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Results for “hybrid organic-inorganic layered material”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

A chemical perspective on the chiral induced spin selectivity effect

ABSTRACT This review discusses opportunities in chemistry that are enabled by the chiral induced spin selectivity (CISS) effect. First, the review begins with a brief overview of the seminal studies on CISS. Next, we discuss different chiral material systems whose properties can be tailored through chemical means, with a special emphasis on hybrid organic-inorganic layered materials that exhibit some of the largest spin filtering properties to date. Then, we discuss the promise of CISS for chemical reactions and enantioseparation before concluding.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Optical-Frequency Magnetic Polarizability in a Layered Semiconductor

The optical response of crystals is most commonly attributed to electric dipole interactions between light and matter. Although metamaterials support “artificial” magnetic resonances supported by mesoscale structuring, there are no naturally occurring materials known to exhibit a nonzero optical-frequency magnetic polarizability. Here, we experimentally demonstrate and quantify a naturally occurring nonzero magnetic polarizability in a layered semiconductor system: two-dimensional (Ruddlesden-Popper phase) hybrid organic-inorganic perovskites. These results demonstrate the only known material with an optical-frequency permeability that differs appreciably from vacuum, informing future efforts to find, synthesize, or exploit atomic-scale optical magnetism for novel optical phenomena such as negative index of refraction and electromagnetic cloaking.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Tailoring the Interfacial Interactions of Porous Polymer Membranes to Accelerate Atomic Layer Deposition: The Latent Path to Antifouling Membranes

Atomic layer deposition (ALD) is a powerful strategy to engineer hybrid organic-inorganic membranes with emergent functionalities. The combination of atomic-level thickness control, a wide materials palette, and unprecedented conformality allows the physiochemical properties (e.g., hydrophilicity) of mesoporous polymer membranes to be precisely tuned. The nucleation of ALD material growth on polymer surfaces relies on Lewis acid-base interactions and remains an overlooked motif with tremendous potential to accelerate ALD nucleation and growth. Strategies to enhance these interactions could enable desirable properties such as antifouling behavior to be imparted on inert polymer surfaces that lack the necessary functional groups for ALD nucleation. Here, in this study, we demonstrate that the reactivity of polyacrylonitrile (PAN) membranes toward ALD metal oxide (MO) precursors with Lewis acid characteristics is enhanced by introducing strong Lewis base functional groups (amidoxime: Am) on the PAN backbone (Am-PAN). The resulting Lewis acid-base interactions accelerate the MO nucleation in Am-PAN and reduce the number of deposition cycles required to achieve hydrophilicity compared with the untreated PAN membrane. Unveiling the reaction mechanism, in situ Fourier transform infrared (FTIR) spectroscopy measurements established enhanced interaction dynamics between the ALD MO precursors and the Am-PAN membrane, unlike the PAN membrane. Spectroscopic ellipsometry and thermogravimetric analysis measurements revealed higher MO loadings in Am-PAN membranes compared to PAN membranes for the same number of ALD cycles. We found that strong Lewis acid-base interactions accelerated the ALD for a range of materials including Al 2 O 3 , TiO 2 , SnO 2 , and ZnO. More broadly, our work demonstrates that tailoring metal-precursor-polymer interactions is a powerful strategy to accelerate and modulate the ALD. We used this design strategy to fabricate Al 2 O 3 -Am-PAN hybrid membranes that showed 2-fold higher antifouling capability compared to pristine PAN membranes prepared with an equivalent number of Al 2 O 3 ALD cycles. Our approach expands the scope of design options for fouling-resistant porous hybrid inorganic-organic membranes and may ultimately reduce the operational costs of water treatment.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Organic-inorganic hybrid perovskite compounds

Photoactive materials comprising organic-inorganic hybrid halide perovskite compounds are provided. Photovoltaic cells and light-emitting devices incorporating the photoactive materials into their light-absorbing and light-emitting layers, respectively, are also provided. The halide perovskites have an amAMX3 perovskite crystal structure, wherein am is an alkyl diamine cation, an aromatic diamine cation, an aromatic azole cation, a cyclic alkyl diamine cation or a hydrazinediium cation; A is a monovalent alkylammonium cation or an alkali metal cation; X is a halide ion or a combination of halide ions; and M is an octahedrally coordinated bivalent metal atom.

Ke, Weijun↗
DOE OSTI2021

Wafer-scale quasi-layered tungstate-doped polypyrrole film with high volumetric capacitance

Layered materials are particularly attractive for supercapacitors because of their unique physical, electrical and chemical properties. In this work, we demonstrate a facile and scalable electrochemical deposition method for wafer-scale synthesis of quasi-layered tungstate-doped polypyrrole films (named TALPy) with controllable thickness and size. The as-prepared TALPy film exhibits a high gravimetric density and excellent volumetric capacitance, exceeding many high-performing carbon- and polymer-based film electrodes. Based on combined results of ex-situ X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS), it is determined that TALPy stores charge through an ion intercalation process accompanied by change in oxidation states of polypyrrole backbone, which is referred as intercalation pseudocapacitance. All these results suggest the great promise of electrochemical deposition as a scalable and controllable bottom-up approach for synthesizing quasi-layered conductive organic-inorganic hybrid films for electrochemical energy storage applications with high volumetric performance.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Superior photo-carrier diffusion dynamics in organic-inorganic hybrid perovskites revealed by spatiotemporal conductivity imaging

Abstract The outstanding performance of organic-inorganic metal trihalide solar cells benefits from the exceptional photo-physical properties of both electrons and holes in the material. Here, we directly probe the free-carrier dynamics in Cs-doped FAPbI 3 thin films by spatiotemporal photoconductivity imaging. Using charge transport layers to selectively quench one type of carriers, we show that the two relaxation times on the order of 1 μs and 10 μs correspond to the lifetimes of electrons and holes in FACsPbI 3 , respectively. Strikingly, the diffusion mapping indicates that the difference in electron/hole lifetimes is largely compensated by their disparate mobility. Consequently, the long diffusion lengths (3~5 μm) of both carriers are comparable to each other, a feature closely related to the unique charge trapping and de-trapping processes in hybrid trihalide perovskites. Our results unveil the origin of superior diffusion dynamics in this material, crucially important for solar-cell applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

Hidden Spin-Valley Locking Stabilizes Nanosecond Spin Polarization in 2D Perovskites

Room-temperature spin control in semiconductors is fundamental to spin-optoelectronics. Although inversion symmetry breaking offers one path for spin control in semiconductors, strong spin dephasing at elevated temperatures remains a persistent limitation. Hidden spin polarization without global symmetry breaking provides another promising material design strategy, but robust spin stabilization from this effect has yet to be experimentally realized. Here we show spin stabilization at room temperature in two-dimensional hybrid organic-inorganic perovskites through hidden spin-valley locking. We use functional non-primary ammonium cations to induce symmetry-breaking distortions in the metal-halide layers, producing giant local spin splitting while preserving global inversion symmetry. Time-resolved circular dichroism measurements reveal optically generated spin-polarized carriers that persist for 686 ps in (AzOH)2PbI4 and 4.7 ns in the lead-free analogue (AzOH)2SnI4 at room temperature, without an external magnetic field. First-principles calculations suggest that these long lifetimes arise from hidden spin valleys, enhanced dielectric screening and reduced spin-orbit-induced scattering in the Sn-based compound. Our design paradigm unlocks inversion-symmetric semiconductors with ultralong spin lifetimes, broadening the materials options for light-driven spin control.

14 SOLAR ENERGY↗
DOE OSTI2021

Super Flexible Transparent Conducting Oxide-Free Organic–Inorganic Hybrid Perovskite Solar Cells with 19.01% Efficiency (Active Area=1 cm 2 )

Highly efficient organic-inorganic hybrid perovskite solar cells (OIHP-SCs) are often fabricated on a transparent conducting oxide (TCO) substrate such as indium tin oxide (ITO). However, the presence of TCOs is disadvantageous to the development of flexible OIHP-SCs due to the brittle nature of ITO which is easily breakable during bending. Herein, a flexible TCO-free OIHP-SC is demonstrated by using lithium bis(trifluoromethane)sulfonimide (Li-TFSI) as a codopant for the single-layer graphene transparent conducting electrode and poly(triarylamine) hole-transporting material (HTM) on a flexible polydimethylsiloxane substrate. The optical and electrical properties of the Li-TFSI-doped graphene substrate are measured by controlling the doping amount and the best conditions for charge extraction are established at a doping concentration of 20 mm Li-TFSI, thus optimizing the device photovoltaic performance. As a result, a highest power conversion efficiency of 19.01% is demonstrated by the flexible TCO-free OIHP-SC devices with an active area of 1 cm 2 . In addition, the flexible TCO-free OIHP-SCs exhibit good bending stability after 5000 bending cycles at radii of 6, 4, and 2 mm and excellent light soaking stability under 1 Sun light intensity over 1000 h as opposed to the poor stability when using poly(3,4-ethylenedioxythiophene) polystyrene sulfonate as the HTM.

14 SOLAR ENERGY↗
DOE OSTI2023

Ce nanoparticles and sol-gel hybrid organic-inorganic coatings maximize corrosion protection in the anodized AA2024-T3

Herein we demonstrate that the corrosion resistance of the AA2024-T3 alloy can be maximized with the application of top protective sol-gel hybrid organic-inorganic coatings. Samples combining Ce nanoparticles within the pores of the anodic layer with the top sol-gel coatings were observed to outperform samples featuring only the coating. This research unravels the self-healing capability against corrosion of the sol-gel coating when Ce nanoparticles are present, as well as a good coverage of defective regions within the oxide by the hybrid layer. This research opens a paradigm aiming at maximizing the corrosion resistance for non-ferrous anodized alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Adsorption-Induced Surface Magnetism

We report the emergence of adsorption-induced magnetism from heterohelicene molecules on a nonmagnetic Cu(100) surface. Spin-polarized low-energy electron microscopy measurements reveal spin-dependent electron reflectivity for enantiopure 7,12,17-trioxa[11]helicene (TO[11]H) monolayers, indicating the formation of a spin-polarized state localized in the topmost copper layer. Control experiments on clean Cu(100) and TO[11]H on highly oriented pyrolytic graphite show no such effect, excluding artifacts and chirality-induced spin selectivity as origins. Spin-polarized density functional theory calculations with hybrid functionals attribute the magnetism to strong chemisorption, which induces hybridization between the molecular HOMO and copper s- and d-states, driving asymmetric spin-polarized charge redistribution at the interface. An extended Newns-Anderson-Grimley model incorporating on-site Coulomb repulsion in Cu d-orbitals reproduces the emergence of interfacial spin polarization above a threshold interaction strength, highlighting the key roles of hybridization parameters and Coulomb correlation. These findings reveal a mechanism for inducing magnetism at molecule-metal interfaces without inherently magnetic components, offering avenues for engineering spin-polarized states in organic-inorganic hybrid systems.

Hubbard model↗
DOE OSTI2021

Layered Double Perovskites

Successful strategies for the design of crystalline materials with useful function are frequently based on the systematic tuning of chemical composition within a given structural family. Perovskites with the formula ABX 3 , perhaps the best-known example of such a family, have a vast range of elements on A, B, and X sites, which are associated with a similarly vast range of functionality. Layered double perovskites (LDPs), a subset of this family, are obtained by suitable slicing and restacking of the perovskite structure, with the additional design feature of ordered cations and/or anions. In addition to inorganic LDPs, we also discuss hybrid (organic-inorganic) LDPs here, where the A-site cation is a protonated organic amine. Several examples of inorganic LDPs are presented with a discussion of their ferroic, magnetic, and optical properties. The emerging area of hybrid LDPs is particularly rich and is leading to exciting discoveries of new compounds with unique structures and fascinating optoelectronic properties. We provide context for what is important to consider when designing new materials and conclude with a discussion of future opportunities in the broad LDP area.

Materials Science↗
DOE OSTI2025

Hydrotrope-enabled high concentration aqueous electrolytes for reversible and sustainable iron metal anodes

Iron metal-based energy storage devices hold great potential in stationary grid-scale sustainable energy due to the high theoretical specific capacity, ultralow cost, and abundance of iron. However, their practical deployment is limited by the poor reversibility of iron plating and stripping, as well as competitive hydrogen evolution. Here we introduce the concept of hydrotropy into iron electrolytes by developing an environmentally friendly and cost-effective high-concentration ferrous sulfate electrolyte using urea as a hydrotropic agent. The designed electrolyte increases the Coulombic efficiency of iron metal electrodes to approximately 96.5%, compared with ~84.6% for the dilute electrolyte. Molecular dynamics simulations and Raman spectroscopy illustrate that urea regulates the competitive coordination of anions and urea in the iron solvation sheath, while reconstructing the hydrogen-bond network in free water molecules. This reduces the activity of both solvated and free water, thereby alleviating hydrogen evolution. Moreover, the coordinated anions and urea molecules facilitate the in-situ formation of an organic-inorganic hybrid protective layer on the metallic iron, establishing a physical barrier against water and promoting homogeneous interfacial reactions. This work demonstrates an appealing opportunity to design cost-effective and high-performance electrolytes and propels the practical application of iron metal-based energy storage devices.

Feng, Guangxia [Stanford Univ., CA (United States)↗
DOE OSTI2021

Effect of heterostructure engineering on electronic structure and transport properties of two-dimensional halide perovskites

Organic-inorganic halide perovskite solar cells have attracted much attention due to their low-cost fabrication, flexibility, and high-power conversion efficiency. More recent efforts show that the reduction from three- to two-dimensions (2D) of organic–inorganic halide perovskites promises an exciting opportunity to tune their electronic properties. Here, we explore the effect of reduced dimensionality and heterostructure engineering on the intrinsic material properties, such as energy stability, bandgap and transport properties of 2D hybrid organic–inorganic halide perovskites using first-principles density functional theory. We show that the energy stability of engineered perovskite heterostructures is significantly enhanced. The heterostructures with improved stability also show excellent transport properties similar to their bulk counterparts. Furthermore, these layered chemistries demonstrate the advantage of a broad range of tunable bandgaps and high-absorption coefficient in the visible spectrum. The proposed 2D heterostructured material holds potential for nano-optoelectronic devices as well as for effective photovoltaics.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Perovskite Grown in Gallium Nitride Nanowire Matrix for Stable and High‐Efficiency X‐Ray Detection

High-quality quasi-2D perovskites in a GaN nano-wire matrix are grown to build a 3D hetero-structure for high-performance X-ray sensing. In the 3D hetero-structure, GaN nano-wire matrix serves as an n-type charge collector that can rapidly extract carriers through the bulk film of the perovskite layer. Together with a p-type top electrode, a p–i–n diode with the 3D hetero-structure is built, that exhibits a rectified current–voltage characteristic. After analyzing the interface energy alignment, it is found that the fermi levels of the perovskite and GaN are aligned in the dark, and a quasi-fermi level splits upon illumination, introducing a built-in electrical field at the interface. As a result, strong photo-induced current is observed from the diode without an external field. Finally, the 3D diode for X-ray detection demonstration is used, revealing a sensitivity of 308.9 µC Gy air -1 cm -2 at an exceptionally low applied field of 0.125 V µm -1 . The X-ray-induced signal from the 3D diode is stable after 155 cycles of X-ray irradiation under a constant electric field. This demonstration informs a new 3D architecture for high-performance X-ray sensing, and it shows that GaN is a robust n-type interface for perovskite optoelectronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Interspace and Vacancy Modulation: Promoting the Zinc Storage of an Alcohol-Based Organic–Inorganic Cathode in a Water–Organic Electrolyte

Expanding interspace and introducing vacancies are desired to promote the mobility of Zn ions and unlock the inactive sites of layered cathodes. However, this two-point modulation has not yet been achieved simultaneously in vanadium phosphate. Here, in this work, a strategy is proposed for fabricating an alcohol-based organic–inorganic hybrid material, VO 1–x PO 4 ·0.56C 6 H 14 O 4 , to realize the conjoint modulation of the d-interspace and oxygen vacancies. Peculiar triglycol molecules with an inclined orientation in the interlayer also boost the improvement in the conversion rate of V 5+ to V 4+ and the intensity of the P—O bond. Their synergism can ensure steerable adjustment for intercalation kinetics and electron transport, as well as realize high chemical reactivity and redox-center optimization, leading to at least 200% increase in capacity. Using a water–organic electrolyte, the designed Zn-ion batteries with an ultrahigh-rate profile deliver a long-term durability (fivefold greater than pristine material) and an excellent energy density of ≈142 Wh kg –1 (including masses of cathode and anode), thereby substantially outstripping most of the recently reported state-of-the-art zinc-ion batteries. This work proves the feasibility to realize the two-point modulation by using organic intercalants for exploiting high-performance new 2D materials.

25 ENERGY STORAGE↗
DOE OSTI2024

Birefringent Color Filter by Layered Metal‐Organic Chalcogenides: In‐Plane Anisotropy and Odd/Even Effect

Anisotropic 2D materials are gaining interest recently as building blocks for angular‐dependent optical/electrical devices. However, the fundamental understanding of their structure‐property‐relationship is limited, which hinders further modulation of their unique characteristics via structure tailoring. Here the in‐plane structural anisotropy and the tunable optical/electrical properties of a series of radiation‐sensitive (X‐ray, e‐beam) metal‐organic chalcogenide (MOC) single crystals are comprehensively revealed with ligands of variable length/parity. Their monoclinic crystallography is determined at atomic resolution by a simple method that couples X‐ray/electron diffraction with first‐principles calculations. The in‐plane inorganic backbone of the MOCs exhibits a strong lattice anisotropy with odd/even alternations, which originates from that of the out‐of‐plane organic motifs via organic/inorganic accommodation. Such structural anisotropy is implied mechanically by the preferred orientation of crystal cleavage. It triggers a maximum ≈8 × distinction of in‐plane electrical conductivity of the semiconducting MOCs, plus a distinct birefringence (maximum Δn ≈ 0.03) with a dispersive orientation of dielectric axes, which rotate up to 25.7° from UV to visible‐light regime, inspiring an emerging pathway for color filtering via single crystal rotation. Such in‐plane optical characteristics also exhibit odd/even alternation and can be flexibly tuned by the designable out‐of‐plane ligands.

birefringence↗
DOE OSTI2022

Ultrafast Excitonic Response in Two-Dimensional Hybrid Perovskites Driven by Intense Midinfrared Pulses

Two-dimensional organic-inorganic hybrid perovskites (2DHPs) are natural quantum-well-like materials, in which strong quantum and dielectric confinement effects due to the organic spacers give rise to tightly bound excitons with large binding energy. To examine the mutual interactions between the organic spacer cations and the inorganic charge-residing octahedral framework in 2DHPs, here we perform femtosecond pump-probe spectroscopy by direct vibrational pumping of the organic spacers, followed by a visible-to-ultraviolet probe covering their excitonic resonances. Measurements on prototypical lead-bromide based 2DHP compounds, (BA) 2 ⁢PbBr 4 and (BA) 2 ⁢(FA)⁢Pb 2 ⁢Br 7 (BA+ = butylammonium; FA + = formamidinium), reveal two distinct regimes of the temporal response. The first regime is dominated by a pump-induced transient expansion of the organic spacer layers that reduces the exciton oscillator strength, whereas the second regime arises from pump-induced lattice heating effects primarily associated with a spectral shift of the exciton energy. In addition, vibrational excitation enhances the biexciton emission, which we attribute to a stronger intralayer exciton confinement as well as vibrationally induced exciton detrapping from defect states. Finally, our study provides fundamental insights regarding the impact of organic spacers on excitons in 2DHPs, as well as the excited-state dynamics and vibrational energy dissipation in these structurally diverse materials.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Structure and electronic tunability of acene alkylamine based layered hybrid organic-inorganic perovskites from first principles

Twelve layered hybrid organic-inorganic perovskites combining oligoacene derivatives [phenylmethylammonium (PMA), naphthylmethylammonium (NMA), anthrylmethylammonium (AMA), and tetrylmethylammonium (TMA)] and lead halides (Cl - , Br - , and I - anions) are investigated by first-principles density functional theory (DFT), showing broad, rational tunability of band gap, quantum well type, and spin-dependent energy band properties. Six compounds are known from previous syntheses and are used to devise a computational search space for likely low-energy structures. Among the six known compounds, a refined structure is identified for (NMA) 2 ⁢ PbCl 4 and a new, lower-energy structure is suggested for (AMA) 2 ⁢PbCl 4 . The DFT based search methodology is next applied to predict the likely structures for the six unknown compounds. Computationally predicted energy levels for all 12 compounds from spin-orbit coupled hybrid DFT reveal tunable type I quantum well alignments, with frontier orbitals located on the inorganic component, on the organic component, or on both, as controlled by cation and anion selection. In conclusion, several structures spontaneously break local and global inversion symmetry, causing strong spin splitting of the conduction bands [up to 0.12 eV for (PMA) 2 ⁢PbCl 4 ] and showing potential for spin-dependent transport properties and future spintronic and tunable chiroptical applications.

36 MATERIALS SCIENCE↗