be turned on by an appropriate alignment of the excitonic states, providing a rule of thumb for the deterministic control of the excitation transfer mechanism in TMD/2D-perovskite heterostructures.

Point Defects in Two-Dimensional Ruddlesden-Popper Perovskites Explored with Ab Initio Calculations

Two-dimensional Ruddlesden-Popper (RP) halide perovskites stand out as excellent layered materials with favorable optoelectronic properties for efficient light-emitting, spintronic, and other spin-related applications. However, properties often determined by defects are not well understood in these perovskite systems. This work investigates the ground state electronic structure of commonly formed defects in a typical RP perovskite structure by density functional theory. Our study reveals that these 2D perovskites generally retain their defect tolerance with limited perturbation of the electronic structure in the case of neutral-type point defects. In contrast, donor/acceptor defects induce deep midgap states, potentially causing harm to the material's electronic performance. To retain positive intrinsic properties, the halide vacancies and interstitial defects should be avoided. The observed strong electron localization results in trap states and consequently leads to reduced device performance. This understanding can guide experimental efforts that aim for improved 2D halide perovskite-based device performance.

Stimulating and Manipulating Robust Circularly Polarized Photoluminescence in Achiral Hybrid Perovskites

Circularly polarized light (CPL) is essential for optoelectronic and chiro-spintronic applications. Hybrid perovskites, as star optoelectronic materials, have demonstrated CPL activity, which is, however, mostly limited to chiral perovskites. Here, we develop a simple, general, and efficient strategy to stimulate CPL activity in achiral perovskites, which possess rich species, efficient luminescence, and tunable bandgaps. With the formation of van der Waals heterojunctions between chiral and achiral perovskites, a nonequilibrium spin population and thus CPL activity are realized in achiral perovskites by receiving spin-polarized electrons from chiral perovskites. The polarization degree of room-temperature CPL in achiral perovskites is at least one order of magnitude higher than in chiral ones. The CPL polarization degree and emission wavelengths of achiral perovskites can be flexibly designed by tuning chemical compositions, operating temperature, or excitation wavelengths. We anticipate that unlimited types of achiral perovskites can be endowed with CPL activity, benefiting their applications in integrated CPL sources and detectors.

A Chirality-Based Quantum Leap

There is increasing interest in the study of chiral degrees of freedom occurring in matter and in electromagnetic fields. Opportunities in quantum sciences will likely exploit two main areas that are the focus of this Review: (1) recent observations of the chiral-induced spin selectivity (CISS) effect in chiral molecules and engineered nanomaterials and (2) rapidly evolving nanophotonic strategies designed to amplify chiral light-matter interactions. On the one hand, the CISS effect underpins the observation that charge transport through nanoscopic chiral structures favors a particular electronic spin orientation, resulting in large room-temperature spin polarizations. Observations of the CISS effect suggest opportunities for spin control and for the design and fabrication of room-temperature quantum devices from the bottom up, with atomic-scale precision and molecular modularity. On the other hand, chiral-optical effects that depend on both spin- and orbital-angular momentum of photons could offer key advantages in all-optical and quantum information technologies. In particular, amplification of these chiral light-matter interactions using rationally designed plasmonic and dielectric nanomaterials provide approaches to manipulate light intensity, polarization, and phase in confined nanoscale geometries. Any technology that relies on optimal charge transport, or optical control and readout, including quantum devices for logic, sensing, and storage, may benefit from chiral quantum properties. These properties can be theoretically and experimentally investigated from a quantum information perspective, which has not yet been fully developed. There are uncharted implications for the quantum sciences once chiral couplings can be engineered to control the storage, transduction, and manipulation of quantum information. This forward-looking Review provides a survey of the experimental and theoretical fundamentals of chiral-influenced quantum effects and presents a vision for their possible future roles in enabling room-temperature quantum technologies.

Heterogeneous Integration of Chiral Lead-Chloride Perovskite Crystals with Si Wafer for Boosted Circularly Polarized Light Detection in Solar-Blind Ultraviolet Region

Chiral hybrid organic-inorganic perovskites (HOIPs) have been well developed for circularly polarized light (CPL) detection, while new members that target at solar-blind ultraviolet (UV) region remain completely unexplored. Here, an effective design strategy to demonstrate circular polarization-sensitive solar-blind UV photodetection by growing wide-bandgap chiral HOIP [(R)-MPA]₂ PbCl₄ ((R)-MPA = methylphenethylammonium) single crystals onto silicon wafers, with well-defined heterostructures, is reported. The solid mechanical and electrical connection between the chiral HOIP and silicon wafer results in strong built-in electric field at heterojunction, providing a desirable driving force for separating/transporting carriers generated under CPL excitation at 266 nm. Unexpectedly, during such a transport process, not only the chirality of HOIP crystal is transferred to the heterostructure, but also the circular polarization sensitivity is significantly amplified. Consequently, anisotropy factor of the resultant detectors can reach up to 0.4 at zero bias, which is much higher than that of the pristine single-phase chiral HOIP (≈0.1), reaching the highest among the reported CPL-UV photodetectors. As far as we know, the integration of chiral HOIP crystals with silicon technology is unprecedent, which paves a way for designing boosted-performance CPL detectors in solar-blind UV region as well as for other advanced optoelectronic devices.

Two-Dimensional Hybrid Perovskite-Based van der Waals Heterostructures

Two-dimensional (2D) hybrid perovskites, as newly emerging materials, have become the center of attention in optoelectronic fields within a few years because of their unique optoelectronic properties, including tunable bandgap, long carrier diffusion length, and high absorption coefficient. 2D perovskite-based van der Waals heterostructures via integration of 2D perovskites with other layered materials provide new platforms for many optoelectronic devices with prominent performance, such as photodetectors, light-emitting diodes (LEDs), and phototransistors. In this Perspective, the unique properties of 2D perovskites will be first introduced to explore why this material is attractive and popular. Subsequently, various types of heterostructures based on 2D perovskites will be illustrated, including the heterostructure construction approaches as well as their optical and optoelectronic applications. Finally, potential research directions based on 2D perovskite heterostructures are also proposed.

Electronic and Optical Properties of van der Waals Heterostructures Based on Two-Dimensional Perovskite (PEA)2PbI4 and Black Phosphorus

Combining two-dimensional (2D) perovskites with other 2D materials to form a van der Waals (vdW) heterostructure has emerged as an intriguing way of designing electronic and optoelectronic devices. The structural, electronic, and optical properties of the 2D (PEA)2PbI4/black phosphorus (BP) [PEA:(C4H9NH3)+] vdW heterostructure have been investigated using first-principles calculations. We found that the (PEA)2PbI4/BP heterostructure shows a high stability at room temperature. It is demonstrated that the (PEA)2PbI4/BP heterostructure exhibits a type-I band arrangement with high carrier mobility. Moreover, the band gap and band offset of (PEA)2PbI4/BP can be effectively modulated by an external electric field, and a transition from semiconductor to metal is observed. The band edges of (PEA)2PbI4 and BP in the (PEA)2PbI4/BP heterostructure, which show significant changes with the external electric field, provide further support. Furthermore, the BP layers can enhance the light absorption of the (PEA)2PbI4/BP heterostructures. Our results indicate that the 2D perovskite and BP vdW heterostructures are competitive candidates for the application of low-dimensional photovoltaic and optoelectronic devices.

Great Amplification of Circular Polarization Sensitivity via Heterostructure Engineering of a Chiral Two-Dimensional Hybrid Perovskite Crystal with a Three-Dimensional MAPbI3 Crystal

Chiral hybrid perovskites have brought an unprecedented opportunity for circularly polarized light (CPL) detection. However, the circular polarization sensitivity of such a detector remains extremely low because of the high exciton recombination rate in those single-phase hybrid perovskites. Here, a heterostructure construction strategy is proposed to reduce the electron-hole recombination rate in a chiral hybrid perovskite and achieve CPL detectors with greatly amplified circular polarization sensitivity. A heterostructure crystal, namely, [(R)-MPA]2MAPb2I7/MAPbI3 ((R)-MPA = (R)-methylphenethylamine, MA = methylammonium), has been successfully created by integrating a chiral two-dimensional (2D) perovskite with its three-dimensional counterpart via solution-processed heteroepitaxy. Strikingly, the sharp interface of the as-grown heterostructure crystal facilitates the formation of a built-in electric field, enabling the combined concepts of charge transfer and chirality transfer, which effectively reduces the recombination probability for photogenerated carriers while retaining chiroptical activity of chiral 2D perovskite. Thereby, the resultant CPL detector exhibits significantly amplified circular polarization sensitivity at zero bias with an impressive anisotropy factor up to 0.67, which is about six times higher than that of the single-phase [(R)-MPA]2MAPb2I7 (0.1). As a proof-of-concept, the strategy we presented here enables a novel path to modulate circular polarization sensitivity and will be helpful to design chiral hybrid perovskites for advanced chiroptical devices.

Recent Progress of Chiral Perovskites: Materials, Synthesis, and Properties

Chiral materials with intrinsic inversion-symmetric structures possess many unique physicochemical features, including circular dichroism, circularly polarized photoluminescence, nonlinear optics, ferroelectricity, and spintronics. Halide perovskites have attracted considerable attention owing to their excellent optical and electrical properties, which are particularly suitable for realizing high power-conversion efficiency in solar cells. Recent studies have shown that chirality can be transferred from chiral organic ligands into halide perovskites and the resultant chiral perovskites combine the advantages of both chiral materials and halide perovskites; this provides an ideal platform to design next-generation optoelectronic and spintronic devices. In this progress report, the most recent advances are summarized in various chemical structures of chiral perovskites, their synthesis strategies, chirality generation mechanisms, and physical properties. Furthermore, the potential chiral-halide-perovskite-based applications are presented and the challenges and prospects of chiral perovskites are discussed. This report outlines the diverse construction strategies of and proposes research directions for chiral halide perovskites; thus, it provides insights into the design of novel chiral perovskites and facilitates investigation of the optoelectronic applications that employ chirality.