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Extensive studies have focused on improving the operational stability of perovskite solar cells, but few have surveyed the fundamental degradation mechanisms. One aspect overlooked in earlier works is the effect of the atmosphere on device performance during operation. Here we investigate the degradation mechanisms of perovskite solar cells operated under vacuum and under a nitrogen atmosphere using synchrotron radiation-based operando grazing-incidence X-ray scattering methods. Unlike the observations described in previous reports, we find that light-induced phase segregation, lattice shrinkage and morphology deformation occur under vacuum. Under nitrogen, only lattice shrinkage appears during the operation of solar cells, resulting in better device stability. The different behaviour under nitrogen is attributed to a larger energy barrier for lattice distortion and phase segregation. Finally, we find that the migration of excessive PbI 2 to the interface between the perovskite and the hole transport layer degrades the performance of devices under vacuum or under nitrogen. Understanding degradation mechanisms in perovskite solar cells is key to their development. Now, Guo et al. show a greater degradation of the perovskite structure and morphology for devices operated under vacuum than under nitrogen.

Extensive attention has focused on the structure optimization of perovskites, whereas rare research has mapped the structure heterogeneity within mixed hybrid perovskite films. Overlooked aspects include material and structure variations as a function of depth. These depth-dependent local structure heterogeneities dictate their long-term stabilities and efficiencies. Here, we use a nano-focused wide-angle X-ray scattering method for the mapping of film heterogeneities over several micrometers across lateral and vertical directions. The relative variations of characteristic perovskite peak positions show that the top film region bears the tensile strain. Through a texture orientation map of the perovskite (100) peak, we find that the perovskite grains deposited by sequential spray-coating grow along the vertical direction. Moreover, we investigate the moisture-induced degradation products in the perovskite film, and the underlying mechanism for its structure-dependent degradation. The moisture degradation along the lateral direction primarily initiates at the perovskite-air interface and grain boundaries. The tensile strain on the top surface has a profound influence on the moisture degradation. Understanding the correlation between moisture degradation and structural features of perovskite films is essential to improve their stability. Here, the authors apply nano-focused wide-angle X-ray scattering to map the heterogeneities over several micrometers across lateral and vertical directions.

Reducing interfacial non-radiative recombination at the perovskite/electron transport layer interface remains a critical challenge for achieving high performance and stable perovskite/silicon tandem solar cells. This study analyzes energy losses and design bilayer passivation for enhancing the performance and durability of tandem solar cells. Our experimental results confirm that, the bilayer passivation strategy, precisely modulates perovskite energy level alignment, reduces defect density, and suppresses interfacial non-radiative recombination. Moreover, the ALD-AlO x forms a homogeneous film on the perovskite grain surface while creating island-like structures at grain boundaries, enabling nanoscale local contact areas for subsequent PDAI 2 deposition. While serving as an ion diffusion barrier, this structure facilitates moderate n-type doping and enhances charge extraction and transport efficiency. Monolithic perovskite/silicon tandem solar cells incorporating AlO x /PDAI 2 treatment achieve a power conversion efficiency of 31.6% (certified at 30.8%), utilizing industrial silicon bottom cells fabricated with Q CELLS’ Q.ANTUM technology. Furthermore, our device exhibits 95% efficiency retention after 1000 hours of maximum power point tracking at 25 o C. Reducing non-radiative recombination at the perovskite/electron transport layer interface remains a critical challenge for achieving efficient perovskite/TOPCon silicon tandem solar cells. Here, authors employ bilayer passivation using AlOx/PDAI2 treatment, achieving device efficiency of 31.6%.

Temperature variations can induce phase transformations and strain in perovskite solar cells (PSCs), undermining their structural stability and device performance. Despite growing interest, the operational stability of triple-cation wide-bandgap (WBG) PSCs and tandem solar cells (TSCs) under rapid solar-thermal cycling remains poorly understood. Here, we investigate the operational stability of WBG PSCs (~1.68 eV) with a champion power conversion efficiency (PCE) of 24.31% and extend the study to TSCs. We find that degradation during device operation under rapid solar-thermal cycling (temperature change rate of 10 °C/min) is independent of passivation and occurs in two distinct regimes: an initial burn-in phase, which accounts for a rapid 60% relative loss in performance, followed by a steady degradation characterized by temperature-dependent fluctuations in photovoltaic parameters. By operando grazing-incidence wide-angle X-ray scattering and photoluminescence measurements, we reveal that temperature-induced strain, phase transition, and the increased non-radiative recombination collectively contribute to the degradation of PSCs. This work advances the understanding of the degradation mechanisms of WBG PSCs and TSCs, providing insights toward improving their operational thermal stability for real-world applications. Wide-bandgap perovskite solar cells suffer from instability under rapid thermal cycling. Here, Sun et al. investigate the degradation mechanism, showing that temperature-induced structural strain, phase transition, and increased non-radiative defects drive the degradation processes.

Nanostructured hematite (α‐Fe₂O₃) films exhibit significant potential for energy, environmental, and medical applications. In the present work, a large‐scale spray coating deposition method, scanning electron microscopy, and in situ grazing‐incidence small‐angle X‐ray scattering are combined to investigate the structure formation mechanism of pure poly(styrene)‐b‐poly(4‐vinyl pyridine) (PS‐b‐P4VP) and hybrid PS‐b‐P4VP/FeCl₃ films during and after spray deposition. Under the film deposition conditions specified in this experiment, a layered pure PS‐b‐P4VP film, a sponge‐like hybrid PS‐b‐P4VP/FeCl₃ film, and a porous α‐Fe2O3 film are obtained upon completion of the deposition. The morphological differences between the investigated pure PS‐b‐P4VP and hybrid PS‐b‐P4VP/FeCl₃ films result from the interplay among the complexation between FeCl₃ and P4VP segments, the crystallization of the P4VP segment, and the surface diffusion of the FeCl3 species. The findings of this work can offer both experimental and theoretical guidance for designing spray‐deposited block copolymer and hybrid films. The structure formation mechanism of pure poly(styrene)‐b‐poly(4‐vinyl pyridine) (PS‐b‐P4VP) and hybrid PS‐b‐P4VP/FeCl₃ films during and after spray deposition is investigated. The morphological differences result from the interplay among the complexation between FeCl₃ and P4VP segments, the crystallization of the P4VP segment, and the surface diffusion of the FeCl3 species.

Understanding the salt effects on solvation behaviors of thermoresponsive polymers is crucial for designing and optimizing responsive systems suitable for diverse environments. In this work, the effect of potassium salts (CH3COOK, KCl, KBr, KI, and KNO3) on solvation dynamics of poly(4‐(N‐(3'‐methacrylamidopropyl)‐N,N‐dimethylammonio) butane‐1‐sulfonate) (PSBP), poly(N‐isopropylmethacrylamide) (PNIPMAM), and PSBP‐b‐PNIPMAM films is investigated under saturated water and mixed water/methanol vapor via advanced in situ neutron/optical characterization techniques. These findings reveal that potassium salts enhance the films' hygroscopicity or methanol‐induced swellability. Interestingly, the anions effects do not mirror the empirical Hofmeister series, which describes the salting‐in effects for such polymers in dilute aqueous solution, particularly evident in PSBP films with an approximately inverted order. PNIPMAM and PSBP‐b‐PNIPMAM exhibit pronounced deviations from such an inverted correlation and vary somewhat for water‐rich and methanol‐rich atmospheres. Molecular dynamics (MD) simulations suggest that the observed orders of solvation result from the accessibility of the hydrated solvation shells close to the PSBP‐b‐PNIPMAM chains. The effect of potassium salts (CH3COOK, KCl, KBr, KI, and KNO3) on solvation dynamics is investigated for poly(4‐(N‐(3‐methacrylamidopropyl)‐N,N‐dimethylammonio) butane‐1‐sulfonate) (PSBP), poly(N‐isopropylmethacrylamide) (PNIPMAM), and PSBP‐b‐PNIPMAM films under saturated water and mixed water/methanol vapor via advanced in situ neutron/optical characterization techniques. The anions effects do not mirror the empirical Hofmeister series.

Ultrafine SnO2/Sn nanoparticles encapsulated into the adjustable mesoporous carbon matrix has been successfully fabricated by a facile route. The mesoporous carbon effectively improve the conductivity of the SnO2/Sn, prevent the aggregation, accommodate the strain of volume change and provide high interface area with the electrolyte, thus resulting in excellent cycling performance. A reversible capacity of 1105 mAh g–1 still retained after 290 cycles at 200 mA g–1, and the capacity still can keep at 107 mAh g–1 at high current density of 10 A g–1. The porous structures by the in situ SiOx template provide an appropriate specific surface area, which contributes to a relatively high capacitive contribution. The porous SnO2/Sn/C nanohybrids with super small SnO2 and Sn nanoparticles embedded in the porous carbon matrix was sythesized with fast photo polymerization. With the incorporation of TEOS, the size of SnO2 and Sn was inhibited around 5 nm. After SiOx, SnO and partial Sn removing, the abundant in situ generated mesoporous endow the high reversible capacity.

Continuous fast pyrolysis is developed for in situ synthesis of ultra‐small metal oxide nanoparticles embedded into three‐dimensional macroporous carbon matrix as demonstrated by the TiO2/carbon nanohybrid. The TiO2 nanoparticles with the average size of 4.6 nm ± 0.6 nm are uniformly distributed in the in situ generated macroporous carbon matrix. When evaluated as an anode in a lithium‐ion battery, the macroporous TiO2/C nanohybrid exhibits a reversible capacity of 483 mAh g–1 after 500 cycles at a current density of 67 mA g–1, which is 3.6 times higher than that of the TiO2/C calcined in a conventional batchwise way. Besides, the capacity retains 93 mAh g–1 at a high current density of 670 mA g–1. It reveals that the continuous fast pyrolysis is an efficient method to fabricate carbon composition based metal oxides as lithium‐ion battery anode materials. Continuous fast pyrolysis is utilized synthesize carbon composition based metal oxides demonstrated by TiO2/Carbon nanohybrid lithium‐ion battery anode, where better electrochemical performance in terms of reversible capacities and rate capabilities are exhibited compared to the product synthesized with the conventional batchwise calcination method due to presence of ultra‐small TiO2 nanoparticles and macroporous carbon matrix.

Titanium niobium oxide (TiNbxO2 + 2.5x) is emerging as a promising electrode material for rechargeable lithium‐ion batteries (LIBs) due to its exceptional safety characteristics, high electrochemical properties (e.g., cycling stability and rate performance), and eco‐friendliness. However, several intrinsic critical drawbacks, such as relatively low electrical conductivity, significantly hinder its practical applications. Developing reliable strategies is crucial to accelerating the practical use of TiNbxO2 + 2.5x‐based materials in LIBs, especially high‐power LIBs. Here, we provide a chronicle review of the research progress on TiNbxO2 + 2.5x‐based anodes from the early 1950s to the present, which is classified into early stage (before 2008), emerging stage (2008–2012), explosive stage (2013–2017), commercialization (2018), steady development (2018–2022), and new breakthrough stage (since 2022). In each stage, the advancements in the fundamental science and application of the TiNbxO2 + 2.5x‐based anodes are reviewed, and the corresponding developing trends of TiNbxO2 + 2.5x‐based anodes are summarized. Moreover, several future research directions to propel the practical use of TiNbxO2 + 2.5x anodes are suggested based on reviewing the history. This review is expected to pave the way for developing the fabrication and application of high‐performance TiNbxO2 + 2.5x‐based anodes for LIBs. A comprehensive chronicle review of the TiNbxO2 + 2.5x‐based anodes for lithium‐ion batteries over the last few decades has been performed, which is instructive and inspiring for the development of high‐performance TiNbxO2 + 2.5x‐based lithium‐ion batteries.