Energy Barrier For Transition Research Articles

Confined-Coordination Induced Intergrowth of Metal-Organic Frameworks into Precise Molecular Sieving Membranes.

Metal-organic framework (MOF) membranes with rich functionality and tunable pore system are promising for precise molecular separation; however, it remains a challenge to develop defect-free high-connectivity MOF membrane with high water stability owing to uncontrollable nucleation and growth rate during fabrication process. Herein, we report on a confined-coordination induced intergrowth strategy to fabricate lattice-defect-free Zr-MOF membrane towards precise molecular separation. The confined-coordination space properties (size and shape) and environment (water or DMF) were regulated to slow down the coordination reaction rate via controlling the counter-diffusion of MOF precursors (metal cluster and ligand), thereby inter-growing MOF crystals into integrated membrane. The resulting Zr-MOF membrane with angstrom-sized lattice apertures exhibits excellent separation performance both for gas separation and water desalination process. It was achieved H2 permeance of ~1200 GPU and H2/CO2 selectivity of ~67; water permeance of ~8 L ⋅ m-2 ⋅ h-1 ⋅ bar-1 and MgCl2 rejection of ~95 %, which are one to two orders of magnitude higher than those of state-of-the-art membranes. The molecular transport mechanism related to size-sieving effect and transition energy barrier differential of molecules and ions was revealed by density functional theory calculations. Our work provides a facile approach and fundamental insights towards developing precise molecular sieving membranes.

Confined‐Coordination Induced Intergrowth of Metal–Organic Frameworks into Precise Molecular Sieving Membranes

AbstractMetal–organic framework (MOF) membranes with rich functionality and tunable pore system are promising for precise molecular separation; however, it remains a challenge to develop defect‐free high‐connectivity MOF membrane with high water stability owing to uncontrollable nucleation and growth rate during fabrication process. Herein, we report on a confined‐coordination induced intergrowth strategy to fabricate lattice‐defect‐free Zr‐MOF membrane towards precise molecular separation. The confined‐coordination space properties (size and shape) and environment (water or DMF) were regulated to slow down the coordination reaction rate via controlling the counter‐diffusion of MOF precursors (metal cluster and ligand), thereby inter‐growing MOF crystals into integrated membrane. The resulting Zr‐MOF membrane with angstrom‐sized lattice apertures exhibits excellent separation performance both for gas separation and water desalination process. It was achieved H2 permeance of ~1200 GPU and H2/CO2 selectivity of ~67; water permeance of ~8 L ⋅ m−2 ⋅ h−1 ⋅ bar−1 and MgCl2 rejection of ~95 %, which are one to two orders of magnitude higher than those of state‐of‐the‐art membranes. The molecular transport mechanism related to size‐sieving effect and transition energy barrier differential of molecules and ions was revealed by density functional theory calculations. Our work provides a facile approach and fundamental insights towards developing precise molecular sieving membranes.

Analysis of volatiles from the thermal decomposition of Amadori rearrangement products in the cysteine-glucose Maillard reaction and density functional theory study

The Amadori rearrangement products are an important flavor precursor in the Maillard reaction. Its thermal decomposition products usually contribute good flavors in foods. Therefore, investigating the thermal breakdown of Amadori products is significant for understanding the flavor forming mechanism in the Maillard reaction. In this study, volatiles from thermal decomposition of Amadori products in cysteine and glucose Maillard reaction was investigated by a thermal desorption cryo-trapping system combined with gas chromatography-mass spectrometry (GC-MS). A total of 60 volatiles were detected and identified. Meanwhile, the forming mechanism of 2-methylthiophene, a major decomposition product, was also investigated by using density functional theory. Seventeen reactions, 12 transition states, energy barrier and rate constant of each reaction were finally obtained. Results reveal that it is more likely for Amadori products of cysteine and glucose to undergo decomposition under neutral or weakly alkaline conditions.

Dual-Energy-Barrier Stable Superhydrophobic Structures for Long Icing Delay.

Using superhydrophobic surfaces (SHSs) with the water-repellent Cassie-Baxter (CB) state is widely acknowledged as an effective approach for anti-icing performances. Nonetheless, the CB state is susceptible to diverse physical phenomena (e.g., vapor condensation, gas contraction, etc.) at low temperatures, resulting in the transition to the sticky Wenzel state and the loss of anti-icing capabilities. SHSs with various micronanostructures have been empirically examined for enhancing the CB stability; however, the energy barrier transits from the metastable CB state to the stable Wenzel state and thus the CB stability enhancement is currently not enough to guarantee a well and appliable anti-icing performance at low temperatures. Here, we proposed a dual-energy-barrier design strategy on superhydrophobic micronanostructures. Rather than the typical single energy barrier of the conventional CB-to-Wenzel transition, we introduced two CB states (i.e., CB I and CB II), where the state transition needed to go through CB I and CB II then to Wenzel state, thus significantly improving the entire CB stability. We applied ultrafast laser to fabricate this dual-energy-barrier micronanostructures, established a theoretical framework, and performed a series of experiments. The anti-icing performances were exhibited with long delay icing times (over 27,000 s) and low ice-adhesion strengths (0.9 kPa). The kinetic mechanism underpinning the enhanced CB anti-icing stability was elucidated and attributed to the preferential liquid pinning in the shallow closed structures, enabling the higher CB-Wenzel transition energy barrier to sustain the CB state. Comprehensive durability tests further corroborated the potentials of the designed dual-energy-barrier structures for anti-icing applications.

Photodoping-modified charge density wave phase transition in WS2/1T-TaS2 heterostructure

Abstract Controlling collective electronic states holds great promise for the development of innovative devices. Here, we experimentally detect the modification of the charge density wave (CDW) phase transition within a 1T-TaS2 layer in a WS2/1T-TaS2 heterostructure using time-resolved ultrafast spectroscopy. Laser-induced charge transfer doping strongly suppresses the commensurate CDW (CCDW) phase, which results in a significant decrease in both the phase transition temperature (T c) and phase transition stiffness (PTS). We interpret that photo-induced hole doping, when surpassing a critical threshold value of ~1018/cm3, sharply decreases the phase transition energy barrier. Our results provide new insights into controlling the CDW phase transition, paving the way for optical-controlled novel devices based on CDW materials.

Bidirectional tandem catalysis coupled with interface engineering and Se vacancies for accelerating the polysulfide conversion

The shuttling of long-chain LiPSs (Li2Sn, 4 ≤ n ≤ 8) and the sluggish conversion from Li2S4 to Li2S represent two primary challenges hindering the fast multi-step transformations of lithium-sulfur (Li-S) batteries. Here, we propose a bidirectional tandem catalytic strategy to promote polysulfide conversions. A novel nanostructured catalyst consisting of hollow bimetallic selenide (ZnSe/SnSe2) cubes with dual-active centers, heterogeneous interfaces and selenium-rich vacancies was synthesized. Experimental and theoretical calculations confirmed that ZnSe and SnSe2 selectively reduced the thermodynamic transition energy barrier of S8→Li2S4 and Li2S4→Li2S to achieve baton-relay-like conversion of polysulfides. Moreover, the synergistic effect of ZnSe and SnSe2 significantly reduced the activation barrier of Li2S reoxidation during the charging process, and achieved an efficient bidirectional catalytic conversion. In situ Raman analysis confirmed that ZnSe/SnSe2 effectively inhibited the shuttle effect. As a result, a battery with ZnSe/SnSe2 interlayer delivered high specific capacity of 1269.5 mAh g−1 at 0.2 C, and excellent rate capability (680.4 mAh g−1 at 4 C). Remarkably, the battery maintained cycling stability with only 0.086% capacity degradation per cycle after 500 cycles at 2 C. This work provides a new path for designing electrocatalyst towards precise control of catalytic processes in Li-S batteries.

A novel pathological mutant reveals the role of torsional flexibility in the serpin breach in adoption of an aggregation-prone intermediate.

Mutants of alpha-1-antitrypsin cause the protein to self-associate and form ordered aggregates ('polymers') that are retained within hepatocytes, resulting in a predisposition to the development of liver disease. The associated reduction in secretion, and for some mutants, impairment of function, leads to a failure to protect lung tissue against proteases released during the inflammatory response and an increased risk of emphysema. We report here a novel deficiency mutation (Gly192Cys), that we name the Sydney variant, identified in a patient in heterozygosity with the Z allele (Glu342Lys). Cellular analysis revealed that the novel variant was mostly retained as insoluble polymers within the endoplasmic reticulum. The basis for this behaviour was investigated using biophysical and structural techniques. The variant showed a 40% reduction in inhibitory activity and a reduced stability as assessed by thermal unfolding experiments. Polymerisation involves adoption of an aggregation-prone intermediate and paradoxically the energy barrier for transition to this state was increased by 16% for the Gly192Cys variant with respect to the wild-type protein. However, with activation to the intermediate state, polymerisation occurred at a 3.8-fold faster rate overall. X-ray crystallography provided two crystal structures of the Gly192Cys variant, revealing perturbation within the 'breach' region with Cys192 in two different orientations: in one structure it faces towards the hydrophobic core while in the second it is solvent-exposed. This orientational heterogeneity was confirmed by PEGylation. These data show the critical role of the torsional freedom imparted by Gly192 in inhibitory activity and stability against polymerisation.

Phase transition mechanism of CsPbI2Br perovskite films induced by moisture

The humidity stability and phase transition mechanism of the all-inorganic perovskite CsPbI2Br based on an optimized dual-source co-evaporation preparation process are investigated at the film interface level. It is found that the CsPbI2Br films annealed at 300 °C for several minutes exhibit a best crystallinity and photoelectric properties. The as-grown CsPbI2Br film is confirmed to be a α phase with a dark brown cubic crystal structure and an average visible transparency of 35.9%. But it will be transformed into its δ phase with a transparent orthorhombic crystal structure and an average visible transparency of 80.3% after a certain amount of moisture exposure. Compared with the α phase film, the electronic structure of the δ phase has also changed significantly with a VBM shift of about 0.32 eV to high binding energy. The results of AR-XPS show that the water molecules in perovskite CsPbI2Br after a moisture exposure only adsorb on the surface rather than penetrate the interior of the lattice. When water molecules adsorb on the lattice surface, halide ions should migrate towards the lattice surface due to their high hydration enthalpy, resulting in halide vacancies within the lattice and causing the reduction of energy barrier for phase transition from α phase to δ phase. So the CsPbI2Br film will transform from its α phase to δ phase induced by water vapor, and this phase transition will be reversed to some extent after another annealing.

Anion modulate the morphological and electronic structure of NiFe-based electrocatalyst for efficient urea oxidation-assisted water electrolysis

Renewable energy-driven water electrolysis is considered as an environmentally friendly hydrogen (H2) production technology. Replacing the oxygen evolution reaction (OER) with the urea oxidation reaction (UOR) is a more effective way to improve the energy efficiency of H2 generation. Herein, a highly efficient 2D NiFeMo-based UOR catalyst and 1D NiFeMo-based HER catalyst are prepared by adjusting the concentration of MoO4‒. The MoO4‒ can serve as the key regulator to adjust the balance between the electrolytic dissociation (α) of the reactants and the supersaturation (S) to modulate the morphological and electronic structure. The prepared 2D NiFeMo nanosheet UOR catalyst and 1D NiFeMo nanorod HER catalyst can achieve a current density of 100 mA cm−2 at a potential of 1.36 and 0.062 V, respectively. In a HER/UOR system, a cell voltage of 1.58 V is needed to achieve a current density of 100 mA cm−2. The HER/UOR system operated stably for over 60 h with 3 times the direct water electrolysis current density. Moreover, the in situ Raman characterization coupled with XPS analysis clarifies that the addition of high-valence Mo can lower the transition energy barrier between the low and high oxidation state of Ni, which in turn lowers the overpotential of UOR. This work provides a novel strategy for synthesizing morphology-dependent electrocatalysts for different catalytic systems.

Studying Plastic Deformation Mechanism in β-Ti-Nb Alloys by Molecular Dynamic Simulations

Using molecular dynamics (MD) simulations, the transition of the plastic deformation mechanism of Ti-Nb alloys during the tensile process was studied, and the effects of temperature, Nb composition, and strain rate on the deformation mechanism were also investigated. The results show that the deformation process of Ti-Nb alloys involves defect formation, followed by twinning and ω-phase transition, and ultimately, dislocation slip occurs. The <111>{112} slip makes the ω-phase easily overcome the transition energy barrier, inducing the phase transition in the twinning process. Increasing temperature will enhance the plasticity and reduce the strength of the material, while increasing Nb composition will have the opposite effect on the deformation. The simulations show a competition between twinning and dislocation slip mechanisms. With the increase in Nb content, the plastic deformation mechanism of the alloy will change from twinning to dislocation slip. In addition, the plastic strain range increases with the increase in the deformation rate in Ti-Nb alloys. At a higher strain rate, the alloy’s plastic strain range is affected by various deformation mechanisms, which significantly influence the plasticity of the material. The findings of this study provide further insights into the design of Ti-Nb-based alloys.

Renewing Halogen Substitution Strategy for the Rational Design of High‐Curie Temperature Metal‐Free Molecular Antiferroelectrics

AbstractMetal‐free molecular antiferroelectric (AFE) holds a promise for energy storage on account of its unique physical attributes. However, it is challenging to explore high‐curie temperature (Tc) molecular AFEs, due to the lack of design strategies regarding the rise of phase transition energy barriers. By renewing the halogen substitution strategy, we have obtained a series of high‐Tc molecular AFEs of the halogen‐substituted phenethylammonium bromides (x‐PEAB, x=H/F/Cl/Br), resembling the binary stator‐rotator system. Strikingly, the p‐site halogen substitution of PEA+ cationic rotators raises their phase transition energy barrier and greatly enhances Tc up to ~473 K for Br‐PEAB, on par with the record‐high Tc values for molecular AFEs. As a typical case, the member 4‐fluorophenethylammonium bromide (F‐PEAB) shows notable AFE properties, including high Tc (~374 K) and large electric polarization (~3.2 μC/cm2). Further, F‐PEAB also exhibits a high energy storage efficiency (η) of 83.6 % even around Tc, catching up with other AFE oxides. This renewing halogen substitution strategy in the molecular AFE system provides an effective way to design high‐Tc AFEs for energy storage devices.

Renewing Halogen Substitution Strategy for the Rational Design of High-Curie Temperature Metal-Free Molecular Antiferroelectrics.

Metal-free molecular antiferroelectric (AFE) holds a promise for energy storage on account of its unique physical attributes. However, it is challenging to explore high-curie temperature (Tc) molecular AFEs, due to the lack of design strategies regarding the rise of phase transition energy barriers. By renewing the halogen substitution strategy, we have obtained a series of high-Tc molecular AFEs of the halogen-substituted phenethylammonium bromides (x-PEAB, x=H/F/Cl/Br), resembling the binary stator-rotator system. Strikingly, the p-site halogen substitution of PEA+ cationic rotators raises their phase transition energy barrier and greatly enhances Tc up to ~473 K for Br-PEAB, on par with the record-high Tc values for molecular AFEs. As a typical case, the member 4-fluorophenethylammonium bromide (F-PEAB) shows notable AFE properties, including high Tc (~374 K) and large electric polarization (~3.2 μC/cm2). Further, F-PEAB also exhibits a high energy storage efficiency (η) of 83.6 % even around Tc, catching up with other AFE oxides. This renewing halogen substitution strategy in the molecular AFE system provides an effective way to design high-Tc AFEs for energy storage devices.

Role of amorphous phase in II-I transition of iPB-1/iPP blends

Isotactic polybutene-1 (iPB-1) possesses excellent physical and mechanical properties, but its applications are limited owing to the slow II-I transition after melt processing. The concerned II-I transition mechanism is a long-lasting hot topic. After an isotactic polypropylene (iPP) was melt-blended into iPB-1, a good model system for II-I transition study to discuss on roles of amorphous phase was consequently obtained with amorphous phase tuned but form II crystalline structures almost kept fixed according to the affected crystallization and melting behaviors of iPB-1 in iPB-1/iPP blends. Both DSC and FTIR results revealed the enhanced II-I transition behaviors of iPB-1 in the blends and FTIR results especially confirmed form I direct crystallization from amorphous phase of iPB-1/iPP blends prior to form II consumption due to II-I transition. The earlier the direct form I crystallization, the faster II-I transition of iPB-1 in the iPB-1/iPP blends. It was proposed that form I direct crystallization of the iPB-1 chain segments which have ability to crystallize but remained in the amorphous phase lowered the energy barrier of transition from adjacent form II crystals to packed-mesophases due to the local volume contract resulting in a stretch to iPB-1 chains with parts contained in the adjacent form II crystals. Consequently, the II-I transition of adjacent form II crystals were triggered to start and it generated a ripple effect on the entire II-I transition process. The results are of great significance on understanding of iPB-1 II-I transition process and also of importance for iPB-1 industrial applications.

The structural stability of Mn3Sn Heusler compound under high pressure

Pressure engineering has attracted growing interest in the understanding of structural changes and structure-property relations of layered materials. In this study, we investigated the effect of pressure on the crystal structure of Mn3Sn. In-situ high-pressure x-ray diffraction experiments revealed that Mn3Sn maintained hexagonal lattice symmetry within the pressure range of ambient to 50.4 GPa. The ratio of lattice constants c/a is almost independent of the pressure and remains constant at 0.80, indicating a stable cell shape. Density functional theory calculations revealed the strong correlation between the crystal structure and the localization of d electrons. The Mn3Sn has been found in flat energy bands near the Fermi level, exhibiting a large density of states (DOS) primarily contributed by the d electrons. This large DOS near the Fermi level increases the energy barrier for a phase transition, making the transition from the hexagonal phase to the tetragonal phase challenging. Our results confirm the structural stability of Mn3Sn under high pressure, which is beneficial to the robustness of spintronic devices.

Highly Crystalline Poly(heptazine imide)-Based Carbonaceous Anodes for Ultralong Lifespan and Low-Temperature Sodium-Ion Batteries.

Carbon nitrides with layered structures and scalable syntheses have emerged as potential anode choices for the commercialization of sodium-ion batteries. However, the low crystallinity of materials synthesized through traditional thermal condensation leads to insufficient conductivity and poor cycling stability, which significantly hamper their practical applications. Herein, a facile salt-covering method was proposed for the synthesis of highly ordered crystalline C3N4-based all-carbon nanocomposites. The sealing environment created by this strategy leads to the formation of poly(heptazine imide) (PHI), the crystalline phase of C3N4, with extended π-conjugation and a fully condensed nanosheet structure. Meanwhile, theoretical calculations reveal the high crystallinity of C3N4 significantly reduces the energy barrier for electron transition and enables the generation of efficient charge transfer channels at the heterogeneous interface between carbon and C3N4. Accordingly, such nanocomposites present ultrastable cycling performances over 5000 cycles, with a high reversible capacity of 245.1 mAh g-1 at 2 A g-1 delivered. More importantly, they also exhibit an outstanding low-temperature capacity of 196.6 mAh g-1 at -20 °C. This work offers opportunities for the energy storage use of C3N4 and provides some clues for developing long-life and high-capacity anodes operated under extreme conditions.

Elastocaloric effect with plateau-shape adiabatic temperature change in Ni–Co–Fe–Ga strain glass alloy

Elastocaloric effect (eCE) is a very promising candidate for using in non-vapor compression refrigeration, which is highly efficient and eco-friendly. However, designing elastocaloric alloys with a wide reversible working temperature window at low stress is still challenging. In this work, the transition behaviors, microstructural evolutions and the eCE of a series of Ni55−x Co x Fe19Ga27 alloys were systematically studied. The Ni44Co11Fe19Ga27 strain glass (STG) alloy exhibits a plateau-shape eCE, which show an average temperature change (ΔT Adia) of ∼2.3 K covering a wide reversible working temperature range (ΔT rev) from 135 K to 200 K. The unique eCE behavior of STG stems from that the random distribution of local free energy of the martensite coupled with the small transition energy barriers, which leads to a wide transition-temperature range and decreased hysteresis. The Ni44Co11Fe19Ga27 STG alloy achieves a balance between the considerable ΔT Adia and wide ΔT rev, resulting in an optimal comprehensive elastocaloric performance and contributing to improving the efficiency of elastocaloric refrigeration.

First-principles prediction of ferroelectric Janus Si2XY (X/Y = S/Se/Te, X ≠ Y) monolayers with negative Poisson's ratios.

Nowadays, two-dimensional (2D) materials with Janus structures evoke much attention due to their unique mechanical and electronic properties. In this work, Janus Pma2-Si2XY (X/Y = S/Se/Te, X ≠ Y) ferroelectric monolayers are firstly proposed and systematically investigated by first-principles calculations. These monolayers exhibit remarkable mechanical properties, including small Young's modulus values, negative Poisson's ratios (NPRs) and large critical strains, reflecting their exceptional flexibility and stretchability. More strikingly, the novel structures of Si2STe and Si2SeTe also endow them with in-plane spontaneous polarization (Ps) and low energy barrier for phase transition, with Ps and energy barrier values being 1.632 × 10-10 C m-1 and 159 meV for Si2STe and 1.149 × 10-10 C m-1 and 196.6 meV for Si2SeTe. The ab initio molecular dynamics (AIMD) simulations reveal high Curie temperatures (Tc) for Si2STe and Si2SeTe, ranging between 1300 K and 1400 K. Additionally, Si2XY monolayers exhibit high anisotropic carrier mobility (∼103 cm2 V-1 s-1) and an extraordinary light absorption coefficient (∼105 cm-1). Our research not only broadens the family of 2D Janus ferroelectric materials, but also demonstrates their potential applications in nanomechanical, nanoelectronic and optoelectronic devices.

Phase transition in WSe2-xTex monolayers driven by charge injection and pressure: a first-principles study.

Alloying strategies permit new probes for governing structural stability and semiconductor-semimetal phase transition of transition metal dichalcogenides (TMDs). However, the possible structure and phase transition mechanism of the alloy TMDs, and the effect of an external field, have been still unclear. Here, the enrichment of the Te content in WSe2-xTex monolayers allows for coherent structural transition from the H phase to the T' phase. The crystal orbital Hamiltonian population (COHP) uncovers that the bonding state of the H phase approaches the high-energy domain near the Fermi level as the Te concentration increases, posing a source of structural instability followed by a weakened energy barrier for the phase transition. In addition, the structural phase transition driven by charge injection opens up new possibilities for the development of phase-change devices based on atomic thin films. For WSe2-xTex monolayers with the H phase as the stable phase, the critical value of electron concentration triggering the phase transition decreases with an increase in the x value. Furthermore, the energy barrier from the H phase to the T' phase can be effectively reduced by applying tensile strain, which could favor the phase switching in electronic devices. This work provides a critical reference for controllable modulation of phase-sensitive devices from alloy materials with rich phase characteristics.

Valence state of V combined with D-tartaric acid and heat treatment affect sodium storage performance of NASICON-type multiphase composite

The polyanionic compound Na3V2(PO4)3 (NVP) and Na3V2(PO4)2F3 (NVPF) are promising cathode materials for sodium-ion batteries, but their poor electronic conductivity affects the electrochemical performance and the output energy density. The easy interconversion between V4+ and V5+ in the solution appears due to the weak bonds of D-tartaric acid, which lowers the energy barrier for further transition to V3+ and results in an excess V3+ in the product. A small amount of NVPF/C is converted to NVP/C due to the volatility of fluorine after heat treatment. D-tartaric acid as a carbon source forms a 3D network structure after calcination, thresholds the growth of NVP or NVPF and hinders the volume expansion during sodium storage. The initial discharge specific capacity of NVPF/C-650 is 85 mAh g−1 at 5C, and remains 59.2 mAh g−1 after 1000 cycles, which is related to the low charge transfer resistance, rapid Na+ ion diffusion and the pseudocapacitance effect. The binding of V and the carbon source in the solution affects the content of V3+/V4+ content, and the annealing temperature affects the formation and composition of the conducting carbon, both of which influence the electrochemical performance. This result provides a concept for possible screening of the carbon source for sodium storage materials with excellent performance.

(Invited) Achieving Stable Black-CsPbI3 Thin-Films for Opto-Electronic Applications

Halide perovskite materials, particularly CsPbI3, have emerged as promising candidates for optoelectronic applications, including solar cells, due to their favorable bandgap of ~1.7 eV for tandem solar cells with silicon-based counterparts. However, their widespread adoption is hindered by their instability and reactivity under ambient conditions, especially to moisture and oxygen. The black phase CsPbI3 polymorphs (α, β, and γ) are only stable at elevated temperatures, and at room temperature (RT), they transform to a yellow, nonperovskite phase (δ) with a wider bandgap of ~2.8 eV, leading to a loss of device performance. To address this challenge, various approaches have been explored to increase the stability of the black phase of CsPbI3 thin films under ambient conditions.[1]One approach is based on interface engineering to induce crystal strain, which increases the stabilization time of the black phase. Thin films of CsPbI3 are prepared on substrates with different thermal expansion coefficients, leading to interfacial strain when quenched from high temperatures (> 320 °C) to RT. This interfacial strain increases the stability of the black phase from a few seconds in bulk polycrystalline samples to a few minutes in thin films, as shown in Fig. 1(a).[2] Additionally, black phase stabilization has been enhanced to a few hours by introducing minimal amounts (< 5%) of dopant elements in the Pb site of CsPbI3, which modifies the texture and generates microstrain in the polycrystalline perovskite films (see Fig. 1(b)).[3] The dopants locally disrupt the normal bonding arrangement and manipulate strains/distortions, and structural relaxation around the dopants is mediated by dynamic disorder and the relatively soft elastic constants of halide perovskite, resulting in the stabilization of the required crystallographic phase.Furthermore, annealing of CsPbI3 thin films in the presence of oxygen has been explored as another approach to increase the stability of the black phase (stable for a few days). Heating the films under oxygen leads to surface oxidation and the formation of Pb-O bonds, resulting in the gathering of Pb and O atoms and the formation of lead oxide. The replacement of I atoms in the inorganic frameworks by O atoms tends to form volatile iodine (I2), but PbI2 is typically detected as the dominant product of degradation during heating in a dry air environment (Fig. 1(c)).[4] The oxidation products on the surface could potentially serve as a protective layer to inhibit further oxidation.Another highly effective approach to enhance the stability of the black phase CsPbI3 in perovskite thin films and devices is through the implementation of coarse photolithography to embed a PbI2-based interfacial microstructure.[5] The resulting films, adorned with a tessellating microgrid ((Fig. 1(d))), display remarkable resistance to moisture-induced decay and demonstrate prolonged stability of the black phase, persisting beyond 2.5 years even in dry environments. This remarkable stability can be attributed to the significant increase in the phase transition energy barrier and the effective limitation of potential yellow phase formation to structurally isolated domains within the microgrid.In summary, our laboratory has effectively implemented various methods to enhance the durability of black phase CsPbI3 thin films when exposed to ambient conditions. These methods comprise inducing interfacial strain, introducing bulk strain through doping, embedding interfacial microstructures, and surface oxidation. These techniques have demonstrated encouraging outcomes in maintaining the black phase of CsPbI3 for extended durations, ranging from a few minutes to several months, and exhibit significant potential for the advancement of practical applications of CsPbI3-based perovskite solar cells. Further exploration and advancement in this direction are anticipated to contribute to achieving long-lasting and efficient perovskite devices.[1] Acc. Mater. Res., 2020, 1, 1, 3–15[2] Science, 2019, 365, 679-684[3] J. Am. Chem. Soc., 2021, 143, 28, 10500–10508[4] unpublished results[5] Nature Commun., 2022, 13, 7513. Figure 1