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Two‐dimensional organic–inorganic hybrid perovskites (OIHPs) with alternating structure of the organic and inorganic layers have a natural quantum well structure. The difference of dielectric constants between organic and inorganic layers in this structure results in the enhancement of dielectric confinement effect, which exhibits a large exciton binding energy and hinders the separation of electron‐hole pairs. Herein, a strategy to reduce the dielectric confinement effect by narrowing the dielectric difference between organic amine molecule and [PbBr6]4− octahedron is put forward. The Ethanolamine (EOA) contains hydroxyl groups, resulting in the positive and negative charge centers of O and H non‐overlapping, which generated a larger polarity and dielectric constant. The reduced dielectric constant produces a smaller exciton binding energy (71.03 meV) of (C2H7NO)2PbBr4 ((EOA)2PbBr4) than (C8H11N)2PbBr4 ((PEA)2PbBr4 (156.07 meV), and promotes the dissociation of electrons and holes. The increasing of lifetime of photogenerated carrier in (EOA)2PbBr4 are proved by femtosecond transient absorption spectra. Density functional theory (DFT) calculations have also indicated that the small energy shift of the total density of states (DOS) between the C/H/N and the Pb/Br in (EOA)2PbBr4 favors the separation of electrons and holes. In addition, this work demonstrates the application of (PEA)2PbBr4 and (EOA)2PbBr4 in the field of photocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid perovskites like methylammonium lead iodide (MAPbI3) have received extensive attention in solar energy conversion due to their superb optoelectronic properties. However, the serious charge recombination at the nanoscale domain and the lack of catalytic sites on the perovskite's surface seriously limit their photocatalytic hydrogen evolution activities. Taking MAPbI3 as a typical example, we show that coupling amorphous molybdenum phosphide (MoP) cocatalyst with MAPbI3 can significantly enhance the photocatalytic H2 evolution performance of MAPbI3. The MoP coupling can accelerate the electron extraction from MAPbI3 and promote the hydrogen evolution reaction catalysis. Consequently, the photocatalytic hydrogen evolution activity of MoP/MAPbI3 is ca. 97 times higher than that of bare MAPbI3. Moreover, the MoP/MAPbI3 exhibits good stability during cycling tests. This work demonstrates the possibility of employing amorphous MoP as a non-noble metal-based cocatalyst in a hybrid perovskite-based photocatalytic hydrogen production reaction. Methylammonium lead iodide (MAPbI3) loaded with molybdenum phosphide (MoP) cocatalyst demonstrates 97 times higher photocatalytic hydrogen evolution activity than bare MAPbI3 from HI splitting reaction under visible light irradiation. [ABSTRACT FROM AUTHOR]

As an important photovoltaic material, organic–inorganic hybrid perovskites have attracted much attention in the field of solar cells, but their instability is one of the main challenges limiting their commercial application. However, the search for stable perovskites among the thousands of perovskite materials still faces great challenges. In this work, the energy above the convex hull values of organic–inorganic hybrid perovskites was predicted based on four different machine learning algorithms, namely random forest regression (RFR), support vector machine regression (SVR), XGBoost regression, and LightGBM regression, to study the thermodynamic phase stability of organic–inorganic hybrid perovskites. The results show that the LightGBM algorithm has a low prediction error and can effectively capture the key features related to the thermodynamic phase stability of organic–inorganic hybrid perovskites. Meanwhile, the Shapley Additive Explanation (SHAP) method was used to analyze the prediction results based on the LightGBM algorithm. The third ionization energy of the B element is the most critical feature related to the thermodynamic phase stability, and the second key feature is the electron affinity of ions at the X site, which are significantly negatively correlated with the predicted values of energy above the convex hull (Ehull). In the screening of organic–inorganic perovskites with high stability, the third ionization energy of the B element and the electron affinity of ions at the X site is a worthy priority. The results of this study can help us to understand the correlation between the thermodynamic phase stability of organic–inorganic hybrid perovskites and the key features, which can assist with the rapid discovery of highly stable perovskite materials. [ABSTRACT FROM AUTHOR]

Organic-inorganic methylammonium lead iodide perovskite (MAPbI3) nanowires (NWs) have attracted significant attention in the realm of optoelectronic devices due to their outstanding optoelectronic properties. However, the persistent challenge of high trap densities has been a limiting factor in realizing their full potential in device performance. To address this challenge, we incorporated cesium (Cs) and systematically investigated the impact of Cs concentration on the trap densities and the optoelectronic characteristics of Cs x MA(1− x)PbI3 NWs. Our findings unveiled an initial reduction in trap densities as Cs+ content increased, with the lowest point occurring at x = 0.2. However, beyond this threshold, trap densities began to rise, eventually surpassing those observed in pure MAPbI3 at x = 0.4. Furthermore, we fabricated single NW photodetectors to assess how Cs+ content influenced optoelectronic properties. The results indicated that Cs+ incorporation led to enhancements in photocurrent and response speed, withthe optimal performance observed at x = 0.2. Our study provides valuable insights into the role of Cs+ incorporation in tailoring the optoelectronic properties of perovskite NWs. [ABSTRACT FROM AUTHOR]

The importance of the phonon bottleneck effect on the optoelectronic properties of organic-inorganic hybrid perovskites (OIHPs) has been well documented. While randomly distributed multiple quantum wells (MQWs) are frequently generated in 2D/3D perovskite heterostructures, the influence of MQWs formation in 2D/3D perovskite heterostructures on the phonon bottleneck effect is poorly understood. In this study, we construct 2D/3D perovskite heterostructures using 2D OIHP (NH3(CH2)8NH3PbI4, OdAPbI4) to passivate 3D OIHP (FAPbI3) and investigate their excitons and carrier dynamics by employing photoluminescence (PL) spectroscopy and femtosecond optical-pump terahertz-probe spectroscopy (fsOPTPS). We observe the formation of MQWs and establish a structure-dynamics-property relationship among the exciton formation time (TEF), the hot carrier cooling rate (kcool) and the effective charge-carrier mobility(ϕμ). The formation of MQWs could significantly invalidate the phonon bottleneck effect and modulate the optoelectronic properties of 2D/3D perovskite heterostructures. This work provides valuable information on the importance of band alignment and the phonon bottleneck effect in the strategy of 2D/3D perovskite heterostructures. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) organic–inorganic hybrid perovskites (OIHPs) have drawn increased attention due to rich physical properties such as ferroelectricity and photovoltaic properties. Nevertheless, it is challenging to discover novel 2D OIHPs within the vast chemical composition space. Herein, a diagrammatic machine learning model was employed to improve this issue. We collected 179 OIHPs with a variety of organic cations and screened out 6 features from 10,622 descriptors. Subsequently, a decision tree model was created to predict the dimensionality of OIHPs, achieving a LOOCV accuracy of 0.94 and a test accuracy of 0.89, respectively. Then, one candidate from a virtual space with 8256 samples was successfully synthesized, which was consistent with the prediction of the model. Finally, three rules were produced by visualization of the tree structure to generally discriminate 2D from non-2D OIHPs. It is believed that the diagrammatic model has reliability in identifying 2D OIHPs and will serve further property studies of OIHPs in the future.

Organic‐inorganic hybrid perovskite (MAPbX3) is known having excellent photoelectric properties. Compared to polycrystalline films, perovskite micro/nanowires can provide improved optoelectronic properties, mechanical flexibility, and adaptability due to higher crystallinity. However, their economical, scalable, and controllable fabrication remains a challenge. In this work, the authors report a facile way to fabricate high‐quality MAPbX3 triangular‐micro‐wires (TMWs). The Si/SiO2 substrate with triangular‐micro‐trenches (TMTs) array serves as the template for the growth of MAPbX3 TMWs array through blade coating. The MAPbX3 TMW first nucleated at the trench bottom, which facilitating the nanowire growth with high crystallinity. In addition, the size and periodicity of TMTs array can be independently controlled, providing potential for scale‐up device applications. The photodetectors fabricated with these MAPbI3 TMWs show excellent responsivity of (144.5 ± 2.1) A/W and specific detectivity of (2.7 ± 0.02) × 1011 Jones under weak light (0.5 µW cm−2). Their photoresponse to pulsed light is stable and reproducible, with rise and decay times of 7.5 and 6.0 ms, respectively. Finally, with the demonstration of the image sensor application, MAPbX3 TMWs array is anticipated to be suitable for large‐area, high‐performance integrated optoelectronics. [ABSTRACT FROM AUTHOR]

The design and fabrication of a flexible electric‐optical perovskite/electrolyte synaptic transistor are demonstrated for the first time, which emulates important neuromorphic functions under dual‐mode modulation. Benefiting from the bipolar charge transport properties of light‐harvesting perovskite and the high specific capacitance and mechanically robust multi‐ion electrolyte, the device exhibits bidirectional plasticity, better reliability, retaining >70% of the initial current level after 2500 flex per flat laps, and a very wide operating voltage window from 0.04 to 10 V, and responsive to ultralow stimuli down to tens of millivolt level with femtojoule‐level energy consumption. The synergistic high response under dual‐mode modulation enables the device to emulate complex neural learning rules and achieve neuromorphic applications, including classical conditioning and spatiotemporal learning, and image recognition tasks with higher accuracy of 81%. Moreover, an enhanced artificial reflex‐arc behavior is emulated by employing the flexible electro‐optical artificial synapses that serve as key information‐receiving‐processing units to manipulate the actions of electrochemical artificial muscles to a larger extent. These properties show great potential in soft neurorobotic systems and prostheses. [ABSTRACT FROM AUTHOR]

Cl, Br, and I are elements in the halogen family, and are often used as dopants in semiconductors. When employed as dopants, these halogens can significantly modify the optoelectronic properties of materials. From the perspective of halogen doping, we have successfully achieved the stabilization of crystal structures in CH3NH3PbX3, CH3NH3PbI3−xClx, CH3NH3PbI3−xBrx, and CH3NH3PbBr3−xClx, which are organic–inorganic hybrid perovskites. Utilizing first-principles density functional theory calculations with the CASTEP module, we investigated the optoelectronic properties of these structures by simulations. According to the calculations, a smaller difference in electronegativity between different halogens in doped structures can result in smoother energy bands, especially in CH3NH3PbI3−xBrx and CH3NH3PbBr3−xClx. The PDOS of the Cl-3p orbitals undergoes a shift along the energy axis as a result of variances in electronegativity levels. The optoelectronic performance, carrier mobility, and structural stability of the CH3NH3PbBr3−xClx system are superior to other systems like CH3NH3PbX3. Among many materials considered, CH3NH3PbBr2Cl exhibits higher carrier mobility and a relatively narrower bandgap, making it a more suitable material for the absorption layer in solar cells. This study provides valuable insights into the methodology employed for the selection of specific types, quantities, and positions of halogens for further research on halogen doping. [ABSTRACT FROM AUTHOR]

Transmission electron microscope (TEM) is thought as one powerful tool to imaging the atomic-level structure of organic inorganic hybrid perovskite (OIHP) materials, which provides valuable and essential guidance toward high performance OIHP-related devices. However, these OIHPs exhibit poor electron beam stability, severely limiting their practical applications in TEM. Here in this article, the application of TEM to obtain atomic-scale image of OIHPs, main obstacles in identifying the degradation product and future prospects of TEM in the characterization of OIHP materials are reviewed and presented. Three potential strategies (sample protection, low temperature technology, and low-dose technologies) are also proposed to overcome the current drawback of TEM technology. [ABSTRACT FROM AUTHOR]

We have synthesised and characterised 21 new ternary Pb(II) bromides with 16 different pyridine‐based organic cations by single crystal XRD measurements. The dominating composition is APbBr3 with 10 representatives, but also 6 examples for APb2Br5 were found. The systematic variation of topological aspects of the organic cations allowed conclusions on the influence of N−H⋅⋅⋅Br hydrogen bridges on the connectivity and bonding situation of the Pb−Br polyhedra. Additionally, it turned out, that further weak ionic interactions can have an influence, if the formation of N−H⋅⋅⋅Br hydrogen bridges is hindered by steric effects. In general, the high versatility of the dominating PbBr6 octahedra, and in some cases higher or lower coordination numbers, allows conclusions on the parameters that influence pattern and extent of the N−H⋅⋅⋅Br bridges as the strongest structure‐determining factor. Type and extent of N−H⋅⋅⋅Br bridges have also an impact on the distortion of the PbBr6 octahedra ranging from nearly regular PbBr6 octahedra to 2+2+2 and 1+2+2+1 patterns with significant lone pair activity. Finally, the connectivity mode of the octahedra relates to formation and strength of hydrogen bonds. [ABSTRACT FROM AUTHOR]

We have synthesised and characterised 21 new ternary Pb(II) bromides with 16 different pyridine‐based organic cations by single crystal XRD measurements. The dominating composition is APbBr3 with 10 representatives, but also 6 examples for APb2Br5 were found. The systematic variation of topological aspects of the organic cations allowed conclusions on the influence of N−H⋅⋅⋅Br hydrogen bridges on the connectivity and bonding situation of the Pb−Br polyhedra. Additionally, it turned out, that further weak ionic interactions can have an influence, if the formation of N−H⋅⋅⋅Br hydrogen bridges is hindered by steric effects. In general, the high versatility of the dominating PbBr6 octahedra, and in some cases higher or lower coordination numbers, allows conclusions on the parameters that influence pattern and extent of the N−H⋅⋅⋅Br bridges as the strongest structure‐determining factor. Type and extent of N−H⋅⋅⋅Br bridges have also an impact on the distortion of the PbBr6 octahedra ranging from nearly regular PbBr6 octahedra to 2+2+2 and 1+2+2+1 patterns with significant lone pair activity. Finally, the connectivity mode of the octahedra relates to formation and strength of hydrogen bonds. [ABSTRACT FROM AUTHOR]

Recently organic–inorganic hybrid perovskite (OIHP) has risen suddenly to become a superstar for spintronic applications. Fundamental understanding of its spin properties is of great importance for future advances of its applications in spin‐optoelectronic devices. In this work, the authors pioneer modulation of the spin Seebeck thermopower (SSTP) in a Pt/MAPbBr3/NiFe nonlocal structure via longitudinal spin Seebeck effect measurements. They unravel the effective magnon injection into the perovskite film from the NiFe layer, and the tunability of SSTP in this structure is easily realized through the optimization of morphology and component engineering of the OIHP film. First, upon biasing samples with a magnetic flux density during the preparation process, a high‐quality OIHP film can be obtained, in which the spin scattering can be reduced leading to the SSTP enhancement. Second, by doping Cr into the OIHP lattice, the increased magnetic moment density and the additional in‐plane inverse Rashba–Edelstein effect synergistically improve spin accumulation in the Pt layer and thus tune its SSTP. Unveiling those phenomena is important to understanding magnon transport in the OIHP interlayer, which is instructive for designing magnonic devices based on OIHP film. [ABSTRACT FROM AUTHOR]

Cl, Br, and I are elements in the halogen family, and are often used as dopants in semiconductors. When employed as dopants, these halogens can significantly modify the optoelectronic properties of materials. From the perspective of halogen doping, we have successfully achieved the stabilization of crystal structures in CH3NH3PbX3, CH3NH3PbI3−xClx, CH3NH3PbI3−xBrx, and CH3NH3PbBr3−xClx, which are organic–inorganic hybrid perovskites. Utilizing first-principles density functional theory calculations with the CASTEP module, we investigated the optoelectronic properties of these structures by simulations. According to the calculations, a smaller difference in electronegativity between different halogens in doped structures can result in smoother energy bands, especially in CH3NH3PbI3−xBrx and CH3NH3PbBr3−xClx. The PDOS of the Cl-3p orbitals undergoes a shift along the energy axis as a result of variances in electronegativity levels. The optoelectronic performance, carrier mobility, and structural stability of the CH3NH3PbBr3−xClx system are superior to other systems like CH3NH3PbX3. Among many materials considered, CH3NH3PbBr2Cl exhibits higher carrier mobility and a relatively narrower bandgap, making it a more suitable material for the absorption layer in solar cells. This study provides valuable insights into the methodology employed for the selection of specific types, quantities, and positions of halogens for further research on halogen doping.

Transmission electron microscope (TEM) is thought as one powerful tool to imaging the atomic-level structure of organic inorganic hybrid perovskite (OIHP) materials, which provides valuable and essential guidance toward high performance OIHP-related devices. However, these OIHPs exhibit poor electron beam stability, severely limiting their practical applications in TEM. Here in this article, the application of TEM to obtain atomic-scale image of OIHPs, main obstacles in identifying the degradation product and future prospects of TEM in the characterization of OIHP materials are reviewed and presented. Three potential strategies (sample protection, low temperature technology, and low-dose technologies) are also proposed to overcome the current drawback of TEM technology.

Micro/nano optoelectronic devices based on curved substrates play a significant role in the development of wearable devices, electronic skin, conformal sensors, conformal antennas, and soft robots. However, the current fabrication processes are oriented toward planar micro/nano devices, and the fabrication of such devices on curved substrates is challenging. Herein, a temperature‐gradient‐assisted nanoimprint‐based in situ micro/nano‐crystal growth method is proposed to fabricate high‐quality curved perovskite microwire crystal (MWC) arrays on curved surfaces. Based on this curved perovskite MWC array without bending‐induced defects, high‐performance curved photodetectors (responsivity = 414 A W−1, detectivity = 1.2 × 1014 Jones, and external quantum efficiency over 140 000%) with extraordinary stability (85% of original performance maintained for more than 2 years) are fabricated to realize a curved imaging device. These results provide insights into the application of high‐performance perovskite photodetectors in nonconformal optical systems. [ABSTRACT FROM AUTHOR]

The poor stability of organic–inorganic hybrid perovskites hinders its commercial application, which motivates a need for greater theoretical insight into its binding mechanism. To date, the binding mode of organic cation and anion inside organic–inorganic hybrid perovskites is still unclear and even contradictory. Therefore, in this work based on density functional theory (DFT), the binding mechanism between organic cation and anion was systematically investigated through electronic structure analysis including an examination of the electronic localization function (ELF), electron density difference (EDD), reduced density gradient (RDG), and energy decomposition analysis (EDA). The binding strength is mainly determined by Coulomb effect and orbital polarization. Based on the above analysis, a novel 2D linear regression descriptor that Eb = − 9.75Q2/R0 + 0.00053 V∙EHL − 6.11 with coefficient of determination R2 = 0.88 was proposed to evaluate the binding strength (the units for Q, R0, V, and EHL are |e|, Å, bohr3, and eV, respectively), revealing that larger Coulomb effect (Q2/R0), smaller volume of perovskite (V), and narrower energy difference (EHL) between the lowest unoccupied molecular orbital (LUMO) of organic cation and the highest occupied molecular orbital (HOMO) of anion correspond to the stronger binding strength, which guides the design of highly stable organic–inorganic hybrid perovskites. [ABSTRACT FROM AUTHOR]

As an important photovoltaic material, organic-inorganic hybrid perovskites have attracted much attention in the field of solar cells, but their instability is one of the main challenges limiting their commercial application. However, the search for stable perovskites among the thousands of perovskite materials still faces great challenges. In this work, the energy above the convex hull values of organic-inorganic hybrid perovskites was predicted based on four different machine learning algorithms, namely random forest regression (RFR), support vector machine regression (SVR), XGBoost regression, and LightGBM regression, to study the thermodynamic phase stability of organic-inorganic hybrid perovskites. The results show that the LightGBM algorithm has a low prediction error and can effectively capture the key features related to the thermodynamic phase stability of organic-inorganic hybrid perovskites. Meanwhile, the Shapley Additive Explanation (SHAP) method was used to analyze the prediction results based on the LightGBM algorithm. The third ionization energy of the B element is the most critical feature related to the thermodynamic phase stability, and the second key feature is the electron affinity of ions at the X site, which are significantly negatively correlated with the predicted values of energy above the convex hull (E hull ). In the screening of organic-inorganic perovskites with high stability, the third ionization energy of the B element and the electron affinity of ions at the X site is a worthy priority. The results of this study can help us to understand the correlation between the thermodynamic phase stability of organic-inorganic hybrid perovskites and the key features, which can assist with the rapid discovery of highly stable perovskite materials.

Organic–inorganic hybrid perovskites such as methylammonium lead iodide (MAPbI3) materials have recently attracted great attention due to their potential for photovoltaic applications. The performance and stability of these perovskite solar cells are sensitive to water and moisture in an ambient environment. Thus, an understanding of how water influences MAPbI3 and particularly the role of grain boundary (GB) defects is important for developing appropriate mitigation strategies. Herein, water molecular diffusion in ∑5‐(210) GB is investigated and compared with pristine MAPbI3 using first‐principles calculations. Water diffusion along the ∑5‐(210) GB is found to be facile with a 0.07 eV energy barrier while diffusion barrier from GB core to bulk is 0.24 eV. In contrast, the diffusion process in bulk MAPbI3 is relatively large 0.70 eV due to water interactions with the Pb–I network. Further, it is shown that water is more stable in the GB region compared with the pristine system. Thus, the strong thermodynamic and kinetic tendencies for water segregation to the GBs in MAPbI3 suggests that improving the crystallinity of MAPbI3 is an effective strategy to slow down water degradation processes in agreement with recent experimental results.

The explosive growth of the information era has put forward urgent requirements for ultrahigh-speed and extremely efficient computations. In direct contrary to charge-based computations, spintronics aims to use spins as information carriers for data storage, transmission, and decoding, to help fully realize electronic device miniaturization and high integration for next-generation computing technologies. Currently, many novel spintronic materials have been developed with unique properties and multifunctionalities, including organic semiconductors (OSCs), organic-inorganic hybrid perovskites (OIHPs), and 2D materials (2DMs). These materials are useful to fulfill the demand for developing diverse and advanced spintronic devices. Herein, these promising materials are systematically reviewed for advanced spintronic applications. Due to the distinct chemical and physical structures of OSCs, OIHPs, and 2DMs, their spintronic properties (spin transport and spin manipulation) are discussed separately. In addition, some multifunctionalities due to photoelectric and chiral-induced spin selectivity (CISS) are overviewed, including the spin-filter effect, spin-photovoltaics, spin-light emitting devices, and spin-transistor functions. Subsequently, challenges and future perspectives of using these multifunctional materials for the development of advanced spintronics are presented., (© 2023 Wiley‐VCH GmbH.)

Switchable spontaneous polarization is the vital property of ferroelectrics, which leads to other key physical properties such as piezoelectricity, pyroelectricity, and nonlinear optical effects, etc. Recently, organic-inorganic hybrid perovskites with 2D layered structure have become an emerging branch of ferroelectric materials. However, most of the 2D hybrid ferroelectrics own relatively low polarizations (<15 µC cm -2 ). Here, a strategy to enhance the polarization of these hybrid perovskites by using ortho-, meta-, para-halogen substitution is developed. Based on (benzylammonium) 2 PbCl 4 (BZACL), the para-chlorine substituted (4-chlorobenzylammonium) 2 PbCl 4 (4-CBZACL) ferroelectric semiconductor shows a large spontaneous polarization (23.3 µC cm -2 ), which is 79% larger than the polarization of BZACL. This large enhancement of polarization is successfully explained via ab initio calculations. The study provides a convenient and efficient strategy to promote the ferroelectric property in the hybrid perovskite family., (© 2023 Wiley-VCH GmbH.)

[Display omitted] • Two-dimensional organic–inorganic hybrid perovskites were identified based on our diagrammatic machine learning model with an accuracy of > 90 %. • A two-dimensional perovskite candidate designed from a visual pattern recognition projection was successfully synthesized. • Three rules for guiding the formation of two-dimensional organic–inorganic hybrid perovskites were extracted from the decision tree model. Two-dimensional (2D) organic–inorganic hybrid perovskites (OIHPs) have drawn increased attention due to rich physical properties such as ferroelectricity and photovoltaic properties. Nevertheless, it is challenging to discover novel 2D OIHPs within the vast chemical composition space. Herein, a diagrammatic machine learning model was employed to improve this issue. We collected 179 OIHPs with a variety of organic cations and screened out 6 features from 10,622 descriptors. Subsequently, a decision tree model was created to predict the dimensionality of OIHPs, achieving a LOOCV accuracy of 0.94 and a test accuracy of 0.89, respectively. Then, one candidate from a virtual space with 8256 samples was successfully synthesized, which was consistent with the prediction of the model. Finally, three rules were produced by visualization of the tree structure to generally discriminate 2D from non-2D OIHPs. It is believed that the diagrammatic model has reliability in identifying 2D OIHPs and will serve further property studies of OIHPs in the future. [ABSTRACT FROM AUTHOR]

Chemical modifications on aromatic spacers of 2D perovskites have been demonstrated to be an effective strategy to simultaneously improve optoelectronic properties and stability. However, its underlying mechanism is poorly understood. By using 2D phenyl-based perovskites ([C 6 H 5 (CH 2 ) m NH 3 ] 2 PbI 4 ) as models, the authors have revealed how the chemical nature of aromatic cations tunes the bandgap and charge transport of 2D perovskites by utilizing sum-frequency generation vibrational spectroscopy to determine the stacking arrangement and orientation of aromatic cations. It is found that the antiparallel slip-stack arrangement of phenyl rings between adjacent layers induces an indirect band gap, resulting in anomalous carrier dynamics. Incorporation of the CH 2 moiety causes stacking rearrangement of the phenyl ring and thus promotes an indirect to direct bandgap transition. In direct-bandgap perovskites, higher carrier mobility correlates with a larger orientation angle of the phenyl ring. Further optimizing the orientation angle by introducing a para-substituted element in a phenyl ring, higher carrier mobility is obtained. This work highlights the importance of leveraging stacking arrangement and orientation of the aromatic cations to tune the photophysical properties, which opens up an avenue for advancing high-performance 2D perovskites optoelectronics via molecular engineering., (© 2023 Wiley-VCH GmbH.)

Recent advances in the use of organic-inorganic hybrid perovskites have been investigated in a variety of applications, such as solar cells, photodetectors, light-emitting devices, and lasers, because of their outstanding semiconductor properties. Furthermore, the perovskite structure can host extrinsic elements, making it a promising candidate for battery applications. Previous studies have shown that organic-inorganic hybrid perovskites can be suitable anode materials for both lithium- and sodium-ion batteries. However, multivalent rechargeable batteries with perovskite materials have not yet been realized. Herein, we studied the electrochemical performance of three-dimensional (CH 3 NH 3 PbI 3 (MAPbI 3) and long-chain alkylammonium (C 4 H 9 NH 3) 2 (CH 3 NH 3) 3 Pb 4 I 13 ((i BA) 2 (MA) 3 Pb 4 I 13) thin films as electrode materials for rechargeable Al-ion batteries. Our results showed that (i BA) 2 (MA) 3 Pb 4 I 13 presented a specific capacity of 257 mAh g–1 at a current density of 0.1 A g−1 and delivered 108 mAh g–1 after 250 cycles at a current density of 0.3 A g−1 with a retention of as high as 91 %, demonstrating a crucial role of isobutyl amine (C 4 H 9 NH 3) due to the unique hydrogen-bonding interaction of isobutyl amine that hinders the shuttle effect of polyiodide. The results open a new direction for the use of organic–inorganic hybrid perovskites for new secondary aluminum ion batteries. [Display omitted] • We studied the electrochemical performance of 3D and LCA organic–inorganic hybrid perovskite thin films as electrode materials for rechargeable Al-ion batteries. • The LCA electrode yielded a specific capacity of 257 mAh g–1 at a current density of 0.1 A g−1 and delivered 108 mAh g–1 after 250 cycles at a current density of 0.3 A g−1 with a retention of as high as 91%. • The excellent performance can be attributed to the unique hydrogen-bonding interaction of isobutylamine, which effectively hindered the shuttle effect of polyiodide, as confirmed by ex-situ FT-IR, Raman, XPS, ESI-MS, and DFT calculations. [ABSTRACT FROM AUTHOR]

High-efficiency electromagnetic (EM) functional materials are the core building block of high-performance EM absorbers and devices, and they are indispensable in various fields ranging from industrial manufacture to daily life, or even from national defense security to space exploration. Searching for high-efficiency EM functional materials and realizing high-performance EM devices remain great challenges. Herein, a simple solution-process is developed to rapidly grow gram-scale organic-inorganic (MAPbX 3 , X = Cl, Br, I) perovskite microcrystals. They exhibit excellent EM response in multi bands covering microwaves, visible light, and X-rays. Among them, outstanding microwave absorption performance with multiple absorption bands can be achieved, and their intrinsic EM properties can be tuned by adjusting polar group. An ultra-wideband bandpass filter with high suppression level of -71.8 dB in the stopband in the GHz band, self-powered photodetectors with tunable broadband or narrowband photoresponse in the visible-light band, and a self-powered X-ray detector with high sensitivity of 3560 µC Gy air -1  cm -2  in the X-ray band are designed and realized by precisely regulating the physical features of perovskite and designing a novel planar device structure. These findings open a door toward developing high-efficiency EM functional materials for realizing high-performance EM absorbers and devices., (© 2023 Wiley-VCH GmbH.)

Transmission electron microscopy (TEM) is a powerful tool for unveiling the structural, compositional, and electronic properties of organic-inorganic hybrid perovskites (OIHPs) at the atomic to micrometer length scales. However, the structural and compositional instability of OIHPs under electron beam radiation results in misunderstandings of the microscopic structure-property-performance relationship in OIHP devices. Here, ultralow dose TEM is utilized to identify the mechanism of the electron-beam-induced changes in OHIPs and clarify the cumulative electron dose thresholds (critical dose) of different commercially interesting state-of-the-art OIHPs, including methylammonium lead iodide (MAPbI 3 ), formamidinium lead iodide (FAPbI 3 ), FA 0.83 Cs 0.17 PbI 3 , FA 0.15 Cs 0.85 PbI 3 , and MAPb 0.5 Sn 0.5 I 3 . The critical dose is related to the composition of the OIHPs, with FA 0.15 Cs 0.85 PbI 3 having the highest critical dose of ≈84 e Å -2 and FA 0.83 Cs 0.17 PbI 3 having the lowest critical dose of ≈4.2 e Å -2 . The electron beam irradiation results in the formation of a superstructure with ordered I and FA vacancies along <110> c , as identified from the three major crystal axes in cubic FAPbI 3 , <100> c , <110> c , and <111> c . The intragrain planar defects in FAPbI 3 are stable, while an obvious modification is observed in FA 0.83 Cs 0.17 PbI 3 under continuous electron beam exposure. This information can serve as a guide for ensuring a reliable understanding of the microstructure of OIHP optoelectronic devices by TEM., (© 2023 Wiley-VCH GmbH.)

Low-dimensional organic-inorganic hybrid perovskites possess unique microstructural, optical, and electrical properties and offer great application prospects in other fields in addition to optoelectronics. In this study, one-dimensional methylammonium lead iodide (MAPbI 3) nanowires (NWs) were fabricated using an antisolvent-assisted solution method with the addition of phenethylammonium iodide (PEAI). The effects of PEAI on the crystal growth, morphology and microstructure, photoluminescence (PL), and photoresponse performance of the NWs were investigated. The results showed that the addition of the appropriate amount of PEAI transformed the morphology of MAPbI 3 from micron-scale wires to elongated NWs with a high-aspect ratio. Scanning electron microscopy, X-ray diffraction, atomic force microscopy, scanning Kelvin probe microscopy, PL, and time-resolved PL spectroscopic characterizations were conducted, and the results confirmed that PEAI improved the microstructural properties of the as-prepared NWs and manifested surface passivation. The PEAI-treated MAPbI 3 NWs devices also exhibited a superior photoresponsivity as photodetectors compared with the untreated MAPbI 3 microwires devices. This study proposed a simple and effective method that can improve the microstructural and photoelectrical properties of low-dimensional MAPbI 3 crystals, which have a broad application potential for next-generation optoelectronic devices or detectors. • Nanowire-shaped MAPbI 3 with superior microstructural features were fabricated. • A novel approach of adding PEAI was presented to improve MAPbI 3 crystal properties. • PEAI-modified nanowires with larger crystallite size and smaller microstrain were obtained. • Emission and photoresponse properties were improved after PEAI treatment. • PEAI has a remarkable effect on the growth of low-dimensional MAPbI 3 crystals. [ABSTRACT FROM AUTHOR]

A new Zn-halide hybrid crystal based on pyrrolidine-derivative exhibits reversible phase transition at around 330 K/320 K (heating/cooling). [Display omitted] • (HNBNMP) 2 (ZnCl 4) (HNBNMP = N-bromomethyl-N-methylpyrrolidinium cation, compound 1), shows a reversible phase transition at 330/320 K (heating/cooling) through differential scanning calorimetry (DSC). • Variable-temperature single-crystal structural analysis and powder X-ray diffraction patterns verify the structural phase transition. • Variable-temperature dielectric measurements show the dielectric switching behavior indicating the potential application in the dielectric functional materials. We have successfully synthesized compound 1 (HNBNMP) 2 (ZnCl 4) (HNBNMP = N-bromomethyl-N-methylpyrrolidinium cation) through the slow evaporation method at room temperature. Several studies (differential scanning calorimetry measurements, single crystal structural analysis, variable-temperature powder X-ray diffraction and dielectric measurements) show that compound 1 has a reversible structural phase transition at around 330 K/320 K (heating/cooling), respectively. Variable-temperature powder X-ray diffraction patterns further demonstrate that compound 1 undergoes a phase transition. Meanwhile, the unique phase transition behavior was also confirmed by its remarkable dielectric and thermal anomalies around the phase transition point. The step-like dielectric switching in compound 1 can be mainly ascribed to the motional changes of polar components between room-temperature and high-temperature phases. This finding should stimulate further synthesis for switchable functional materials. [ABSTRACT FROM AUTHOR]

Defects in organic-inorganic hybrid perovskites (OIHPs) greatly influence their optoelectronic properties. Identification and better understanding of defects existing in OIHPs is an essential step towards fabricating high-performance perovskite solar cells. However, directly visualizing the defects is still a challenge for OIHPs due to their sensitivity during electron microscopy characterizations. Here, by using low dose scanning transmission electron microscopy techniques, we observe the common existence of antiphase boundary (APB) in CH 3 NH 3 PbI 3 (MAPbI 3), resolve its atomic structure, and correlate it to the electrical/ionic activities and structural instabilities. Such an APB is caused by the half-unit-cell shift of [PbI 6 ]4− octahedron along the [100]/[010] direction, leading to the transformation from corner-sharing [PbI 6 ]4− octahedron in bulk MAPbI 3 into edge-sharing ones at the APB. Based on the identified atomic-scale configuration, we further carry out density functional theory calculations and reveal that the APB in MAPbI 3 repels both electrons and holes while serves as a fast ion-migration channel, causing a rapid decomposition into PbI 2 that is detrimental to optoelectronic performance. These findings provide valuable insights into the relationships between structures and optoelectronic properties of OIHPs and suggest that controlling the APB is essential for their stability. By using low dose scanning transmission electron microscopy techniques, the atomic structure of the antiphase boundary (APB) in CH 3 NH 3 PbI 3 (MAPbI 3) is revealed. Based on the identified atomic configuration of APB, further density functional theory calculations reveal that the APB in MAPbI 3 does not introduce any deep-level defects and repels both electrons and holes while provides a fast-ion-diffusion channel for MA+, Pb2+ and I−, thus leading to a fast decomposition into PbI 2. [Display omitted] [ABSTRACT FROM AUTHOR]

The surface properties of organic-inorganic hybrid perovskites can strongly affect the efficiency and stability of corresponding devices. Even though different surface passivation methods are developed, the microscopic structures of solution-processed perovskite film surfaces are not systematically studied. This study uses low-temperature scanning tunneling microscopy to study the organic-inorganic hybrid perovskite thin films, MA 0.4 FA 0.6 PbI 3 and MAPbI 3 , synthesized by the spin-coating method. Flat surface structures, atomic steps, and crystal grain boundaries are resolved at an atomic resolution. The surface imperfections are also characterized, as well as the dominant defects. Simulations on different types of iodine vacancy configurations are performed by density functional theory calculations. In addition, it is observed that the surface iodine lattice structure is unstable during scanning. Tip scanning can also cause the vertical migration of surface iodine ions. The measurements provide the direct visualizations of the surface imperfections of the solution-processed perovskite films. They are essential for understanding the surface-related optoelectronic effects and rationally designing more efficient surface passivation methods., (© 2022 Wiley-VCH GmbH.)

Rubidium cation (Rb + ) addition is witnessed to play a pivotal role in boosting the comprehensive performance of organic-inorganic hybrid perovskite solar cells. However, the origin of such success derived from irreplaceable superiorities brought by Rb + remains ambiguous. Herein, grain-boundary-including atomic models are adopted for the accurate theoretical analysis of practical Rb + distribution in perovskite structures. The spatial distribution, covering both the grain interiors and boundaries, is thoroughly identified by virtue of synchrotron-based grazing-incidence X-ray diffraction. On this basis, the prominent elevation of the halogen vacancy formation energy, improved charge-carrier dynamics, and the electronic passivation mechanism in the grain interior are expounded. As evidenced by the increased energy barrier and suppressed microcurrent, the critical role of Rb + addition in blocking the diffusion pathway along grain boundaries, inhibiting halide phase segregation, and eventually enhancing intrinsic stability is elucidated. Hence, the linkage avalanche effect of occupied location dominated by subtle changes in Rb + concentration on electronic defects, ion migration, and phase stability is completely investigated in detail, shedding a new light on the advancement of high-efficiency cascade-incorporating strategies and perovskite compositional engineering., (© 2022 Wiley-VCH GmbH.)