Superior Phase Stability Research Articles

The influence of the elemental valence on the thermophysical properties of high entropy (La0.2Sm0.2Eu0.2Yb0.2Y0.2)2(Ce0.5Zr0.5)2O7 coatings for thermal barrier application

Commercial yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are no longer sufficient for the stringent demands in the high operating temperature and excellent thermophysical properties of the high-performance gas turbines and aviation engines. High entropy ceramics, distinguished by their superior thermophysical properties, have risen as a potential substitute for TBCs. However, the realm of atmospheric plasma spraying (APS) in the creation of these advanced TBCs remains relatively unexplored. In this work, three distinct high-entropy (La0.2Sm0.2Eu0.2Yb0.2Y0.2)2(Ce0.5Zr0.5)2O7 coatings were developed through the meticulous alteration of spraying power. The effects of spraying power on the microstructure, valence states of constituent elements and thermophysical properties of the coatings were deeply investigated. The results indicated that all the as-sprayed coatings exhibit a defect fluorite structure. Spraying power does have a significant impact on the thermophysical properties of the coatings. With the decrease in spraying power, the thermal conductivity of the coatings shows a progressive reduction, whereas the coefficient of thermal expansion (CTE) exhibits a gradual increase. This trend is closely related to valence states of constituent elements in the coatings. The resulting coating exhibits a low thermal conductivity of 0.54 W⋅m-1⋅K-1, a high CTE of 11.22×10-6·K-1 and a superior phase stability at elevated temperatures.

In Situ Fabrication of Highly Efficient and Stable Cs2NaInCl6: Sb3+@PVDF Composite Films for Optoelectronic Devices.

Lead-free double perovskites (DPs) have superior phase stability and optical properties, which make them competitive for future applications in illumination and displays. However, the preparation of DPs was mainly based on high-temperature heating and hydrochloric acid as a solvent to form powders, which increased the risk and cost of the preparation process and limited its further application. In this study, the growth of Cs2NaInCl6: Sb3+ DPs in polyvinylidene difluoride (PVDF) films was achieved using an in situ fabrication strategy with DMSO as the solvent. The prepared Cs2NaInCl6: Sb3+@PVDF composite films (CFs) can achieve a bright blue emission under 302 nm irradiation. To achieve the optimal luminescent performance of CFs, the photoluminescence (PL) intensity of Cs2NaInCl6: Sb3+@PVDF CFs under various in situ preparation conditions was compared. In addition, the photoluminescence quantum yield (PLQY) of CFs was increased from 0.72% to 83.77% by adjusting the doping amount of Sb3+, and the fluorescence lifetimes t1 and t2 were 131.08 and 1048.52 ns, respectively. Temperature-dependent PL spectroscopy and density functional theory (DFT) calculations indicate that these excellent optical properties are derived from the self-trapped excitons (STEs) at the [SbCl6]3- octahedron and [InCl6]3- octahedron connected via Cl-Na-Cl. The CFs also demonstrated excellent environmental stability, maintaining a relatively stable PL intensity even under conditions of water immersion, high temperatures, and ultraviolet (UV) radiation. Finally, we used the CFs to assemble a blue light-emitting device (LED), which showed good and stable blue emission performance at different currents. This work can provide a new idea for preparing DPs, which is conducive to promoting their commercial application in high-performance optoelectronic devices.

Enhanced thermoelectric performance of Cr-doped ZnSb through lattice thermal conductivity reduction below the phonon glass limit

Zinc antimonide (ZnSb) is a promising thermoelectric material due to its economic viability, elemental abundance, and superior phase stability compared to other Zn-Sb compounds. However, its widespread application is hindered by a low figure-of-merit (zT). Extensive research has explored doping, alloying, and nanostructuring to improve zT. This study investigates the impact of Cr doping in CryZn1-ySb (y = 0.0 – 0.03). Cr doping with y = 0.01 significantly reduces lattice thermal conductivity below the phonon glass limit. Debye-Callaway model calculations suggest a combined effect of point defects and decreased grain size caused by Cr incorporation. This reduction translates to enhanced thermoelectric performance, with the y = 0.01 sample exhibiting a 70 % improvement in zT at 673 K, reaching ∼0.67. Exceeding the Cr substitution limit leads to the formation of a detrimental secondary CrSb2 phase, increasing thermal conductivity. The Single Parabolic Band model calculations predict further zT enhancement in y = 0.01 sample to ∼0.2 at 300 K through optimized carrier concentration (307 % improvement in zT). These findings demonstrate the potential for significant zT improvement in ZnSb via defect engineering and carrier concentration tuning.

Construction Au/FAPbI3 Schottky Heterojunction towards a High-Speed Electron Transfer Channel for High-Performance Perovskite Quantum Dot Solar Cells.

Formamidinium lead triiodide quantum dot (FAPbI3 QD) exhibits substantial potential in solar cells due to its suitable band gap, extended carrier lifetime, and superior phase stability. However, despite great attempts toward reconfiguring the surface chemical environment of FAPbI3 QDs, achieving the optimal efficiency of charge carrier extraction and transfer in cells remains a challenge. To circumvent this problem, we selectively introduced Au/FAPbI3 Schottky heterojunctions by reducing Au+ to Au0 and subsequently anchoring them on the surface of FAPbI3 QDs, which acts as a light-harvesting layer and establishes high-speed electron transfer channels (Au dot ↔ Au dot). As a result, the champion photoelectric conversion efficiency of solar cells reached 13.68%, a significant improvement over 11.19% of that of FAPbI3-based solar cells. The enhancement is attributed to efficient and directed electron transfer as well as a more aligned energy level arrangement. This work constructed Au/FAPbI3 QD Schottky heterojunctions, providing a viable strategy to enhance QD electron coupling for high-performance optoelectronic applications.

Colloidal and interfacial properties of spray dried pulse protein-blueberry polyphenol particles in model dispersion systems

The phytochemical composition and physicochemical attributes of polyphenol-enriched protein particle ingredients produced with pulse proteins (e.g. chickpea protein, pea protein, and a chickpea-pea protein blend) and polyphenols recovered from wild blueberry pomace were investigated for colloidal and interfacial properties. Anthocyanins were the major polyphenol fraction (27.74–36.47 mg C3G/g) of these polyphenol-rich particles (44.95–62.08 mg GAE/g). Dispersions of pea protein-polyphenol particles showed a superior phase stability before and after heat treatment compared to the chickpea pea protein-polyphenol system. This observation was independent of the added amount of NaCl in the dispersion. In general, at quasi equilibrium state, pulse protein-polyphenol particles and parental pulse protein ingredients showed similar oil-water interfacial tension. However, pea protein-polyphenol particles demonstrated a reduced diffusion-driven oil-water interfacial adsorption rate constant compared to the parental pea protein ingredient. Overall, the obtained results suggest application potential of pea protein-polyphenol particles as a functional food/beverage ingredient.

Effects of B2 ordered structure on the mechanical properties of TiZrHfCoNiCu high-entropy alloy

High-entropy alloys (HEAs) were once considered to be typical disordered solid solutions with various atoms randomly distributed in a lattice. Recent studies have found that owing to the chemical complexity of multiple primary elements, HEAs may also form ordered structures that directly influence their mechanical properties. In this study, B2-ordered and body-centered-cubic-disordered structures of TiZrHfCoNiCu HEAs were established using the special quasi-random structure method. The results of first principles calculations and ultrasonic wave velocity measurements indicated that the B2-ordered TiZrHfCoNiCu HEA exhibited superior phase stability, structural stability, and mechanical properties such as strength and hardness. Significantly, the results of this study revealed the physical mechanisms underlying the excellent mechanical properties of ordered HEAs and can guide their design and development accordingly.

Ag interlayer's influence on microstructure and mechanical properties of laser-welded Ta/304L joints

Tantalum and 304L possess unique properties for aerospace applications. Ta offers high temperature and acid/alkali resistance, while 304L is cost-effective with excellent corrosion resistance. Joining Ta and 304L optimises design, lowers costs and meets specific requirements. This study examined laser lap welding of 0.6 mm Ta and 304L with/without silver interlayer. Joint structure and properties were analysed to reveal the influence of detrimental phases, with first principles calculations for TaFe2 and TaCr2. Without Ag interlayer, the joint had 1857.19 N tensile shear force and 530 HV average weld zone hardness. Adding Ag reduced TaFe2 formation, improving tensile shear strength to 2100.30 N with 460 HV average hardness. First principles calculation confirmed TaCr2's superior phase stability over TaFe2.

Comparative investigation on the hot corrosion failure of YSZ and GdYb-YSZ double-ceramic-layer thermal barrier coatings under Na2SO4+V2O5 molten salts

The 5.2Gd2O3-5.6Yb2O3-9.5Y2O3 co-doped ZrO2 (GdYb-YSZ) double-ceramic-layer (DCL) thermal barrier coatings (TBCs) were prepared by atmospheric plasma spraying (APS) in this work. Hot corrosion behavior and failure mechanism of the APS GdYb-YSZ DCL and single-layer yttria partially stabilized zirconia (YSZ) TBCs under the Na2SO4+V2O5 molten salts were comparably investigated. The YSZ coating suffered from severe breakage after the hot corrosion test due to its poor corrosion resistance and easy infiltration by molten salts. In contrast, GdYb-YSZ DCL coating exhibited a better resistance to crack propagation and a significantly longer corrosion lifetime than the YSZ coating, which was attributed to the protective effect of the upper GdYb-YSZ layer. On the one hand, the superior phase stability of the GdYb-YSZ DCL coating could slow down the generation speed of phase transformation stress. On the other hand, the higher corrosion reaction rate of the upper GdYb-YSZ layer could suppress the further infiltration of molten salts into the inner TBCs, which improved the structural integrity of TBCs in corrosive environments.

Acquiring a Newly Tailored 2D Dion–Jacobson Hybrid Perovskite with Large Structural Distortion for Efficient Crystal Array Photodetector

AbstractDion–Jacobson (DJ) phase of 2D hybrid perovskites has recently attracted intensive attention owing to their remarkable optoelectronic properties and superior structural stability. In spite of great endeavors, only a few DJ‐type multilayered hybrid perovskites are obtained and most of them are constructed by very small organic spacer cations (e.g., Cs+ and CH3NH3+). It is still challenging to incorporate larger spacing moieties inside the perovskite cages for accomplishing excellent photoelectric properties. Herein, a newly tailored member of DJ‐type 2D perovskites, (HIS)(DMA)Pb2Br7 (1, where HIS2+ is histammonium and DMA+ is dimethylammonium), of which the perovskite cavities display a remarkable structural distortion to accommodate relatively larger secondary DMA+ cation as the “perovskitizer” is acquired. The monolayers of divalent HIS2+ organic cations directly link to inorganic sheets through NH∙∙∙Br hydrogen bonds, thus eliminating the van der Waals gap in 2D Ruddlesden–Popper counterparts and enabling superior phase stability. As a result, crystal‐based array photodetector of 1 shows fascinating photoactive activities of high detectivity (1.2 × 1013 Jones), large responsivity (18.1 A W−1), and antifatigue behavior, along with polarization‐sensitive detection based on the intrinsic anisotropy. Such findings disclose the potential of 1 for efficient photodetection, and definitely enrich the booming family of 2D hybrid perovskites.

A low-cost hole transport layer enables CsPbI2Br single-junction and tandem perovskite solar cells with record efficiencies of 17.8 % and 21.4 %

Among all-inorganic perovskites, CsPbI2Br possesses excellent intrinsic thermal stability, suitable bandgap and superior phase-stability, demonstrating large application potential for single-junction perovskite solar cells (PSCs) and perovskite/organic tandem solar cells (TSCs). To further improve the power conversion efficiencies (PCEs) of CsPbI2Br PSCs and TSCs, in this work, a dopant-free low-cost polymer PTQ10 is used as hole transport layer (HTL) for PSC and inter-connecting layer (ICL) for TSC. Owing to better energy level matching between PTQ10 and CsPbI2Br than the classic P3HT, as well as the surficial passivation of perovskite induced by the functional groups of PTQ10, the CsPbI2Br PSC with PTQ10 HTL achieves a champion PCE of 17.8 % with a high open-circuit voltage (VOC) of 1.4 V. Moreover, the ICL employing PTQ10 HTL also exhibits excellent optical and electrical properties for the application in monolithic CsPbI2Br/organic TSC. As a result, TSCs using the CsPbI2Br as the front cell and PM6:Y6 (or D18:Y6) as the rear cell present the highest PCE of 21.4 % (21.3 %), with the record high VOC of 2.22 V. This work shows the excellent performance of PTQ10 as HTL in CsPbI2Br based PSCs and TSCs and demonstrates that the development of efficient HTL is essential to further improve the performance of PSCs and TSCs.

A Novel Multiple‐Ring Aromatic Spacer Based 2D Ruddlesden–Popper CsPbI3Solar Cell with Record Efficiency Beyond 16%

AbstractTwo‐dimensional (2D) Ruddlesden–Popper (RP) CsPbI3perovskite possesses superior phase stability by introducing steric hindrance. However, due to the quantum and dielectric confinement effect, 2D structures usually exhibit large exciton binding energy, and the charge tunneling barrier across the organic interlayer is difficult to eliminate, resulting in poor charge transport and performance. Here, a multiple‐ring aromatic ammonium, 1‐naphthylamine (1‐NA) spacer is developed for 2D RP CsPbI3perovskite solar cell (PSC). Theoretical simulations and experimental characterizations demonstrate that the 2D RP CsPbI3perovskite using 1‐NA spacer with extended π‐conjugation lengths reduces the exciton binding energy and facilitates the efficient separation of excitons. In addition, its cations have a significant contribution to the conduction band, which can reduce the bandgap, promote electronic coupling between organic and inorganic layers, and improve interlayer charge transport. Importantly, the strong π–π conjugation of 1‐NA spacer can enhance intermolecular interactions and hydrogen bonding, and prepare high‐quality films with preferred vertical orientation, resulting in lower defect density, and directional charge transport. As a result, the (1‐NA)2(Cs)3Pb4I13PSC exhibits a record 16.62% performance with enhanced stability. This work provides an efficient approach to improve charge transport and device performance by developing multiple‐ring aromatic spacers.

Zirconia-based abradable coatings fabricated on single-crystal superalloy: Microstructure, residual stress and mechanical properties

Thermal sprayed ZrO2-based abradable coatings have shown great advantages in blade/shroud clearance control systems of aero-engine turbine components due to their good high-temperature stability and abradability. Dysprosia-stabilized-zirconia (DySZ) based Abradable Coating were deposited on the Ni-based single-crystal superalloy via atmospheric plasma spraying technique. Microstructure evolution behaviors of the ZrO2-based abradable coating and the substrate were examined after 1100 ℃ thermal cycling. Besides, variation of the residual stress of the top layer was measured by Raman spectroscopy. Nanoindentation tests were conducted on the polished cross-section samples to evaluate Young's modulus and hardness evolution behavior. Results indicated that the DySZ top layer exhibits superior phase stability and good thermal shock resistance during thermal cycling. Thermally Grown Oxide (TGO) layer, Inter-Diffusion Zone (IDZ), and Second Reaction Zone (SRZ) was detected with the prolongation of the heat treatment time. Correlation between the microstructure and residual stress, hardness, Young's modulus of the coating was discussed. This study aims to further understand the relationship between the coating evolution behavior and the service time.

Superior phase stability of high entropy oxide ceramic in a wide temperature range

A high entropy fluorite oxide (Hf0.2Zr0.2Ce0.2Y0.2Yb0.2)O2-δ (HEFO) was investigated to reveal its ultra-wide-temperature phase stability in air. The HEFO exhibited a single-phase fluorite structure, and its lattice constant, a, was evaluated to be 0.527 ± 0.02 nm from room temperature (RT) to > 2573 K. No precipitation of single-component oxides, such as HfO2, ZrO2, Y2O3 and CeO2, was experimentally observed. Since both Gibbs free energy (G) change of possible precipitation reactions and the second derivative of GHEFO with respect to all single-component oxides were positive, the HEFO exhibits no precipitation and decomposition at temperatures above 1700 K. The sluggish dynamics, which was verified by a long-term annealing experiment at 1473 K for 175 h showing a few Yb2O3 precipitation, contributed to the single-phase solution nature of HEFO below 1700 K. Such a superior phase stability in ultrawide temperature range help accelerate the engineering application of HEFO to be thermal structural components.

Interface Engineering Between Multi-Elemental Alloy Nanoparticles and a Carbon Support Toward Stable Catalysts.

Multi-elemental alloy (MEA) nanoparticles have recently received notable attention owing to their high activity and superior phase stability. Previous syntheses of MEA nanoparticles mainly used carbon as the support, owing to its high surface area, good electrical conductivity, and tunable defective sites. However, the interfacial stability issue, such as nanoparticle agglomeration, remains outstanding due to poor interfacial binding between MEA and carbon. Such a problem often causes performance decay when MEA nanoparticles are used as catalysts, hindering their practical applications. Herein, an interface engineering strategy is developed to synthesize MEA-oxide-carbon hierarchical catalysts, where the oxide on carbon helps disperse and stabilize the MEA nanoparticles toward superior thermal and electrochemical stability. Using several MEA compositions (PdRuRh, PtPdIrRuRh, and PdRuRhFeCoNi) and oxides (TiO2 and Cr2 O3 ) as model systems, it is shown that adding the oxide renders superior interfacial stability and therefore excellent catalytic performance. Excellent thermal stability is demonstrated under transmission electron microscopy with in situ heating up to 1023 K, as well as via long-term cycling (>370 hours) of a Li-O2 battery as a harsh electrochemical condition to challenge the catalyst stability. This work offers a new route toward constructing efficient and stable catalysts for various applications.

CO2-tolerant Sr2CoTaO6-δ double perovskite oxide as a novel cathode for intermediate-temperature solid oxide fuel cell

Sr2CoTaO6-δ (SCT) double perovskite oxide was synthesized as potential cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). We systematically characterize its phase structure, thermal stability, thermal expansion, electrical conductivity, and electrochemical performance. The SCT exhibits superior phase stability and high CO2-tolerant properties at high temperatures. The electrical conductivity of SCT is semiconductor-like and achieves its maximum value of 7 S cm-1 at 800 °C. The average thermal expansion coefficient of SCT in air is 15.0 × 10–6 K-1 in a temperature range of 30–1000 °C. The area specific resistance of SCT cathode on Gd0.1Ce0.9O1.95 (GDC) electrolyte is 0.029 Ω cm2 at 800 °C. An electrolyte-supported single cell with a thick-film GDC electrolyte (300 µm) reaches a maximum peak power density of 448 mW/cm2 at 800 °C. With high phase stability and superior electrocatalytic activity indicate that SCT is a potential novel cathode material for IT-SOFCs.

Ternary Hybrid Perovskite Solid Solution Single Crystals: Growth, Composition Determination and Phase Stability in Highly Moist Atmosphere.

Ternary hybrid perovskite solid solutions have shown superior optoelectronic properties and better stability than their ABX3 simple perovskite counterparts under ambient conditions. However, crystal growth and identification of the accurate composition of these complex crystalline compounds remain challenging, and their stability under extreme conditions such as in highly moist atmosphere is unknown. Herein, large-size (up to 2 cm) single crystals of ternary perovskite 0.80FAPbI3 ⋅ x'FAPbBr3 ⋅ y'CsPbI3 (x'+y'=0.20) are grown. An elemental analysis method based on wavelength dispersive X-ray fluorescence is proposed to determine their accurate compositions. Among these single crystals, the composition with y'=0.12 shows the best moisture stability at 90 % relative humidity for 15 days. Other components with richer or poorer Cs+ ions undergo different phase segregation behaviours. The performance and stability of photodetectors based on these single crystals are tested. This work offers a deeper insight into phase stability of ternary hybrid perovskite solid solution crystals in highly moist atmosphere.

Improved phase stability of CsPbI2Br perovskite by released microstrain toward highly efficient and stable solar cells

AbstractAll‐inorganic perovskite solar cells (PSCs) have developed rapidly in the field of photovoltaics due to their excellent thermal and light stability. However, compared with organic–inorganic hybrid perovskites, the phase instability of inorganic perovskite under humidity still remains as a critical issue that hampers the commercialization of inorganic PSCs. We originally propose in this work that microstrains between the perovskite lattices/grains play a key role in affecting the phase stability of inorganic perovskite. To this end, we innovatively design the π‐conjugated p‐type molecule bis(2‐ethylhexyl) 3,3′((4,8‐bis(5‐(2‐ethylhexyl)‐3,4‐difluorothiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)bis(3,3″‐dioctyl[2,2′:5′,2″‐terthiophene]‐5″,5‐diyl))(2E,2′E)‐bis(2‐cyanoacrylate) (BTEC‐2F) to covalent with the Pb dangling bonds in CsPbI2Br perovskite film, which significantly suppress the trap states and release the defect‐induced local stress between perovskite grains. The interplay between the microstrains and phase stability of the inorganic perovskite are scrutinized by a series of characterizations including x‐ray photoelectron spectroscopy, photoluminescence, x‐ray diffraction, scanning electron microscopy, and so forth, based on which, we conclude that weaker local stresses in the perovskite film engender superior phase stability by preventing the perovskite lattice distortion under humidity. By this rational design, PSCs based on CsPbI2Br perovskite system deliver an outstanding power conversion efficiency (PCE) up to 16.25%. The unencapsulated device also exhibits an exceptional moisture stability by retaining over 80% of the initial PCE after 500 h aging in ambient with relative humidity of (RH) 25%.image

In-situ exsolution of Ni nanoparticles to achieve an active and stable solid oxide fuel cell anode catalyst on A-site deficient La0.4Sr0.4Ti0.94Ni0.06O3-δ

(La,Sr)TiO3 has been investigated as a promising anode material for solid oxide fuel cells (SOFCs) owing to its high electronic conductivity and superior phase stability. However, the low catalytic activity of (La,Sr)TiO3 materials is a major obstacle to the application of SOFCs. Exsolution has emerged as an effective strategy to overcome the low catalytic activity of (La,Sr)TiO3 materials. In this work, Ni-doped A-site-deficient La0.4Sr0.4TiO3-δ (LST) (i.e., La0.4Sr0.4Ti0.94Ni0.06O3-δ; LSTN) with in-situ exsolved Ni nanoparticles (NPs) was developed and the effects of exsolved Ni NPs on H2 oxidation was investigated. The doped Ni was exsolved and formed NPs on the LSTN surface under reducing conditions. Owing to the high catalytic activity of the exsolved Ni NPs, the SOFC with LSTN-Ce0.9Gd0.1O2-δ (GDC) yielded a maximum power density of 0.46 W cm−2 at 850°C, 91% higher than that of the cell with LST-GDC, as well as high long-term and redox stability. Furthermore, density functional theory calculations revealed that the adsorption and dissociation of H2 were more favorable for exsolved Ni NPs than for pure Ni owing to the more positively charged surface of the exsolved Ni NPs in the LSTN. These results demonstrated that exsolution is an effective method for improving the electrocatalytic activity of perovskite (La,Sr)TiO3 materials.

All‐Inorganic Quantum‐Dot LEDs Based on a Phase‐Stabilized α‐CsPbI3 Perovskite

The all-inorganic nature of CsPbI3 perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI3 films; however, these strategies-including strain and doping-are based on organic-ligand-capped perovskites, which prevent perovskites from forming the close-packed quantum dot (QD) solids necessary to achieve high charge and thermal transport. We developed an inorganic ligand exchange that leads to CsPbI3 QD films with superior phase stability and increased thermal transport. The atomic-ligand-exchanged QD films, once mechanically coupled, exhibit improved phase stability, and we link this to distributing strain across the film. Operando measurements of the temperature of the LEDs indicate that KI-exchanged QD films exhibit increased thermal transport compared to controls that rely on organic ligands. The LEDs exhibit a maximum EQE of 23 % with an electroluminescence emission centered at 640 nm (FWHM: ≈31 nm). These red LEDs provide an operating half-lifetime of 10 h (luminance of 200 cd m-2 ) and an operating stability that is 6× higher than that of control devices.

All‐Inorganic Quantum‐Dot LEDs Based on a Phase‐Stabilized α‐CsPbI3 Perovskite

AbstractThe all‐inorganic nature of CsPbI3 perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI3 films; however, these strategies—including strain and doping—are based on organic‐ligand‐capped perovskites, which prevent perovskites from forming the close‐packed quantum dot (QD) solids necessary to achieve high charge and thermal transport. We developed an inorganic ligand exchange that leads to CsPbI3 QD films with superior phase stability and increased thermal transport. The atomic‐ligand‐exchanged QD films, once mechanically coupled, exhibit improved phase stability, and we link this to distributing strain across the film. Operando measurements of the temperature of the LEDs indicate that KI‐exchanged QD films exhibit increased thermal transport compared to controls that rely on organic ligands. The LEDs exhibit a maximum EQE of 23 % with an electroluminescence emission centered at 640 nm (FWHM: ≈31 nm). These red LEDs provide an operating half‐lifetime of 10 h (luminance of 200 cd m−2) and an operating stability that is 6× higher than that of control devices.