Metallic glasses are amorphous alloys produced by cooling melts quickly enough to avoid crystallization. Their disordered structures can provide high strength, a large elastic limit and soft magnetic behavior, making them useful in applications such as flexible-device hinges, energy-conversion equipment and transformer cores. Glass-forming ability is therefore important for determining the size, quality and cost of components. For more than half a century, alloy design has largely followed the eutectic rule: because eutectics melt at relatively low temperatures, they can retain a larger interval between the glass-transition and crystallization temperatures and are expected to form glasses more easily. A related criterion expresses this expectation as the reduced glass-transition temperature, Trg, the ratio of glass-transition temperature to liquidus temperature.

That rule has notable exceptions. Binary systems including zirconium–copper, hafnium–copper, titanium–copper and nickel–niobium contain compositions that outperform neighboring eutectics. Explanations based on metastable phase diagrams or eutectic-coupled zones have not been universal, and they focus mainly on which crystalline phases compete with glass formation. The new study instead asks what properties of the liquid itself make crystallization difficult. It examines Ti50Cu50, a congruent-melting alloy, and Ti27Cu73, the nearby eutectic, at the level of individual atomic clusters and the connections among them. The choice of titanium–copper is significant because extending the liquidus lines of its terminal solid solutions creates an especially clean comparison with only two simple crystalline competitors.

The experimental comparison confirmed that the eutectic was not the superior glass former. X-ray diffraction showed that Ti50Cu50 ribbons were fully amorphous after melt spinning at a wheel speed of 35 meters per second, whereas Ti27Cu73 required at least 43 meters per second to eliminate detectable crystalline peaks. Differential scanning calorimetry measured a distinct glass transition in Ti50Cu50 at 654.8 kelvin and crystallization at 683.7 kelvin, but found no distinct glass transition in the eutectic. Kissinger analysis estimated a crystallization activation energy of 376.1 kilojoules per mole for Ti50Cu50, compared with 205.3 kilojoules per mole for Ti27Cu73. These measurements establish stronger resistance to crystallization in the congruent alloy, even though its liquidus temperature was higher: 1274.3 kelvin versus 1190.9 kelvin.

To see the liquid structures directly, the team laser-heated small alloy spheres while suspending them in an aerodynamic levitator and measured them with in situ high-energy synchrotron X-ray diffraction. The experimental pair-distribution functions were then used as constraints in a newly developed energy-minimization-enhanced reverse Monte Carlo method. Unlike conventional reverse Monte Carlo reconstruction, the new method adds an energy constraint, encouraging configurations that fit the measured structure while also having low potential energy. Voronoi tessellation then divided the reconstructed three-dimensional atomic arrangements into coordination polyhedra. The researchers introduced two diversity measures, the variance in cluster fractions and Shannon entropy, alongside a new cluster-correlation variance for quantifying the strength of selective connections among local structures.

The congruent melt was not simpler than the eutectic melt. Ti50Cu50 had a more uniform distribution of cluster types, lower cluster-fraction variance and higher Shannon entropy across the measured temperature range. Its broader local environments included more Ti-centered clusters with coordination numbers between 12 and 14. In the eutectic, a few configurations dominated: Ti-centered clusters with five Ti and 12 Cu neighbors, and Cu-centered clusters with five Ti and 10 Cu neighbors. By contrast, the congruent alloy had no similarly overwhelming cluster type. Its greater Ti content also promoted stronger chemical short-range order and more unlike Ti–Cu bonds. An ideal-mixture estimate places the configurational entropy of the equiatomic composition at 0.693 times the gas constant, compared with 0.583 times that constant for the eutectic composition, providing an entropic basis for the observed diversity.

That diversity was accompanied by stronger medium-range organization. Clusters were grouped according to their degree of fivefold symmetry, and their nearest-neighbor connections were compared with those expected under random mixing. Similar clusters tended to connect, whereas groups with intermediate symmetry tended to avoid one another. In Ti50Cu50, highly fivefold-symmetric clusters formed particularly persistent connections, and the new correlation-variance measure remained consistently higher than in Ti27Cu73. A graph-theoretic analysis also found more one- and two-neighbor connections among selected icosahedral and icosahedral-like clusters. These unlike atomic bonds and cluster links lower the enthalpy of the melt, creating a stabilizing network that can impede single-atom diffusion and make structural rearrangement more collective. The study therefore interprets the better glass former as the product of competition between high configurational diversity and enthalpically favored local connections.

The advantage became stronger during the glass transition. The melts contained roughly 1,100 to 1,400 distinct cluster types, whereas the corresponding glasses contained about 600 to 800, indicating extensive structural transformation during cooling. In both alloys, many low-fivefold-symmetry clusters disappeared while highly symmetric clusters increased in abundance. Ti50Cu50 retained high-symmetry clusters particularly well: 90.2 percent of its vanished cluster types had fivefold symmetry no greater than 0.5, compared with 88.2 percent for the eutectic. Detailed reconstructions showed several routes by which lower-symmetry coordination polyhedra became icosahedral-like structures, either through distortion without a change in neighbor count or through the addition or removal of neighbors. In the glass, new connections with node degrees of two and three further strengthened the cluster network in Ti50Cu50.

The transformations reveal that a glass is not simply an unchanged snapshot of its liquid. Instead, undercooling can reorganize local motifs before they become trapped in an amorphous structure. In the congruent alloy, diverse low-symmetry clusters are preferentially converted into strongly geometrically frustrated, high-symmetry motifs. Fivefold symmetry is incompatible with periodic translational order in a crystal, and the newly formed connections make it difficult for atomic groups to rearrange into a crystalline embryo. Cluster diversity thus creates geometric frustration, while correlated connections stabilize the resulting network and raise the energetic cost of crystallization. The findings do not imply that icosahedral order is unimportant: the eutectic melt actually contained more such clusters, yet it still formed glass less readily. The decisive feature was not the presence of icosahedral motifs alone, but their integration into a diverse and persistent structural network.

A reverse comparison with nickel–niobium supported the proposed rule. In that system, the eutectic Ni58.5Nb41.5 is the better glass former, while congruent Ni75Nb25 is not. When the same structural measures were applied to their melts, the eutectic liquid was the more complex one, showing higher Shannon entropy, lower cluster-fraction variance and stronger inter-cluster correlations. Across two systems with opposite relationships between phase-diagram position and glass formation, the better glass former was consistently the composition whose melt displayed greater structural diversity and connectivity. The study therefore suggests that alloy designers could search for compositions that create complex liquids, including certain congruently melting intermetallics, rather than relying exclusively on eutectic minima or maximizing icosahedral order. The evidence is mechanistic and model-based, however: the principal experiments concerned binary titanium–copper alloys, while the broader nickel–niobium calculations support generality but do not establish performance for every alloy family.

Subject of Research: Atomic melt structure and anomalous glass-forming ability in titanium–copper and nickel–niobium alloys

Article Title: To Be or Not to Be Eutectic: Anomalous Glass Forming Ability Governed by Melt Structural Complexity

Article References: Chen, W., Wei, X., Wang, C., Lu, Z., Zhang, F., Huang, Y., Zhang, Y., Wang, L., Cao, S., Zhou, C., Yang, K., Fu, Z., Zhao, J., Sun, D., Meng, F., Zhou, Z., Wang, X.-L., Wang, W., & Ma, D. (2026). To Be or Not to Be Eutectic: Anomalous Glass Forming Ability Governed by Melt Structural Complexity. Advanced Science, Article e78359. https://doi.org/10.1002/advs.78359

Image Credits: AI Generated

DOI: 10.1002/advs.78359

Keywords: metallic glasses, glass-forming ability, melt structure, titanium–copper, cluster diversity, cluster correlations, atomic ordering, crystallization kinetics, synchrotron diffraction, inverse design, Eutectic, Anomalous

To appreciate why the timing of additive delivery matters, it helps to understand what makes mixed-halide perovskites both brilliant and brittle. Perovskites are crystalline materials built from a framework of lead and halide ions, typically iodide and bromide in red-emitting compositions, interspersed with organic or inorganic cations. By blending halides, engineers can tune the bandgap and therefore the emission color with remarkable precision. But that same blend is the source of the material’s Achilles heel. Under the electric field inside a working LED, halide ions migrate through the crystal lattice, segregating into iodide-rich and bromide-rich domains. The emission color drifts during operation, a phenomenon that has plagued spectrally stable mixed-halide devices for years. At the same time, defects, uncoordinated lead atoms, missing halides, and disordered grain boundaries, act as traps where injected electrons and holes recombine without emitting a single photon, draining efficiency.

The conventional response has been additive engineering: sprinkle passivating molecules into the precursor solution and hope they find their targets. The problem, as the new work makes clear, is that a perovskite film does not form all at once. It crystallizes in stages, from nucleation through grain growth to final film consolidation, and an additive introduced into the precursor is present from the very beginning whether it is needed there or not. A molecule that is ideal for patching grain boundaries late in the process may instead interfere with early nucleation if it is present from the start. Shao and Yang’s insight was to treat film formation as a choreography rather than a single event, matching each additive to the stage where it can do the most good.

The first additive, 4-vinylbenzylammonium iodide, or VBAI, goes into the precursor solution itself. As an ammonium salt, it belongs to a family of molecules well known in the perovskite community for defect passivation. The ammonium group can hydrogen-bond with the perovskite framework, while the iodide counterion helps replenish halide vacancies, one of the most damaging defect types in these materials. The vinylbenzyl portion adds a bulky aromatic character that can help anchor the molecule at the perovskite surface and, in principle, stiffen the lattice against ion migration. By placing VBAI in the precursor, the researchers ensure it is incorporated during crystallization, where it can influence grain growth and passivate defects as they form rather than after the fact.

The second additive, octylphosphonic acid, or OPA, takes a different route entirely: it is dissolved into the antisolvent, the liquid dripped onto the spinning precursor film to trigger rapid crystallization. Phosphonic acids carry a distinctive dual personality. The phosphonic acid head is a strong Lewis base that coordinates to undercoordinated lead atoms at the perovskite surface, neutralizing deep traps that would otherwise swallow charge carriers. The long octyl chain, meanwhile, is hydrophobic and insulating, and previous work has shown that octylphosphonate species can self-assemble into robust hydrogen-bonded networks that wrap around perovskite grains, shielding them from moisture and thermal stress. Delivering OPA through the antisolvent means it arrives precisely at the moment the film is solidifying, positioning it at surfaces and grain boundaries where its protective chemistry is most valuable, without contaminating the early nucleation chemistry.

The complementary division of labor between the two additives is the conceptual heart of the paper. VBAI, present from the start, shapes the crystal growth itself; OPA, arriving with the antisolvent, seals and protects the finished grains. Combined experimental characterization and density functional theory calculations, performed with the widely used plane-wave codes developed by Kresse and Furthmüller, support this picture. The dual-additive films show improved morphology and crystallinity, meaning larger, better-ordered grains with fewer boundaries where ions could hop and traps could lurk. The measured trap density drops, and with it the rate of non-radiative recombination, the silent efficiency killer in every LED. The films also hold up better against heat and resist the spectral drift that normally afflicts mixed-halide emitters under sustained operation.

The device numbers translate the materials science into something display engineers and optoelectronics researchers can actually use. The optimized deep-red PeLEDs emit at an electroluminescence peak of 734 nanometers, squarely in the deep-red region where perovskite performance has historically lagged behind green and red-emitting cadmium-based and organic alternatives. The maximum external quantum efficiency of 21.70 percent means that more than one in five electrons injected into the device emerges as a useful photon, a figure that places these diodes among the more efficient deep-red perovskite emitters reported to date. Just as important for any practical application, the operational lifetime, quantified as T50, the time for brightness to fall to half its initial value, reaches 26.39 hours. For a device class where spectral instability and rapid degradation have often limited lifetimes to minutes or a few hours, that is a meaningful step forward, even if it remains far from the tens of thousands of hours demanded of commercial display panels.

The strategy also fits into a broader and rapidly maturing research landscape. The paper’s reference list reads like a map of the field’s recent trajectory: Nature Photonics work on interfacial reactions for bright and stable deep-red devices, Advanced Materials reports on space-confined fabrication of cesium lead iodide nanocrystal films and lateral zero-dimensional/three-dimensional heterostructures, and a growing literature on dual-additive and dual-site strategies borrowed from perovskite solar cell research. Ammonium salts have been shown in multiple studies to passivate different defect types selectively, and phosphonic acid modifiers have already proven their worth in blue perovskite LEDs and high-efficiency solar cells. What Shao and Yang add to this conversation is the stage-dependent logic, the recognition that where and when an additive enters the process can matter as much as which molecule you choose. That principle is transferable: the same reasoning could guide additive selection for blue and green perovskite emitters, for wide-bandgap compositions in tandem solar cells, and for any application where crystallization kinetics and defect chemistry must be tamed simultaneously.

Caveats remain, as they always do on the road from laboratory record to living-room screen. The T50 lifetime of roughly 26 hours was measured under the specific operating conditions of the study, and translating such results to the higher brightness and harsher duty cycles of commercial displays will require further gains in encapsulation, thermal management, and ion-migration suppression. Lead toxicity continues to shadow the entire perovskite field, motivating parallel work on lead-free compositions and on recycling strategies. Still, the study demonstrates that some of the perovskite LED’s most stubborn problems, defect-assisted recombination, halide segregation, and thermal degradation, can be attacked with nothing more exotic than two well-chosen small molecules added at the right moments in a standard solution-processing workflow. No new deposition equipment, no high-temperature steps, no rare-earth chemistry. If the stage-dependent additive philosophy proves as general as the authors suggest, the humble antisolvent drip may turn out to be one of the most powerful levers in perovskite engineering, and deep-red perovskite LEDs may finally be on a credible path from the optics bench to the display stack.

Subject of Research: Stage-dependent dual-additive engineering of mixed-halide perovskite films for efficient and stable deep-red light-emitting diodes

Article Title: Efficient and stable deep-red mixed-halide perovskite LEDs via dual-additive engineering

Article References: Shao, Y., & Yang, J. (2026). Efficient and stable deep-red mixed-halide perovskite LEDs via dual-additive engineering. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13948-6

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13948-6

Keywords: perovskite LEDs, deep-red emission, mixed-halide perovskites, additive engineering, defect passivation, ion migration, VBAI, octylphosphonic acid, external quantum efficiency, spectral stability, crystallization kinetics, optoelectronics

The review’s central argument is deceptively simple: clinical success is not determined by how high a formulation can push drug concentration, but by how long it can keep that concentration alive during gastrointestinal transit. Supersaturation is a kinetic phenomenon, not a thermodynamic one. The moment a drug is dissolved above its equilibrium solubility, the system is primed to return to a stable state through nucleation, crystal growth, or phase separation. The formulation scientist’s real task is therefore not to create supersaturation — that is relatively easy — but to control the kinetics of its generation, maintenance, and eventual dissipation long enough for absorption to occur in the small intestine.

The authors analyze three platforms that achieve this goal through fundamentally different mechanisms. Pharmaceutical cocrystals are crystalline multicomponent systems in which a drug molecule is locked into a lattice with a coformer, typically a benign molecule such as saccharin, nicotinamide, or an amino acid. When the cocrystal dissolves, both components enter solution simultaneously, and the drug’s apparent solubility is governed by the solubility product of the cocrystal and the solution complexation between drug and coformer. Because the coformer concentration can be orders of magnitude higher than the drug’s, the drug is driven into a supersaturated state that can far exceed the solubility of the parent crystalline form — the so-called solubility advantage.

Amorphous solid dispersions, or ASDs, take the opposite route: they destroy the crystal lattice entirely. The drug is molecularly dispersed in a polymeric carrier — hydroxypropyl methylcellulose acetate succinate (HPMCAS), polyvinylpyrrolidone (PVP), or the copolymer PVPVA are the workhorses — typically by hot-melt extrusion or spray drying. The amorphous drug has a higher free energy than its crystalline counterpart, and this excess free energy translates directly into a higher apparent solubility. During dissolution, the polymer dissolves alongside the drug and, ideally, releases it in a congruent manner, then acts as a crystallization inhibitor in solution by adsorbing to nascent crystal surfaces, disrupting nucleation, and raising the kinetic barrier to precipitation.

Co-amorphous systems represent a third strategy that dispenses with polymers altogether. Here, the drug is co-amorphized with a second small molecule — another drug, an amino acid, or a salt coformer — through mechanochemical grinding or spray drying. The partner molecule serves two roles at once: it raises the glass transition temperature of the mixture, suppressing molecular mobility and physical instability, and it forms specific intermolecular interactions, often hydrogen bonds or ionic pairs, that stabilize the amorphous drug at the molecular level. Because the coformer is a small molecule, drug loading can be far higher than in polymer-based dispersions, an attractive property for high-dose compounds.

Where the review becomes genuinely provocative is in its taxonomy of failure modes. The authors catalog how each platform dies, and the mechanisms are strikingly platform-specific. Cocrystals are vulnerable to pH-triggered solubility collapse: because cocrystal solubility depends on the ionization states of both drug and coformer, a cocrystal that performs brilliantly in gastric fluid can crash out of solution upon entering the higher-pH environment of the intestine. Solution-mediated phase transformation is another killer — the cocrystal can convert in situ to the less-soluble parent drug crystal, silently erasing the solubility advantage. Incongruent saturation, where the coformer and drug dissolve at mismatched rates, further destabilizes the system.

ASDs fail in different ways. Premature crystallization during storage or dissolution remains the classic concern, but the review highlights subtler mechanisms that have emerged from recent work at Purdue and elsewhere. Liquid–liquid phase separation (LLPS), in which a supersaturated solution splits into a drug-rich nanodroplet phase and a drug-poor continuous phase, can be either a blessing or a curse: drug-rich droplets may actually enhance membrane transport, but uncontrolled phase separation can sequester drug in forms that crystallize rapidly. Moisture is a persistent enemy — sorbed water plasticizes the amorphous matrix, lowers the glass transition temperature, and can trigger moisture-induced amorphous–amorphous phase separation, in which drug and polymer demix at the molecular scale long before any crystal appears. Even hydrogen bonding, usually celebrated as the stabilizing force between drug and polymer, has been identified as a failure mechanism: overly strong drug–polymer interactions can retard polymer dissolution and trap drug at the dissolving surface, sabotaging release.

Co-amorphous systems bring their own pathologies. Because they lack a polymeric inhibitor, they rely entirely on the coformer for stabilization, and aging during storage can alter dissolution performance in either direction — some systems lose dissolution over time without ever recrystallizing, a phenomenon the review notes is often overlooked in accelerated stability studies that focus solely on crystallization. The choice of coformer is critical: amino acids with high glass transition temperatures can dramatically stabilize a fragile drug, while poorly matched partners can leave the mixture more mobile than either component alone.

The unifying framework the authors propose rests on thermodynamic activity rather than concentration. What drives passive membrane transport is not the total dissolved drug but the drug’s chemical potential — its thermodynamic activity — in the unstirred water layer adjacent to the intestinal epithelium. A supersaturated solution at modest concentration but high activity can outperform a nominally more concentrated but phase-separated system. This reframing explains why simply maximizing supersaturation ratio is a flawed design goal: pushing activity too high accelerates nucleation and LLPS, shortening the very lifetime of the supersaturated state that absorption depends on. The optimal formulation occupies a kinetic sweet spot in which supersaturation is generated fast enough to matter, sustained long enough to be absorbed, and dissipated slowly enough to avoid a precipitation cliff.

The review’s expert opinion points toward predictive, mechanism-driven formulation design as the field’s next frontier. Physiologically based pharmacokinetic modeling, biorelevant dissolution testing that captures pH transitions and bile salt solubilization, and molecular-level screening of drug–polymer and drug–coformer compatibility are converging on the ability to forecast failure before a formulation reaches the clinic. For an industry in which a large fraction of pipeline molecules are classified as poorly soluble, the message is clear: the future of oral drug delivery belongs not to the formulations that generate the highest supersaturation, but to those that understand — and control — the dynamics of its decay.

Subject of Research: Supersaturation dynamics and failure mechanisms in cocrystals, amorphous solid dispersions, and co-amorphous drug delivery systems

Article Title: Supersaturation dynamics of cocrystals, amorphous solid dispersions and co-amorphous systems: generation mechanisms, stability considerations, and basis of failure modes

Article References: Albarazi, N., Alzyoud, A., Ahmed, I. S., Elkhabaz, A., Hwang, S.-J., & Alhalaweh, A. (2026). Supersaturation dynamics of cocrystals, amorphous solid dispersions and co-amorphous systems: generation mechanisms, stability considerations, and basis of failure modes. Journal of Pharmaceutical Investigation. https://doi.org/10.1007/s40005-026-00827-0

Image Credits: AI Generated

DOI: 10.1007/s40005-026-00827-0

Keywords: supersaturation, cocrystals, amorphous solid dispersions, co-amorphous systems, liquid-liquid phase separation, oral bioavailability, crystallization kinetics, poorly soluble drugs, glass transition temperature, HPMCAS, solution-mediated phase transformation, drug delivery

The importance of nickel oxide in inverted, or p-i-n, perovskite solar cells is difficult to overstate. In this architecture, the light-absorbing perovskite layer sits atop a hole-transporting layer, and every photon-generated hole must pass cleanly through that buried interface before it can be collected. Nickel oxide is prized for its chemical stability, wide bandgap, deep valence band and low cost, but depositing it uniformly over large areas has always involved a painful trade-off. Solution-based chemical bath deposition can cover large, even textured substrates conformally, but the rapid, disorderly hydrolysis of nickel salts tends to produce films riddled with pinholes and aggregates. Vacuum techniques such as sputtering or atomic layer deposition offer denser films but are slower, more expensive and harder to marry with high-throughput manufacturing.

The Nankai-led team attacked the problem at the level of crystallization kinetics rather than after the fact. Their insight was to introduce potassium tartrate, a ligand that binds nickel ions into exceptionally stable coordination complexes in the deposition bath. By sequestering a fraction of the free nickel ions, the ligand suppresses the chaotic, uncontrolled aggregation that normally plagues chemical bath growth and halves the hydrolysis rate constant, slowing it to 0.124 liters per mole per minute. That seemingly modest number is the heart of the result: slower, more orderly crystallization gives the film time to nucleate evenly across the substrate and to grow into a dense, continuous layer rather than a patchwork of islands and voids.

The kinetic control pays off in a striking way at the nanoscale. The resulting films are composed of remarkably refined crystallites measuring just 4.8 nanometers. For most materials, smaller grains would sound like a disadvantage, but here the fine nanostructure is precisely the point. Shrinking the crystallites maximizes the density of grain boundaries reaching the surface, and each boundary terminates in hydroxyl groups. These hydroxyl terminations serve as robust chemical anchoring sites for self-assembled monolayers, the carbazole-based phosphonic acid molecules that have become the workhorses of modern perovskite photovoltaics. A denser carpet of anchoring sites allows the monolayer to form a chemically cohesive, defect-suppressed buried interface, where charge extraction is fast and non-radiative recombination is minimized.

The team backed this picture with extensive interfacial characterization and charge-carrier dynamics measurements on nickel oxide monolayer stacks, supported by density functional theory calculations and molecular dynamics simulations that probed the coordination chemistry and the energetics of monolayer attachment. The calculations and experiments together paint a consistent story: the potassium tartrate-regulated surface is not merely smoother, it is chemically better matched to the self-assembled monolayer, so the molecules graft uniformly instead of clustering on reactive patches. Fewer clustered molecules means fewer shunting pathways and fewer deep traps, which translates directly into higher open-circuit voltage and fill factor.

The device numbers speak for themselves. Champion inverted cells built on the treated nickel oxide reached a power conversion efficiency of 27.40 percent, and an independent certified measurement returned a reverse-scan efficiency of 27.35 percent, placing these single-junction cells among the very best inverted devices ever reported. More importantly for commercialization, the advantage survived scale-up. A 17.7-square-centimeter mini-module achieved 23.42 percent efficiency, and a substantially larger 81.5-square-centimeter module still delivered 21.97 percent. In the perovskite field, where efficiency typically collapses as area grows because coating non-uniformities and interconnect losses compound, retaining better than 22 percent on a module the size of a postcard is a genuine milestone.

Efficiency alone, however, has never been the sole barrier to market entry. Stability under continuous illumination and heat has haunted perovskite devices since their inception, and the buried interface is one of the most common sites of degradation, where ion migration and interfacial reactions quietly erode performance. Here too the coordination-regulated films excelled. Small-area devices retained 90 percent of their initial efficiency after 2,656 hours of operation, and the 17.7-square-centimeter mini-modules held more than 90 percent of their initial performance after 1,200 hours under the demanding ISOS-L-1I protocol, an internationally recognized stress test combining continuous illumination with elevated temperature and electrical bias. Such endurance figures suggest that the defect-suppressed buried interface is not just a transient efficiency boost but a structural improvement in device physics.

What makes the result particularly compelling from a manufacturing standpoint is that the underlying technique is inherently scalable. Chemical bath deposition is a low-temperature, low-cost, solution-based process that requires no vacuum equipment and can, in principle, coat substrates of arbitrary size and shape, including textured surfaces that evaporative methods struggle to cover. By solving the coverage-versus-reactivity trade-off inside the bath chemistry itself, the researchers have essentially upgraded the method from a laboratory curiosity to a credible industrial candidate. The approach is compatible with subsequent self-assembled monolayer deposition and standard perovskite coating steps, meaning it slots into existing p-i-n fabrication flows without requiring an architectural rethink.

The work also carries a broader lesson for the field. Much of the recent progress in perovskite photovoltaics has come from interfacial engineering, and the Nankai study demonstrates that the substrate beneath a self-assembled monolayer is not a passive bystander but an active determinant of how well that monolayer performs. Controlling the crystallization kinetics of the inorganic layer, right down to the density of surface hydroxyl groups, is a form of interface design that operates one level deeper than most molecular engineering campaigns. It hints that similar coordination-regulated strategies could improve other metal oxide transport layers, from tin oxide electron contacts to zinc-based alternatives, across both single-junction and tandem devices.

Challenges remain before perovskite modules based on this chemistry can leave the laboratory for the factory floor. Scaling from 81.5 square centimeters to full-sized panels will require maintaining the same kinetic control across even larger baths and faster throughput, and long-term field testing beyond accelerated laboratory protocols will be essential. Lead content, encapsulation and recycling logistics also loom over the entire perovskite enterprise. But by demonstrating certified 27.35 percent cell efficiency, 23.42 percent module efficiency and more than a thousand hours of stable module operation from a single, industrially friendly deposition process, the team has decisively narrowed the gap between what perovskites can do in principle and what they can do in production. The sun delivers more energy to Earth in an hour than humanity uses in a year; chemistry like this brings the devices needed to harvest it one large step closer to being cheap, durable and genuinely scalable.

Subject of Research: Coordination-regulated chemical bath deposition of conformal nickel oxide hole-selective layers for efficient and stable perovskite solar modules

Article Title: Scalable and conformal nickel oxide for efficient perovskite solar modules

Article References: Yang, H., Wang, Y., Li, H., Wu, Y., Li, S., Han, X., Wang, D., Ding, Z., Han, Y., Zheng, Q., Chen, L., Du, Z., Alshahrani, T., Chen, C., Wang, X.-Y., Jiang, Y., & Yuan, M. (2026). Scalable and conformal nickel oxide for efficient perovskite solar modules. Nature Photonics. https://doi.org/10.1038/s41566-026-02012-z

Image Credits: AI Generated

DOI: 10.1038/s41566-026-02012-z

Keywords: perovskite solar cells, nickel oxide, chemical bath deposition, self-assembled monolayers, hole transport layer, power conversion efficiency, solar modules, crystallization kinetics, buried interface, photovoltaic stability, potassium tartrate coordination, ISOS-L-1I protocol

The crystallization of a glass is a phase transformation of intense interest to materials scientists because it determines the thermal stability of amorphous materials used in phase-change memory devices, optical fibers, infrared optics, and solar cells. When a glass is held at a fixed temperature above its glass transition, tiny crystal nuclei form and grow until the entire sample has crystallized. The classical framework for describing this process is the Kolmogorov–Johnson–Mehl–Avrami (KJMA) model, which relates the fraction of material transformed at any moment, denoted α, to an exponential function of time raised to a power known as the Avrami exponent n, multiplied by a temperature-dependent rate constant k. According to the model, the transformed fraction follows α = 1 − exp(−(kt)^n), where k itself obeys Arrhenius behavior, k = A exp(−E/RT), with E the activation energy, A the Arrhenius prefactor, R the gas constant, and T the absolute temperature.

Traditionally, experimentalists determine these parameters by converting the raw DSC heat-flow signal into the extent of conversion as a function of time and then constructing double-logarithmic plots of ln[−ln(1 − α)] against ln t. This procedure, while effective, requires accurate knowledge of the moment at which crystallization begins—an assignment notoriously prone to error in isothermal experiments, where the sample takes time to equilibrate after being plunged into the hot furnace of the calorimeter. As Elabbar and Abu-Sehly emphasize, drawing on earlier insights from Waters and Paddy as well as Brown and Galwey, the relevant kinetic parameters can instead be derived directly from the shape of the DSC curve itself, sidestepping the conversion analysis entirely and potentially reducing experimental and numerical uncertainty.

The mathematical basis of the direct method is elegant. The DSC signal φ is proportional to the rate of transformation, φ = ΔHc·(dα/dt), where ΔHc is the total enthalpy released during crystallization, obtained from the area under the peak. Differentiating the KJMA expression yields a curve with a characteristic maximum at a time tmax given by tmax = (1/k)·[((n − 1)/n)]^(1/n). The height of the peak at that moment, φmax, combined with tmax and ΔHc, satisfies a simple relation involving only the Avrami exponent n. Thus, by measuring just the peak time, the peak height, and the total heat of crystallization, the researcher can solve for n, then back-substitute to obtain the rate constant k at each crystallization temperature. The method has one well-defined limitation: it does not apply to first-order reactions with n = 1, for which the DSC curve has no maximum.

Activation energy can likewise be obtained without conversion data. One route, developed previously by Elabbar and known as the Δt-method, uses the full width at half maximum of the crystallization peak. Plotting the natural logarithm of this width, Δt, against the reciprocal of the crystallization temperature Tc produces a straight line whose slope equals E/R. A second, newly demonstrated route exploits the position of the peak itself: because the half-crystallization time t1/2 of the conversion curve is closely related to tmax of the DSC peak, plotting ln tmax against 1/Tc also yields a straight line with slope E/R. Both approaches rely solely on geometric features of the calorimetric traces, making them insensitive to many of the ambiguities that plague conversion-based analyses.

To test the framework, the team prepared glassy In10Se90 by the melt-quenching technique. High-purity selenium and indium, each of five-nines purity, were sealed in evacuated quartz ampoules, heated to 950 °C for 24 hours with frequent rotation to ensure homogenization, and then rapidly quenched in water. Isothermal DSC measurements were performed on a TA Q2000 calorimeter under dry nitrogen, calibrated with indium standards, with a fixed 5-milligram sample mass. Crucially, the samples underwent a rejuvenation heat treatment to erase physical aging effects, ensuring that the crystallization kinetics reflected the intrinsic material rather than a history-dependent relaxation state.

The measurements delivered strikingly consistent numbers. For In10Se90 glass, the Δt-method gave an activation energy of 112 kJ/mol, a value widely reported in the literature for this composition. The new tmax method yielded 142 kJ/mol, while an Arrhenius plot of the directly determined rate constants gave E = 136 kJ/mol and an Arrhenius prefactor A of 3.22 × 10^16 s⁻¹. The Avrami exponent calculated from the peak analysis came out at approximately 2 across the crystallization temperatures studied. For the validation case of Sb10Se90, using data from an earlier study, the tmax method produced an activation energy of 98.9 kJ/mol, in excellent agreement with the 106 kJ/mol obtained by the Δt-method, while the Arrhenius treatment of the rate constants gave E = 105.6 kJ/mol and A = 4.81 × 10^11 s⁻¹—tight mutual confirmation across independent routes.

Beyond the numbers, the Avrami exponents reveal a fascinating physical story about how these two glasses crystallize. In In10Se90, an exponent near 2 points to a constrained growth mode—either one-dimensional growth with continuous nucleation or two-dimensional growth with a decreasing or limited nucleation rate—suggesting heterogeneous nucleation sites and anisotropic extension of crystalline domains within the amorphous matrix. In Sb10Se90, by contrast, an exponent near 3 signals three-dimensional, volumetric crystal growth proceeding uniformly through the bulk, under either constant nucleation or site-saturated nucleation. The substitution of antimony for indium thus fundamentally alters the geometry of the transformation, information that the direct DSC analysis captures with no additional experimental effort.

The authors note that the slightly different activation energies obtained from the different routes likely stem from an experimental artifact: the difficulty of assigning the true starting time t = 0 in isothermal DSC traces. The Δt-method is immune to this uncertainty because peak width, unlike peak position, does not depend on the choice of time zero, which is why the team argues it provides the most accurate estimates of E. Their conclusion that Δt-derived values agree best with the extensive literature supports this interpretation and offers practical guidance for anyone analyzing isothermal calorimetry data.

The broader significance of the work lies in accessibility. Isothermal DSC instruments are ubiquitous in materials laboratories, and the new method transforms what was once a multi-step fitting exercise into a set of straightforward measurements on the raw thermal traces—peak time, peak height, peak width, and total heat. For researchers designing chalcogenide glasses for phase-change memory, optical storage, or thermoelectric applications, this means faster, more reproducible characterization of thermal stability and crystallization behavior. It also reinforces a lesson that resonates across thermal analysis: sometimes the richest information about a material’s inner transformation is sitting in plain sight, in the very shape of the curve the instrument draws.

Subject of Research: Direct determination of crystallization kinetic parameters from isothermal DSC curves of chalcogenide glasses using the KJMA model

Article Title: Determination of the kinetic parameters for crystallization directly from isothermal DSC curves

Article References: Elabbar, A. A., & Abu-Sehly, A.-H. A. (2026). Determination of the kinetic parameters for crystallization directly from isothermal DSC curves. Discover Chemistry, 3(1), Article 503. https://doi.org/10.1007/s44371-026-00960-7

Image Credits: AI Generated

DOI: 10.1007/s44371-026-00960-7

Keywords: crystallization kinetics, differential scanning calorimetry, chalcogenide glasses, KJMA model, Avrami exponent, activation energy, isothermal DSC, thermal analysis, glass transition, In10Se90, Sb10Se90, Arrhenius equation