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Enhancing the Phase Stability of Inorganic α-CsPbI <sub/>3</sub> by the Bication-Conjugated Organic Molecule for Efficient Perovskite Solar Cells
摘要： Inorganic CsPbI3 perovskite has demonstrated promising potentials for photovoltaic applications, whereas the black perovskite polymorph (α phase) of CsPbI3 was easily prone to converting into yellow phase (δ phase) under ambient moist environment, which restrained its practical application and further studies severely. In this study, p-phenylenediammonium iodide (PPDI) was employed to posttreat CsPbI3 films for controlling the phase conversion, strengthening moisture resistance, and improving device performance. The multiple roles of PPDI were as follows: (1) avoiding spontaneous octahedral tilting by ionic bonds between NH3+ of PPD2+ and I? of [PbI6]4?; (2) enhancing the hydrophobicity induced by exactly exposed oil-wet (hydrophobic) benzene rings; and (3) passivating surface defects and filling I vacancies. As a result, after the treatment, mutable a-CsPbI3 could maintain its α phase for at least 30 d in dry air (<20% RH). The perovskite solar cells with PPDI treatment exhibited reproductive photovoltaic performance with a champion power conversion efficiency (PCE) of 10.4, and 91% of the initial PCE was retained after storage for 504 h in a dark dry box without any encapsulation.
关键词： solar cells,CsPbI3,posttreatment method,phase stability,inorganic perovskite
更新于2025-09-16 10:30:52
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Behavior of yttria-stabilized zirconia (YSZ) during Laser Direct Energy Deposition of an Inconel 625-YSZ Cermet
摘要： Thermal barrier coatings (TBC) are regularly used today to protect and extend the service life of several superalloys which are extensively used in high temperature applications. The existing TBCs are typically between 0.1 to 0.5 mm in thickness, are deposited on metal substrates using plasma spray or electron beam vapor deposition, and can reduce temperatures at the substrate surface by up to 300 °C. For greater temperature reductions there is a need for thicker TBCs. The building of thick TBCs has to date been stymied by poor adhesion, and cracking during deposition. It has been suggested that a functionally graded approach may reduce the residual stresses which result in these defects. To date there have been few reports on the deposition of ceramic or cermet coatings using laser AM and none have reported on the phase stability of ceramic particles post-deposition. This paper is a first report on the phase stability of ceramic particles following the compositional segregation of elements during deposition using a powder feed additive manufacturing process. Functionally graded (FG), thick TBCs (>3 mm) consisting of Inconel 625 (IN625) and yttria-partially stabilized zirconia (8YSZ) were deposited on an A516 steel substrate via laser direct energy deposition (LDED). Good interfaces were observed between the bond coat (BC) and first cermet layer and between the graded cermet layers. In cermet layers that did exhibit good interfaces, fine, re-solidified, YSZ particles were homogeneously distributed within the Inconel 625 matrix. The YSZ particles exhibited a tetragonal lattice structure and were depleted of yttrium. In contrast, the thin YSZ layer formed on a cermet surface showed no yttrium depletion.
关键词： compositional stability,thick thermal barrier coatings,Multi-material additive manufacturing,functionally graded materials,ceramic additive manufacturing,phase stability of YSZ
更新于2025-09-12 10:27:22
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Chemical Composition and Phase Evolution in DMAI-Derived Inorganic Perovskite Solar Cells
摘要： Cesium based inorganic perovskite CsPbI3 solar cells have attracted arising research interests due to its improved thermal stability and reduced ion immigration in comparison with their organic-inorganic counterparts. However, the preferred black perovskite CsPbI3 is thermodynamically unstable at room temperature, and it will spontaneously transform to the undesired non-photoactive yellow phase. The essence of the phase instability is the small size of Cs cation, which is not suitable to support the three-dimensional PbI3- framework. The large lattice strain induced from the ion size mismatch will drive the CsPbI3 lattice structure from three dimensional (3D) perovskite phases to one dimensional (1D) non-perovskite phase. Therefore, the improvement of the lattice symmetry and reduction of the lattice strain are the two directions to dissolve the problem of phase instability. The nanocrystal-induced phase stabilization is one strategy to reduce the lattice strain by increasing the surface area of the crystals in the film, which is normally realized by introducing organic long-chain alkyl amine in the precursor solution. The shortcoming of this method is its negative effect of a large number of grain boundaries on the carrier transport and injection. Currently, the most widely used and effective strategies are the DMAI related methods, including the DMAI additive methods and the HI derived methods. The HI derived methods, normally named HI additive, HI?PbI2 or HPbI3 precursor, are demonstrated inevitably bring the DMA byproduct in the precursor solution from the reaction between HI and DMF. Although there are already several works focused on the elaboration of the final perovskite layer with the pure inorganic phase or still the organic-inorganic composite, the conclusion is still a huge controversy. Therefore, whether the organic DMA cation exists, how much the organic DMA cation in the crystal lattice, the properties of the DMA/Cs mixed perovskite phase and the mechanism of the DMAI-assisted formation of the Cs base perovskite thin film are still unclear. In this work, we tracked the chemical composition, phase and bandgap of the perovskite layer during the thermal treatment. It was found that, with a controlled thermal annealing process, a more thermodynamically stable perovskite of mixed cation DMA0.15Cs0.85PbI3 could form with a certain amount of Cs4PbI6 residue. Unlike other mixed cation perovskite materials, the composition of DMA/Cs mixed perovskite is well fixed instead of a continuous component distribution. Further thermal annealing transformed the film into C(cid:26)(cid:4)(cid:14)(cid:18)/(cid:25)3 and then into D(cid:26)(cid:4)(cid:14)(cid:18)/(cid:25)3. The DMA0.15Cs0.85PbI3 phase exhibits a more symmetrical structure, a narrower bandgap, and superior phase stability than that of C(cid:26)(cid:4)(cid:14)(cid:18)/(cid:25)3. These findings will benefit the in-depth understanding of the properties of inorganic perovskite and their phase stability issue.
关键词： DMAI,inorganic perovskite,CsPbI3,phase stability,solar cells
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Measurement of Inter-Sweep Phase Stability of an FDML Laser with a 10 kHz Tunable Ring Laser
摘要： Fourier Domain Mode Locking (FDML) lasers are light sources that generate a sequence of narrowband optical frequency sweeps at the fundamental or harmonic of the cavity repetition rate [1]. This frequency swept output can also be considered as a sequence of strongly chirped, long pulses. FDML lasers are mainly used in swept source optical coherence tomography (SS-OCT), a medical imaging technique. The coherence length of the source, i.e. the intra-sweep phase stability of an FDML sweep, is decisive for the image quality and performance of OCT imaging [2]. We present the ?rst measurement of the inter-sweep phase of an FDML laser, i.e. the phase relation of consecutive sweeps. For this we measured the beating of an FDML laser with a ring laser having a line width of less than 10 kHz. The measurements strongly indicate a stable carrier envelope slip and only small amount of random phase noise.
关键词： inter-sweep phase,optical coherence tomography,ring laser,FDML laser,phase stability
更新于2025-09-11 14:15:04
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Toward Phase Stability: Dion–Jacobson Layered Perovskite for Solar Cells
摘要： Three-dimensional halide based perovskites has emerged as promising semiconducting light harvester for thin-film solar cells fabrication, however, its intrinsic instability under humidity restricts their potential commercialization. To address such challenges, the development of low-dimensional Dion-Jacobson (DJ) phase / layered perovskites have recently gained substantial attention due to their intriguing environmental stability and competitive power conversion efficiency. In this review, we have screened and focused our investigation on the DJ phase in layered perovskite for solar cell fabrication, especially elucidation on the active role played by organic spacer cation for active layer. We also discuss the possible strategies that can be employed to further push the performance of DJ perovskite solar cells.
关键词： organic spacer cation,layered perovskites,Dion-Jacobson phase,phase stability,solar cells
更新于2025-09-11 14:15:04
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Color tunable carbon quantum dots from wasted paper by different solvents for anti-counterfeiting and fluorescent flexible film
摘要： Forecasting the structural stability of hybrid organic/inorganic compounds, where polyatomic molecules replace atoms, is a challenging task; the composition space is vast, and the reference structure for the organic molecules is ambiguously defined. In this work, we use a range of machine-learning algorithms, constructed from state-of-the-art density functional theory data, to conduct a systematic analysis on the likelihood of a given cation to be housed in the perovskite structure. In particular, we consider both ABC3 chalcogenide (I?V?VI3) and halide (I?II?VII3) perovskites. We find that the effective atomic radius and the number of lone pairs residing on the A-site cation are sufficient features to describe the perovskite phase stability. Thus, the presented machine-learning approach provides an efficient way to map the phase stability of the vast class of compounds, including situations where a cation mixture replaces a single A-site cation. This work demonstrates that advanced electronic structure theory combined with machine-learning analysis can provide an efficient strategy superior to the conventional trial-and-error approach in materials design.
关键词： hybrid organic/inorganic compounds,perovskite,density functional theory,machine-learning,phase stability
更新于2025-09-11 14:15:04