Organic-inorganic Research Articles

Preparation of Low-Temperature Solution-Processed High-κ Gate Dielectrics Using Organic-Inorganic TiO2 Hybrid Nanoparticles.

Organic-inorganic hybrid dielectric nanomaterials are vital for OTFT applications due to their unique combination of organic dielectric and inorganic properties. Despite the challenges in preparing stable titania (TiO2) nanoparticles, we successfully synthesized colloidally stable organic-inorganic (O-I) TiO2 hybrid nanoparticles using an amphiphilic polymer as a stabilizer through a low-temperature sol-gel process. The resulting O-I TiO2 hybrid sols exhibited long-term stability and formed a high-quality dielectric layer with a high dielectric constant (κ) and minimal leakage current density. We also addressed the effect of the ethylene oxide chain within the hydrophilic segment of the amphiphilic polymer on the dielectric properties of the coating film derived from O-I TiO2 hybrid sols. Using the O-I TiO2 hybrid dielectric layer with excellent insulating properties enhanced the electrical performance of the gate dielectrics, including superior field-effect mobility and stable operation in OTFT devices. We believe that this study provides a reliable method for the preparation of O-I hybrid TiO2 dielectric materials designed to enhance the operational stability and electrical performance of OTFTs.

Preparation of organic-inorganic hybrid adhesion promoters for polyurethane-metal adhesion and their properties

ABSTRACT This study reports the synthesis of organic-inorganic (O-I) hybrid adhesion promoters, which were synthesized by an in situ sol-gel process, using alkoxysilane functionalized polymer precursor (AFAP) and other alkoxysilanes such as (3-aminopropyl)triethoxysilane (APTES) and (3-glycidyloxypropyl)trimethoxysilane (GPTMS). These adhesion promoters were then applied between polyurethane (PU) and metal substrate for improving adhesive strength between them. In particular, by modifying the input parameters including molecular structure of AFAP, weight ratios between AFAP and alkoxysilane, and r value (molar ratio of H2O/Si), the adhesive strength can be significantly improved by more than twice as high as compared to that of pristine samples without application of O-I hybrid adhesion promoters. It was reported that the combination of (3-aminopropyl)triethoxysilane (APTES) and AFAP synthesized from glycerol propoxylate (Mw = 266 g/mol) and polyethylene glycol (Mw = 300 g/mol) with high r value showed the highest adhesive strength compared to other O-I hybrid adhesion promoters. Additionally, the properties of various hybrid materials such as particle size distribution, touch drying speed, degree of condensation, molecular weight, and adhesive strength were characterized by dynamic light scattering test, 29Si-NMR, MALDI-TOF, and shear strength test.

Spotting Local Environments in Self-Assembled Monolayer-Protected Gold Nanoparticles.

Organic-inorganic (O-I) nanomaterials are versatile platforms for an incredible high number of applications, ranging from heterogeneous catalysis to molecular sensing, cell targeting, imaging, and cancer diagnosis and therapy, just to name a few. Much of their potential stems from the unique control of organic environments around inorganic sites within a single O-I nanomaterial, which allows for new properties that were inaccessible using purely organic or inorganic materials. Structural and mechanistic characterization plays a key role in understanding and rationally designing such hybrid nanoconstructs. Here, we introduce a general methodology to identify and classify local (supra)molecular environments in an archetypal class of O-I nanomaterials, i.e., self-assembled monolayer-protected gold nanoparticles (SAM-AuNPs). By using an atomistic machine-learning guided workflow based on the Smooth Overlap of Atomic Positions (SOAP) descriptor, we analyze a collection of chemically different SAM-AuNPs and detect and compare local environments in a way that is agnostic and automated, i.e., with no need of a priori information and minimal user intervention. In addition, the computational results coupled with experimental electron spin resonance measurements prove that is possible to have more than one local environment inside SAMs, being the thickness of the organic shell and solvation primary factors in the determining number and nature of multiple coexisting environments. These indications are extended to complex mixed hydrophilic-hydrophobic SAMs. This work demonstrates that it is possible to spot and compare local molecular environments in SAM-AuNPs exploiting atomistic machine-learning approaches, establishes ground rules to control them, and holds the potential for the rational design of O-I nanomaterials instructed from data.

Anchoring Vertical Dipole to Enable Efficient Charge Extraction for High-Performance Perovskite Solar Cells.

Perovskite solar cells (PSCs) via two‐step sequential method have received great attention in recent years due to their high reproducibility and low processing costs. However, the relatively high trap‐state density and poor charge carrier extraction efficiency pose challenges. Herein, highly efficient and stable PSCs via a two‐step sequential method are fabricated using organic—inorganic (OI) complexes as multifunctional interlayers. In addition to reduce the under‐coordinated Pb2+ ions related trap states by forming interactions with the functional groups, the complexes interlayer tends to form dipole moment which can enhance the built‐in electric field, thus facilitating charge carrier extraction. Consequently, with rational molecular design, the resulting devices with a vertical dipole moment that parallels with the built‐in electric field yield a champion efficiency of 23.55% with negligible hysteresis. More importantly, the hydrophobicity of the (OI) complexes contributes to an excellent ambient stability of the resulting device with 91% of initial efficiency maintained after 3000 h storage.

Femtosecond optical nonlinearities and ultrafast absorption dynamics of colloidal 2D organometal halide ((C12H25–NH3)2PbI4) nanoparticles and thin films

Layered 2D Inorganic-Organic (IO) hybrid semiconductors of the type (R–NH3)2PbI4 have shown tremendous potential applications in various photonics and optoelectronic devices. In this work, femtosecond laser induced optical nonlinearities and excited state charge carrier dynamics of organometal halide (C12H25–NH3)2PbI4 (C12PI) 2D colloidal nanoparticles (NPs) and the thin film counterpart are investigated. These colloidal 2D NPs of sizes ∼9 nm, show third-order optical nonlinearity having two-photon absorption coefficient (2PA) (β∼26-23 cm/GW) and positive nonlinear refractive index (n2∼7.6 × 10−2 cm2/GW), while thin films show β∼78–134 cm/GW and n2∼0.003-0.2 × 10−2 cm2/GW. The origins of two-photon induced absorption and Kerr-type refractive nonlinearity are as a result of induced molecular polarization and charge transfer effects between organic cation (C12H25–NH3)+ and inorganic anion (PbI6 octahedra). The ultrafast transient absorption spectral studies demonstrate the room-temperature Mott-type exciton excited-state charge carrier dynamics and charge carrier recombination features. The laser pump intensity dependent transient absorption spectral (TAS) features reveal wide information about ground state bleaching (GSB∼510 nm, ΔA<0 with decay of 28.2–3.2 ps) along with a photo-induced absorption (PIA∼476 nm, ΔA>0, with decay of 22–6.3 ps) regions. The systematic studies of optical nonlinearities and ultrafast absorption dynamics of 2D IO hybrid semiconductor colloidal nanoparticles and thin film will provide a new platform for advanced photonics and ultrafast optical switching devices applications.

Hydrophobic coatings prepared using various dipodal silane-functionalized polymer precursors

This study introduces synthetic methodology to develop hydrophobic surfaces. Hydrophobic surfaces are fabricated via cross-linking of inorganic-organic hybrids, prepared from dipodal alkoxysilane-functionalized urethane precursors (AFUS). The inorganic-organic (I-O) hybrids are synthesized by co-hydrolysis and co-condensation of various precursors. The hybrid solutions are then used to fabricate hydrophobic coatings through spin coating method. The coatings exhibited water contact angle greater than 90°. The properties of the hydrophobic coatings are analysed and characterized using scanning electron microscopy (SEM) and contact angle measurement (CA). The precursors are characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA) and gel permeation chromatography (GPC). These environment-friendly inorganic-organic hybrid coatings have shown great potential in replacing the toxic fluorinated alkylsilane based coatings.

Manipulating the interlayer carrier diffusion and extraction process in organic-inorganic heterojunctions: from 2D to 3D structures

Interlayer carrier transfer at heterointerfaces plays a critical role in light to electricity conversion using organic and nanostructured materials. However, how interlayer carrier extraction at these interfaces is poorly understood, especially in organic-inorganic heterogeneous systems. Here, we provide a direct strategy for manipulating the interlayer carrier diffusion process, transfer rate and extraction efficiency in tetracene/MoS2 type-II band alignment heterostructure by constructing the 2D–3D organic-inorganic (O-I) system. As a result, the prolonged diffusion length (12.32 nm), enhanced electron transfer rate (9.53 × 109 s−1) and improved carrier extraction efficiency (60.9%) are obtained in the 2D O-I structure which may be due to the more sufficient charge transfer (CT) state generation. In addition, we have demonstrated that the interlayer carrier transfer behavior complied with the diffusion mechanism based on the one-dimensional diffusion model. The diffusion coefficients have varied from 0.0027 to 0.0036 cm2 s−1 as the organic layer changes from 3D to 2D structures. Apart from the relationship between the carrier injection and diffusion process, temperature-dependent time-resolved spectra measurement is used to reveal the trap-related recombination that may limit the interlayer carrier extraction. The controllable interlayer carrier transfer behavior enables O-I heterojunction to be optimized for optoelectronic applications.

Highly transparent and resilient urethane-methacrylate siloxane composite for hard, yet stretchable protective coating

Although foldable electronic devices have been commercially available for some time now, flexible protective coating with sufficient reliability is yet to be achieved. The integration of polyurethane acrylate and an organic-inorganic (O-I) siloxane hybrid is proposed in this study as a promising protective coating, where both high strength and stretchability could be achieved to allow for the needed reliability for foldable electronics. In this work, a urethane-methacrylate siloxane hybrid (U-MSH) composite was fabricated by a physical blending of methacrylate-functionalized oligosiloxane and acrylate terminated urethane prepolymer followed by curing. The U-MSH composite demonstrates excellent performance in terms of optical (e.g., transmittance, Abbe number, UV stability) and mechanical properties (e.g., resilience under compression, tension, and scratch). These outstanding properties can be attributed to the synergetic effect of the combined polyurethane acrylate and O-I siloxane hybrid. Excellent reliability of U-MSH coating film is successfully demonstrated using an outward-bending test, suggesting that U-MSH has great potential as a protective material for flexible electronics.

Linear and nonlinear optical excitons in primary cyclic ammonium based inorganic–organic hybrid semiconductor series

The low dimensional inorganic–organic (IO) hybrid semiconductors become a fascinating subject of interest due to their unique crystal structural packing and tunable optical exciton emission features. These naturally self-assembled 2D IO hybrid semiconductors form multiple quantum wells (MQWs) like structure due to the quantum widths of both organic moiety and inorganic network , enabling them to show stable room temperature Mott-type excitons with large exciton binding energy. A systematic co-existence of two kinds of excitons observable from one-(ħω ≥ Eg) and two-photon (2ħω ≥ Eg) excitations is studied to probe into deeper details of sensitive structural changes in the IO-hybrids thin film and single crystals.

Structure-Dependent (Non)Linear Optical Excitons in Primary Cyclic Ammonium (CnH2n–1NH2; n = 3–8)-Based Inorganic–Organic Hybrid Semiconductor Series

This work reports the synthesis, structural, linear, and nonlinear optical investigations into low-dimensional naturally self-assembled inorganic–organic (IO) hybrid systems based on (CnH2n–1NH3)+ ...

Alternative fabrication methodologies for two-dimensional self-assembled Inorganic-Organic hybrid semiconductors

This report presents the structural and optical properties of(R-NH 3 ) 2 PbI 4 type Inorganic-Organic (IO) hybrids, prepared from alternative fabrication techniques, without any excess usage of Iodine. The fabrication relies on common deposition techniques viz., thermal vacuum deposition, electrochemical deposition, and spincoating. The resulting two-dimensional (2D) structures are alternatively stacked-up along c-axis by inorganic (PbI 6 extended network) layers with organic (R–NH 3 ) - moieties as spacers. These hybrids show strong room-temperature exciton features confined within the lowest inorganic bandgap. The proposed methodologies are simple alternatives to the conventional multi-step fabrication methodologies and are directly applicable to varieties of IO hybrids of different dimensionalities for various optoelectronic applications. • Novel methodologies for IO hybrids without metal halide and excess of halide usage. • Efficient direct conversion of pure Pb metal films into perfect layered 2D IO hybrids. • Nano and microcrystal fabrication from lead acetate based electrodeposition. • Strong room-temperature exciton photoluminescence from IO hybrids is demonstrated.

Organic-inorganic hybrid coatings containing phosphorus precursors prepared by sol–gel on Ti6Al4V alloy: Electrochemical and in-vitro biocompatibility evaluation

The durability and long-term success of metallic implants are enhanced through the molecular scale design of biocompatible and corrosion resistant surface coatings. To pursue this hypothesis, we have developed a new class of organic-inorganic (O-I) hybrid nanocomposite coatings based on tetramethylorthosilicate (TMOS) and γ-methacryloxypropyltrimethoxysilane (MAPTMS) as organofunctional alkoxysilanes precursors and dimethyltrimethylsilylphosphite (DMTMSP) as a phosphorus precursor. Addition of DMTMSP to TMOS-MAPTMS hybrids increased the extent of intermolecular condensation and cross-linking observed. Both normal human osteoblast in-vitro biocompatibility and corrosion resistance were enhanced in coatings containing DMTMSP. Though increasing phosphorous content correlated with biocompatibility, a compromise in the amount of phosphorus incorporated would be required if corrosion resistance was the most desirable parameter for optimization, at least for single coat systems. Evaluation of the electrochemical behaviour and the in-vitro biocompatibility show that films prepared using these materials by dip coating onto Ti6Al4V alloys offer a promising alternative to simpler coatings and wholly metallic prostheses.

Emission Control from Transition Metal Dichalcogenide Monolayers by Aggregation-Induced Molecular Rotors.

Organic-inorganic (O-I) heterostructures, consisting of atomically thin inorganic semiconductors and organic molecules, present synergistic and enhanced optoelectronic properties with a high tunability. Here, we develop a class of air-stable vertical O-I heterostructures comprising a monolayer of transition-metal dichalcogenides (TMDs), including WS2, WSe2, and MoSe2, on top of tetraphenylethylene (TPE) core-based aggregation-induced emission (AIE) molecular rotors. The created O-I heterostructures yields a photoluminescence (PL) enhancement of up to ∼950%, ∼500%, and ∼330% in the top monolayer WS2, MoSe2, and WSe2 as compared to PL in their pristine monolayers, respectively. The strong PL enhancement is mainly attributed to the efficient photogenerated carrier process in the AIE luminogens (courtesy of their restricted intermolecular motions in the solid state) and the charge-transfer process in the created type I O-I heterostructures. Moreover, we observe an improvement in photovoltaic properties of the TMDs in the heterostructures including the quasi-Fermi level splitting, minority carrier lifetime, and light absorption. This work presents an inspiring example of combining stable, highly luminescent AIE-based molecules, with rich photochemistry and versatile applications, with atomically thin inorganic semiconductors for multifunctional and efficient optoelectronic devices.

Conductive Organic Polymer Based Inorganic-Organic Hybrid Composite: Synthesis and Characterization

Inorganic organic (IO) hybrids where inserted conducting organic polymer (COP) imprints their polymeric nature onto the hybrid material are one of the most promising candidates for solving many technological problems of modern technocratic society. The Inorganic-organic hybrid material of para toluidine (organic) & mercuric chloride (inorganic) was synthesized by using “instant-heating and slow-cooling” technique. Some light orange coloured plate-like crystals were obtained. XRD pattern of the grown crystal were analysed which shows that crystal has been grown into monoclinic crystal system in which a ≠ b ≠ c [10.061(4) A ≠ 4.317(2) A ≠ 12.987(5) A] & α=γ= 90 o ≠ β [α = γ = 90 o , β=104.322(7) o ] and belongs to space group p2 1 .Analysis of secondary interactions shows that such material has potential application in opto electronics.

Facile growth and re-crystallization of polymer-based inorganic-organic 2D hybrid composites and their applications

The in-situ growth and recrystallization of inorganic-organic (IO) hybrids within the natural free volume of polymer matrices for the realization of significantly stable IO hybrid-polymer composites and its applications have been presented. A general strategy is explored to attain uniform and facile growth of IO hybrid nanocrystals (2–3 nm) within the interstitial spaces of polymer matrix. Annealing further supports the agglomeration and self-assembly of nanocrystals into highly c-oriented hexagonal microplatelets of ∼10–20 μm2 and 50–100 nm thickness within the polymer matrix. The resultant composites endow highly luminescent retaining the typical thermally and mechanically stable polymeric nature. Series of optical, structural, morphological and thermal studies are performed to understand the growth conditions and uniform distribution of IO nanocrystallites within the polymer. To exemplify, LED colour conversion using encapsulation/surface coating and polymeric blocks fabrication for optical waveguide/channel inscription are demonstrated to foresee many new flexible and robust applications. Thus, the present approach offers a new paradigm to achieve light-emitting IO hybrids in the form of polymeric composites for advanced optoelectronic device applications.

The Role of Nanoanalytics in the Development of Organic-Inorganic Nanohybrids-Seeing Nanomaterials as They Are.

The functional properties of organic-inorganic (O-I) hybrids can be easily tuned by combining system components and parameters, making this class of novel nanomaterials a crucial element in various application fields. Unfortunately, the manufacturing of organic-inorganic nanohybrids still suffers from mechanical instability and insufficient synthesis reproducibility. The control of the composition and structure of nanosurfaces themselves is a specific analytical challenge and plays an important role in the future reproducibility of hybrid nanomaterials surface properties and response. Therefore, appropriate and sufficient analytical methodologies and technical guidance for control of their synthesis, characterization and standardization of the final product quality at the nanoscale level should be established. In this review, we summarize and compare the analytical merit of the modern analytical methods, viz. Fourier transform infrared spectroscopy (FTIR), RAMAN spectroscopy, surface plasmon resonance (SPR) and several mass spectrometry (MS)-based techniques, that is, inductively coupled plasma mass spectrometry (ICP-MS), single particle ICP-MS (sp-ICP-MS), laser ablation coupled ICP-MS (LA-ICP-MS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), liquid chromatography mass spectrometry (LC-MS) utilized for characterization of O-I nanohybrids. Special attention is given to laser desorption ionization mass spectrometry (LDI-MS) as a reliable nanoanalytical platform for characterization of O-I hybrid nanomaterials, their quality, design verification and validation.

Synthesis, Structural, Linear, and Nonlinear Optical Studies of Inorganic–Organic Hybrid Semiconductors (R–C6H4CHCH3NH3)2PbI4, (R = CH3, Cl)

Synthesis, crystal structure, and optical properties of two-dimensional (2D) layered structurally slightly different inorganic–organic (IO) hybrid semiconductors (R–C6H4C2H4NH3)2PbI4 (R = CH3, Cl) are presented. They are naturally self-assembled systems where two (RNH3)+ moieties are sandwiched between two infinitely extended 2D layers of the [PbI6]4– octahedral network and treated as natural IO multiple quantum wells. While the former compound crystallizes into an orthorhombic system in the Cmc21 space group, the latter crystallizes into a monoclinic system in the space group P21/c. As a thin film, they are well-oriented along the (l00) direction. Both single crystals and thin films show strong room-temperature Mott type exciton features that are highly sensitive to the self-assembly and crystal packing. Linear (one-photon) and nonlinear (two-photon) optical probing of single crystals for exciton photoluminescence imaging and spectral spatial mapping provide deep insight into the layered re-arrangement and structural crumpling due to organic conformation. The strongly confined excitons, within the lowest band gap of inorganic, show distinctly different one- and two-photon excited photoluminescence peaks: free excitons from perfectly aligned 2D self-assembly and energy down-shifted excitons originated from the locally crumpled layered arrangement. Their structural aspects are successfully presented with proper correlation that emphasize various differences in physical and optical properties associated between these novel IO hybrids.

Surface Properties of Structure-Controlled Silica Films Prepared Using Organic-Inorganic Hybrid Solutions

Silica films with various microstructures were fabricated using organic-inorganic (O-I) hybrid solutions containing a mixture of silica sols, polymethylmethacrylate (PMMA), and urethane acrylate nonionomer (UAN) as an amphiphilic polymer, The O-I hybrid solutions were prepared with various UAN:PMMA and polymer/solvent ratios, then spin-coated on glass and calcinated at 450 °C to produce silica films with various microphase-separated structures. For higher UAN and PMMA concentrations, the silica films showed spherical inorganic domains dispersed over the surface, while many pores were formed in the films with lower polymer contents (observed using scanning electron microscopy). The surface hydrophobicity of the silica films was determined using water contact angle measurements. After surface modification using (1H, 1H, 2H, 2H-perfluorooctyl)trichlorosilane solution, the hydrophobicity of films with a highly microphase-separated structure increased significantly, and all surface-modified films showed increasing hydrophobicity with increasing polymer content. Furthermore, pencil scratch hardness tests showed that the silica films formed on glass substrates could withstand the 5H scratch, test even after surface modification.

Quantum Confinement of Hybrid Charge Transfer Excitons in GaN/InGaN/Organic Semiconductor Quantum Wells.

We investigate hybrid charge transfer exciton (HCTE) confinement in organic-inorganic (OI) quantum wells (QWs) comprising a thin InGaN layer bound on one side by GaN and on the other by the organic semiconductors, tetraphenyldibenzoperiflanthene (DBP) or 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP). A binding energy of 10 meV is calculated for the Coulombically bound free HCTE state between a delocalized electron in GaN and a hole localized in DBP. The binding energy of the HCTE increases to 165 meV when the electron is confined to a 1.5 nm In0.21Ga0.79N QW (HCTEQW). The existence of the HCTEQW is confirmed by measuring the voltage-dependent DBP exciton dissociation yield at the OI heterojunction in the QW devices that decrease with increasing In concentration and decreasing electric field, matching the trends predicted by Poole-Frenkel emission. Combining spectroscopic measurements with optical models, we find that 14 ± 3% of the excitons that reach the GaN/DBP heterojunction form HCTEs and dissociate into free charges, while the remainder recombine. A high nonradiative recombination rate through defect states at the heterointerface account for the lack of observation of HCTEQW photoluminescence from GaN/InGaN/CBP QWs at temperatures as low as 10 K.

Silicon‐Based Inorganic–Organic Hybrid Nanocomposites for Optoelectronic Applications

AbstractA nanocomposite consisting of a unique combination of optically active materials, that is, an inorganic–organic (IO) layered hybrid and porous silicon (PS), is prepared using a simple but effective three‐step electrochemical method. X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, and photoluminescence spectral analysis suggest that the IO hybrid (R‐MX4‐type 2D perovskite, where R represents an organic compound, M a divalent metal ion, and X a halide) is conveniently incorporated into the interstitial spaces of nanoporous silicon. The IO‐based 2D perovskite emits a strong and narrow room‐temperature exciton line at 520 nm due to effects related to dielectric confinement. Similarly, n‐type porous silicon emits in a broad range in the deep‐red region at 700 nm, which is attributable to the quantum confinement effects related to the nanoporosity in silicon. Because of the contributions from both entities, the completely space‐filled IO–PS nanocomposite shows an orange–yellow emission. The proposed methodology can be easily extended to a large number of such IO–PS functional nanocomposites and is thus expected to be used in optoelectronic applications such as light‐emitting diodes (LEDs), solar cells, and other optical elements.