Inorganic Layers Research Articles

Enabling All‐Solid‐State Li Metal Batteries Operated at 30 °C by Molecular Regulation of Polymer Electrolyte

AbstractThe low ionic conductivity of poly(ethylene oxide) (PEO)‐based polymer electrolytes at room temperature and the undesired lithium‐dendrite growth at Li|PEO interface impede their further application. Herein, a PEO polymer is regulated at the molecular level through a copper ion (Cu2+) coordination effect with both PEO and Li salts to achieve a high Li+ conductivity of 0.2 mS cm−1 and a transference number of 0.42 at 30 °C. Moreover, the Cu‐coordinated PEO electrolyte is neither sticky nor hygroscopic because the hydrophilic oxygen groups in PEO are terminated by Cu ions. Furthermore, the in situ formed F/Li‐rich inorganic layer induced by CuF2 additive accelerates Li+ transport kinetics and enables uniform Li+ deposition during Li plating/stripping. As a result, the Cu2+‐coordinated PEO electrolytes deliver a high critical current density of 1.5 mA cm−2 at 30 °C. An all‐solid‐state Li‐LiNi0.83Co0.12Mn0.05O2 (NCM83) battery with such a copper coordinated PEO electrolyte exhibits a long cycle life over 500 cycles with a capacity retention of 71% under 0.6 C at 30 °C. When the mass loading increases to a record high of 7 mg cm−2, the Li‐NCM83 cell delivers a high areal capacity of 1.07 mAh cm−2 under 0.1 C at 30 °C.

Mechanical Stability of the Heterogenous Bilayer Solid Electrolyte Interphase in the Electrodes of Lithium–Ion Batteries

Mechanical stability of the solid electrolyte interphase (SEI) is crucial to mitigate the capacity fade of lithium–ion batteries because the rupture of the SEI layer results in further consumption of lithium ions in newly generated SEI layers. The SEI is known as a heterogeneous bilayer and consists of an inner inorganic layer connecting the particle and an outer organic layer facing the electrolyte. The growth of the bilayer SEI over cycles alters the stress generation and failure possibility of both the organic and inorganic layers. To investigate the probability of mechanical failure of the bilayer SEI, we developed the electrochemical-mechanical coupled model with the core–double-shell particle/SEI layer model. The growth of the bilayer SEI is considered over cycles. Our results show that during charging, the stress of the particle changes from tensile to compressive as the thickness of bilayer SEI increases. On the other hand, in the SEI layers, large compressive radial and tensile tangential stress are generated. During discharging, the compressive radial stress of the bilayer SEI transforms into tensile radial stress. The tensile tangential and radial stresses are responsible for the fracture and debonding of the bilayer SEI, respectively. As the thickness ratio of the inorganic to organic layers increases, the fracture probability of the inorganic layer increases, while that of the organic layer decreases. However, the debonding probability of both layers is decreased. In addition, the SEI covering large particles is more vulnerable to fracture, while that covering small particles is more susceptible to debonding. Therefore, tailoring the thickness ratio of the inorganic to organic layers and particle size is important to reduce the fracture and debonding of the heterogeneous bilayer SEI.

Solution-Processed Organic–Inorganic Semiconductor Heterostructures for Advanced Hybrid Phototransistors

Organic/inorganic hybrid phototransistors are an emerging class of advanced optoelectronic devices. The separated organic high absorption layer and inorganic carrier transport layer endow hybrid phototransistors with remarkable sensing performance in a broad spectrum. The flexibility, ambient stability, and process compatibility of organic and metal oxide semiconductors also render them promising for large-area matrix integration and wearable applications. Moreover, extraordinary photoelectric behaviors, such as bidirectional photoresponses and the versatility of in-sensor computing functions, including feature extraction and image enhancement, can be obtained by rational customization of the hybrid heterojunctions. In this Spotlight on Applications, we review the recent progress of organic/inorganic hybrid phototransistors and their applications in photodetection, sensor arrays, flexible electronics, and in-sensor computing.

Cs2AgBiBr6-based perovskite solar cell: A novel combination of ITO/CdS/ Cs2AgBiBr6/ CuAlO2/Pt, with inorganic charge transport layers

Cs2AgBiBr6 is a lead-free double halide perovskite, which has attracted attention as a potential replacement to toxic and unstable organic-inorganic perovskites due to its high structural stability, non-toxicity, and unique photoelectric properties. This work presents a Numerical analysis of a lead-free Cs2AgBiBr6-based perovskite solar via SCAPS software. The effect of several input parameters has been analyzed; after selecting the best Holes Transport Layer (HTL) and the best Electrons Transport Layer (ETL), we have optimized their thicknesses as well as their doping densities, we have also analyzed the impact of: the absorber thickness, its defect density (Nt), defect density at ETL/Cs2AgBiBr6 and Cs2AgBiBr6/HTL interfaces, ETL electron affinity, and front/back contact work function on device performance. Finally we obtained a solar device based on Cs2AgBiBr6with a fully inorganic structure. The results show that Cs2AgBiBr6 can play an important role as an absorbing perovskite in the development of solar cell technology.

Oriented adsorption and efficient sensing of NO2 on MoSe2 monolayer: a comparative study with WSe2 monolayer

Oriented adsorption is very rare on two-dimensional inorganic thin layers. Based on preliminary study, density functional theory (DFT) was used to explore the adsorption and sensing behavior of NO2 on MoSe2 perfect and defective monolayers including selenium vacancy (VSe), molybdenum vacancy (VMo), and antisite defect of selenium on molybdenum site (SeMo) by large-scale sampling. The adsorption energy can reach 0.29 eV with 0.182 e charge transfer on the perfect monolayer. The adsorption ability is improved largely on VSe, VMo, and SeMo monolayers (3.27, 0.93, and 1.20 eV) with considerable charge transfer (0.583, 0.152, and 0.139 e, respectively), demonstrating the potential of MoSe2 monolayers as NO2 sensing materials. Meanwhile, similar to WSe2 monolayer, oriented adsorption of NO2 is disclosed. NO2 molecule extends mainly along the Se–Mo–Se trough and the Se–Mo bond on all the four MoSe2 monolayers. Whereas, the oriented adsorption ability is weaker than the WSe2 monolayer, which can be confirmed by the relatively small proportion of oriented adsorption conformations. This kind of double oriented adsorption behavior (vertical adsorption and adsorption along specific direction of the two-dimensional material) was considered to be due to the good polarity match between molecule and monolayer. Molecular dipole moment and material bond population are believed to be two important parameters that determine the oriented adsorption capacity of molecular-material systems. The successive discovery of the unique oriented adsorption and the deepening of understanding provide chance for molecular design of oriented adsorption of inorganic small molecules on two-dimensional layered materials. The strong dissociation ability of the anionic vacancy monolayer to NO2 molecule indicates that MoSe2 monolayer has a very high adsorption, capture, and activation potential for nitrogen oxides. Comparative study proved that the Mo site activity was less than the W site activity on the perfect monolayer, and defects could help the Mo site activity overtake. These findings provide pivotal guidance for creating advanced surface regulated electronic systems, such as sensors.

Photoluminescence and scintillation properties of organic-inorganic layered perovskite-type compounds (FC6H4C2H4NH3)2PbCl4 crystals

(C6H5C2H4NH3)2PbCl4 and (n-FC6H4C2H4NH3)2PbCl4 (n = 2, 3, and 4) crystals were grown by the slow-cooling method, and the optical and scintillation properties were investigated. From the X-ray diffraction pattern, F-substitution in a benzene ring makes the lattice constant larger than (C6H5C2H4NH3)2PbCl4. They exhibited photoluminescence and scintillation peaks due to the recombination of the self-trapped excitons confined in inorganic layers at 400–700 nm. The afterglow levels at 20 ms after X-ray irradiation for 2 ms were 100–600 ppm. From the pulse height spectra under 241Am α-ray (5.5 MeV) irradiation, the light yields of (C6H5C2H4NH3)2PbCl4, (3-FC6H4C2H4NH3)2PbCl4, and (4-FC6H4C2H4NH3)2PbCl4 samples were calculated to be 1,400, 1,800, and 1,700 ph/5.5 MeV-α.

In situ construction of a stable composite solid electrolyte interphase for dendrite-free Zn batteries

Building a stable solid electrolyte interphase (SEI) has been regarded to be highly effective for mitigating the dendrite growth and parasitic side reactions of Zn anodes. Herein, a robust inorganic composite SEI layer is in situ constructed by introducing an organic cysteine additive to achieve long lifetime Zn metal batteries. The chemisorbed cysteine derivatives are electrochemically reduced to trigger a local alkaline environment for generating a gradient layered zinc hydroxide based multicomponent interphase. Such a unique interphase is of significant advantage as a corrosion inhibitor and Zn2+ modulator to enable reversible plating/stripping chemistry with a reduced desolvation energy barrier. Accordingly, the cells with a thin glass fiber separator (260 μm) deliver a prolonged lifespan beyond 2000 h and enhanced Coulombic efficiency of 99.5% over 450 cycles. This work will rationally elaborate in situ construction of a desirable SEI by implanting reductive additives for dendrite-free Zn anodes.

Vapor Phase Infiltration Improves Thermal Stability of Organic Layers in Perovskite Solar Cells

Despite the rapid increase in power conversion efficiency (PCE) of perovskite solar cells (PSCs) over the past decade, stability remains a major roadblock to commercialization. This work shows vapor phase infiltration (VPI) as a tool to create hybrid organic–inorganic layers that improve the stability of organic charge transport layers, such as hole-selective spiro-OMeTAD in PSCs and in other organic electronic devices. Using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and grazing incident wide-angle X-ray scattering (GIWAXS), we identify that infiltration of TiOx via VPI hinders the crystallization of the spiro-OMeTAD layer by likely preventing the π–π stacking of the molecules. Infiltrated PSCs retained more than 80% of their original efficiency after an operando stability test of 200 h at 75 °C, double the efficiency retained by devices without infiltration, in which the efficiency rapidly decreases in the first 50 h. This work provides a blueprint for using VPI to stabilize organic charge transport layers via prevention of π–π stacking leading to deleterious crystallization that shortens device lifetimes.

Structural study, spectroscopic characterization, DFT calculations and electrical properties of manganese (II) organic-inorganic hybrid material (C8H14N2)2[MnCl4(H2O)2]Cl2

The new organic-inorganic compound, (C8H14N2)2[MnCl4(H2O)2]Cl2 denoted (1), crystallizes at room temperature in the monoclinic system, P21/c space group. The structure exhibits an alternate organic-inorganic layered stacking along a-axis. The inorganic layers formed by [MnCl4(H2O)2]2− anion and two uncoordinated chlorine anions. The organic layers are made of protonated m-Xylylenediamine (C8H14N2)2+. Crystal cohesion is achieved through NH…Cl and OH…Cl hydrogen bonds building up a three-dimensional network. The functional groups present in the crystal were studied by FTIR. The optical proprieties were investigated by UV-visible spectroscopy study and the electronic properties HOMO and LUMO energies were calculated by TD-DFT. Thermal behavior (DSC, DTA/TGA) was also performed, while the composition of the phase was verified by semi-quantitative analysis (EDX). Hirshfeld surface (3D-HS) analysis and the two-dimensional fingerprint plots (2D-FP) affirms that the structure is dominated by H…Cl/Cl…H and H…H contacts. Electrical analysis of our compound has been investigated using complex impedance spectroscopy (CIS) in frequency and temperature range 3 uHz-20 MHz and 393–443 K, respectively. Impedance spectroscopy studies show that electrical-conductivity is 1.80 10−6 S cm−1 at 443 K and the activation energy is 2.15 eV.

Photogenerated charge transfer in Dion-Jacobson type layered perovskite based on naphthalene diimide.

Incorporating organic semiconducting spacer cations into layered lead halide perovskite structures provides a powerful approach to mitigate the typical strong dielectric and quantum confinement effects by inducing charge-transfer between the organic and inorganic layers. Herein we report the synthesis and characterization of thin films of novel DJ-phase organic-inorganic layered perovskite semiconductors using a naphthalene diimide (NDI) based divalent spacer cation, which is shown to accept photogenerated electrons from the inorganic layer. With alkyl chain lengths of 6 carbons, an NDI-based thin film exhibited electron mobility (based on space charge-limited current for quasi-layered 〈n〉 = 5 material) was found to be as high as 0.03 cm2 V-1 s-1 with no observable trap-filling region suggesting trap passivation by the NDI spacer cation.

Pressure-induced distinct excitonic properties of 2D perovskites with isomeric organic molecules for spacer cations.

Spacer organic cations in two-dimensional (2D) perovskites play vital roles in inducing structural distortion of the inorganic components and dominating unique excitonic properties. However, there is still little understanding of spacer organic cations with identical chemical formulas, and different configurations have an impact on the excitonic dynamics. Herein, we investigate and compare the evolution of the structural and photoluminescence (PL) properties of [CH3(CH2)4NH3]2PbI4 ((PA)2PbI4) and [(CH3)2CH(CH2)2NH3]2PbI4 ((PNA)2PbI4) with isomeric organic molecules for spacer cations by combining steady-state absorption, PL, Raman and time-resolved PL spectra under high pressures. Intriguingly, the band gap is continuously tuned under pressure and decreased to 1.6 eV at 12.5 GPa for (PA)2PbI4 2D perovskites. Simultaneously, multiple phase transitions occur and the carrier lifetimes are prolonged. In contrast, the PL intensity of (PNA)2PbI4 2D perovskites exhibits an almost 15-fold enhancement at 1.3 GPa and an ultrabroad spectral range of up to 300 nm in the visible region at 7.48 GPa. These results indicate that the isomeric organic cations (PA+ and PNA+) with different configurations significantly mediate distinct excitonic behaviors due to different resilience to high pressures and reveal a novel interaction mechanism between organic spacer cations and inorganic layers under compression. Our findings not only shed light on the vital roles of isomeric organic molecules as organic spacer cations in 2D perovskites under pressure, but also open a route to rationally design highly efficient 2D perovskites incorporating such spacer organic molecules in optoelectronic devices.

Energy level alignments between organic and inorganic layers in 2D layered perovskites: conjugation vs. substituent.

2D layered hybrid perovskites have attracted huge attention due to their interesting optoelectronic properties and chemical flexibility. Depending upon their electronic structures and properties, these materials can be utilised in various optoelectronic devices like photovoltaics, LEDs and so on. In this context, study of the excited energy levels of the organic spacers can help us to align the excited energy levels of the organic unit with the excitonic level of the inorganic unit according to the requirement of a particular optoelectronic device. We have explored the role of 3-phenyl-2-propenammonium on the electronic structure of a perovskite containing this cation as a spacer. Our results clearly demonstrate the active participation of conjugated ammonium spacers in the electronic structure of a perovskite. Also, we have considered a variety of amines to identify the best alignment with common inorganic units and studied the role of substituents and conjugation on the energy level alignment. Placing the triplet excited level of an organic spacer below the lowest excitonic level of the inorganic unit can induce energy transfer from the inorganic to organic unit, finally resulting in phosphorescence emission. We have shown that the triplet energy level of 3-anthracene-2-propeneamine/3-pyrene-2-propeneamine can be tuned in such a way that there can be an excitonic energy transfer from the Pb2I7/PbI4 inorganic unit-based perovskites. Therefore, perovskite material with such combinations of organic spacer cations will be very useful for light emission applications.

Achieving above 24% efficiency with non-toxic CsSnI3 perovskite solar cells by harnessing the potential of the absorber and charge transport layers.

Lead toxicity is a barrier to the widespread commercial manufacture of lead halide perovskites and their use in solar photovoltaic (PV) devices. Eco-friendly lead-free perovskite solar cells (PSCs) have been developed using certain unique non- or low-toxic perovskite materials. In this context, Sn-based perovskites have been identified as promising substitutes for Pb-based perovskites due to their similar characteristics. However, Sn-based perovskites suffer from chemical instability, which affects their performance in PSCs. This study employs theoretical simulations to identify ways to improve the efficiency of Sn-based PSCs. The simulations were conducted using the SCAPS-1D software, and a lead-free, non-toxic, and inorganic perovskite absorber layer (PAL), i.e. CsSnI3 was used in the PSC design. The properties of the hole transport layer (HTL) and electron transport layer (ETL) were tuned to optimize the performance of the device. Apart from this, seven different combinations of HTLs were studied, and the best-performing combination was found to be ITO/PCBM/CsSnI3/CFTS/Se, which achieved a power conversion efficiency (PCE) of 24.73%, an open-circuit voltage (VOC) of 0.872 V, a short-circuit current density (JSC) of 33.99 mA cm-2 and a fill factor (FF) of 83.46%. The second highest PCE of 18.41% was achieved by the ITO/PCBM/CsSnI3/CuSCN/Se structure. In addition to optimizing the structure of the PSC, this study also analyzes the current density-voltage (J-V) along with quantum efficiency (QE), as well as the impact of series resistance, shunt resistance, and working temperature, on PV performance. The results demonstrate the potential of the optimized structure identified in this study to enhance the standard PCE of PSCs. Overall, this study provides important insights into the development of lead-free absorber materials and highlights the potential of using CsSnI3 as the PAL in PSCs. The optimized structure identified in this study can be used as a base for further research to improve the efficiency of Sn-based PSCs.

Chemical bottom-up approach for inorganic single-atomic layers aiming beyond graphene.

A chemical bottom-up approach for single-atomic-layered materials like graphene is attractive due to the possibility of introducing functions. This article includes the synthesis and properties of borophene-oxide and metalladithiolene layers, which are reported as inorganic materials. They have graphene-like two-dimensional networks that enable conjugated structures. Their atomically thin layers are also available by dissolution or synthetic methods. Their two-dimensional electronic features are evaluated from the activation energies for electrical conduction, focusing on the anisotropic features of borophene-oxide layers and the switching abilities of metalladithiolene layers.

Vapor Deposition of All Inorganic Perovskite Transport Layer and Emission Layer to Improve Performance of Red Perovskite Light-emitting Diodes

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An Fe3O4 based hole transport bilayer for efficient and stable perovskite solar cells

Insertion of a thin inorganic Fe3O4 layer between perovskite and spiro-OMeTAD improves charge extraction and device efficiency and also boosts device shelf-life stability.

A new series of magnetic and luminescent layered hybrid materials obtained from thianthrene phosphonic acid: M(H2O)PO3-S2C12H7 (M = Cu, Zn) and M(H2O)2(PO2OH-S2C12H7)2 (M = Mn, Co).

Four new metallophosphonates with the chemical formulae M(H2O)PO3-S2C12H7 (M = Cu, Zn) and M(H2O)2(PO2OH-S2C12H7)2 (M = Mn, Co) were synthesized using a hydrothermal route from the original bent rigid thianthrene-2-ylphosphonic acid (TPA). This organic precursor crystallizes in a non-centrosymmetric space group P212121 and presents a unique bent geometry due to the presence of two sulfur atoms in its rigid platform architecture. Obtained as single crystal and polycrystalline powders, the structures of the four hybrid materials were solved using X-ray diffraction on single crystals in a monoclinic P21/c space group. These compounds adopt a lamellar structure consisting of one inorganic subnetwork alternating with a 'sawtooth' double organic -S2C12H7 subnetwork. The inorganic layers of these compounds are made of (PO3C) or partially deprotonated (PO2OHC) tetrahedra connected by the apices to isolated ZnO3(H2O) tetrahedra, Cu2O6(H2O)2 copper dimers and cobalt and manganese MO4(H2O)2 octahedra, where the latter two exhibit an isotype structure. Thermogravimetric analysis was performed to confirm the amount of water molecules present in the formula, to track the dehydration process of the structures, and to evaluate their thermal stability. The magnetic properties of the copper, cobalt, and manganese-based materials were investigated from 2 K to 300 K by using a SQUID magnetometer revealing dominant antiferromagnetic interactions with Weiss temperatures of -8.0, -10, and -1 K, respectively. These magnetic behaviors were further corroborated by first-principles simulations based on Density Functional Theory (DFT). Finally, the absorption and photoluminescence properties of both the ligand and hybrid materials were investigated, revealing diverse excitation and recombination mechanisms. The organic moiety based on thianthrene significantly influenced the absorption and emission, with additional peaks attributed to transition metals. Singlet and triplet states recombination were observed, accompanied by an unidentified quenching mechanism affecting the triplet state lifetime.

Role of inorganic layers on polysulfide decomposition at sodium-metal anode surfaces for room temperature Na/S batteries.

Sodium metal is a promising anode material for room-temperature sodium sulfur batteries. Due to its high reactivity, typical liquid electrolytes (e.g. carbonate-based solvents and a Na salt) can undergo reduction to form a solid electrolyte interphase (SEI) layer, with inorganic components such as Na2CO3, Na2O, and NaOH, covering the anode surface along with other SEI organic products. One of the challenges is to understand the effect of the SEI film on the decomposition of soluble sodium polysulfide molecules (e.g., Na2S8) upon shuttling from the cathode to anode during battery cycling. Here, we use ab initio molecular dynamics (AIMD) simulations to study the role of an inorganic SEI used as a model passivation layer in polysulfide decomposition. Compared to other film chemistries, it is found that the Na2CO3 film can suppress decomposition with the slowest reduction rate and the smallest amount of charge transfer towards Na2S8. The Na2CO3 film can maintain its structural properties during the simulations. In contrast, Na2O and NaOH allow some decomposed polysulfide fragments to be inserted into the SEI layer. Moreover, the decomposition of Na2S8 on both Na2O and NaOH SEI layers is more reactive with more charge transfer to Na2S8 when compared to that of Na2CO3. Thus, the ability of the SEI to suppress polysulfide decomposition is in the order: Na2CO3 > NaOH ∼ Na2O. Analyses of the density of states reveal that the Na2S8 molecule receives electrons from the Na metal directly in the presence of n-type semiconductor films of Na2CO3 and NaOH, while the charge migration behavior is different in a p-type semiconductor Na2O with the SEI film donating its electrons to the polysulfide solely. Thus, this work adds new insights into charge transfer behavior of inorganic thin film SEIs that could be present at the initial stages of SEI formation.

Regulating structural asymmetry via fluorination engineering in hybrid lead bromide perovskites.

Here, we synthesized a pair of chiral two-dimensional lead bromide perovskites R-/S-(C3H7NF3)2PbBr4 (1R/2S) using a H/F substitution strategy, which exhibit circular dichroism (CD) and circularly polarized luminescence (CPL) activity. Compared with one-dimensional non-centrosymmetric (C3H10N)3PbBr5 with local asymmetry obtained by isopropylamine, 1R/2S show a centrosymmetric inorganic layer despite the global chiral space group. Density functional theory calculations show that the formation energy of 1R/2S is lower than that of (C3H10N)3PbBr5, which implies the improved moisture stability in photophysical properties and CPL activity.

Incorporation of Conjugated Diynes in Perovskites and their Post-Synthetic Modification.

Two-dimensional (2D) organic-inorganic hybrid perovskites have rapidly become an attractive alternative to three-dimensional (3D) perovskites as solar cell absorbers, owing to their improved stability, versatility, and ease of processing. Despite their advantages, the insulating nature of the organic cations makes these materials have lower absorbing and conducting properties, resulting in lower device efficiencies. A way to circumvent these issues is the integration of functional molecules that help mitigate these limitations. In this study, six new perovskites composed of three distinct diynes are synthesized, all of which can be thermally polymerized to form conjugated polymers within the perovskite layers. The incorporation of conjugated polymers results in drastic changes in these materials' optoelectronic properties and their overall stability. Furthermore, depending on the nature of the diyne and the inorganic layers, the materials show varying polymerization yields, optical bandgaps, and charge carrier densities. These results afford significant insight into the chemical nature of the polymerized species and thus highlight the versatility of this approach to post-synthetically generate conducting polymers within the layers of 2D perovskites, paving the way toward their use in optoelectronic devices.