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Formamidinium lead triiodide (FAPbI3) perovskite without methylammonium and/or Cs cations is considered the most promising candidate for perovskite photovoltaics. However, the crystallization of photoactive α‐FAPbI3 requires high‐temperature annealing (≥150 °C) and a controlled humidity environment when methylammonium‐containing additives are absent. A methylammonium‐free ink is reported that enables low‐temperature (≤80 °C) crystallization of photoactive α‐FAPbI3 films, while also demonstrating compatibility with blade‐coating large‐area films in ambient air. The synergistical effects of methylphenyl sulfoxide and PbCl2 facilitate the formation of an intermediate phase of nanoscale‐disordered δ‐FAPbI3, which dramatically reduces the crystallization temperature of α‐FAPbI3 down to 80 °C and even below. The 80 °C crystalized α‐FAPbI3 exhibits reduced strain and improved uniformity compared to high‐temperature annealed counterparts. The synthesized ink and the corresponding intermediate precursor film are also found remarkably stable, allowing open‐air processing without the need for humidity control. Highly efficient n–i–p structured α‐FAPbI3 minimodules can be fabricated under an ambient environment RH 50% with the ink at 80 °C, achieving a power conversion efficiency of up to 22.4%. The discovery of the low‐temperature FAPbI3 ink paves a new avenue for printing perovskite solar cells and associated optoelectronic applications, accelerating the commercialization progress of perovskite materials. [ABSTRACT FROM AUTHOR]

The preparation of pristine formamidinium lead tri‐iodide (FAPbI3) perovskite films for solar cells applications can be very challenging without methylammonium containing additives. The pinhole‐rich films prepared by methylammonium‐free approach limit the performance of the pristine FAPbI3 perovskite solar cells (PSCs). This work proposes a recrystallization method employing mixed solvent annealing (MSA) to heal the pinholes in pristine FAPbI3 perovskite films. The tetramethylene sulfoxide vapor is demonstrated most effective in grains‐merging and pinhole healing, while the addition of a secondary solvent vapor of anisole significantly improved the uniformity of TMSO vapor distribution. The pristine FAPbI3 PSCs prepared with MSA recrystallized film achieved power conversion efficiencies up to 22.43% and 16.54% on small cells (0.105 cm2) and mini‐modules (12.6 cm2), respectively, showing great potential in upscaling fabrication of perovskite photovoltaics with pristine FAPbI3. [ABSTRACT FROM AUTHOR]

An instant p-doping strategy employing 4-tert-butyl-2-chloropyridine and tert-butyl peroxybenzoate for the spiro-OMeTAD hole-transport layer (HTL) in perovskite solar cells (PSCs) is proposed to replace the conventional 4-tert-butylpyridine-doped HTL. The novel doping process eliminates the formation of pores in the HTL. Meanwhile, a 21.4% efficiency is achieved on the corresponding absolute methylammonium-free PSCs with significantly improved thermal and moisture stability. [ABSTRACT FROM AUTHOR]

Grain boundaries of metal halide perovskites contain massive defects that are detrimental to photovoltaics applications. This work demonstrates that inorganic NH4NO3 can selectively passivate the grain boundaries of perovskite films and improve their moisture resistance simultaneously, resulting in enhanced performance and stability of the methylammonium-free perovskite solar cells. [ABSTRACT FROM AUTHOR]

Previous studies revealed that changing the electrode structures of a gallium arsenide photoconductive semiconductor switch (GaAs PCSS) can significantly affect the local electric field and current density at the electrodes. Knowing the optimization of the electrode structures of GaAs PCSS can improve the withstand voltage performance and current carrying capability. In this work, we optimize the surface contact electrode structure of GaAs PCSS, and numerical simulations are performed to systematically study the electric field and current density distribution in the bulk of the device. The result shows that the maximum transverse current density and maximum longitudinal current density of the embedded 172° isosceles trapezoid electrode structure are smaller than other kinds of electrode structures, which is the most favorable for improving the withstand voltage and current carrying capability of GaAs PCSS. [ABSTRACT FROM AUTHOR]

To investigate the influence of calcium chloride (CaCl2) in coal seams on the rheological property of a foam fracturing fluid, the guar powder was used as a foam stabilizer, and the anionic and cationic surfactants were used as foaming agents. The impact of CaCl2 concentrations on the foaming volume, half-life, viscosity, and surface tension of foam was investigated. The results show that CaCl2 has a more significant effect on the foaming amount and foam stability of the anionic surfactant-prepared foam. When the concentration of CaCl2 exceeds 0.25%, the viscosity of the base fluid shows a downward trend and gradually tends to a stable level below 10 mPa s. The foam half-life increases as the shape parameter an in the gamma function increases and decreases as the scale parameter b increases. The effect of CaCl2 on the bubble size of the anionic surfactant foam fracturing fluid is significantly greater than that of the cationic surfactant foam fracturing fluid. For coal reservoir foam fracturing, a foaming agent with better CaCl2 compatibility should be employed to reduce the influence of CaCl2 in the formation water on fracturing performance. [ABSTRACT FROM AUTHOR]

This article, titled "Methylammonium-Free Ink for Low-Temperature Crystallization of α-FAPbI3 Perovskite," was published in the journal Advanced Energy Materials. The authors, Tian Hou, Meng Zhang, Xiaoran Sun, Yihao Wang, Kaipeng Chen, Zhipeng Fu, Mingrui He, Xu Liu, Ziheng Liu, Yuelong Huang, Martin A. Green, and Xiaojing Hao, discuss a new method for fabricating α-FAPbI3 perovskite at low temperatures without the use of methylammonium (MA). The article includes an image illustrating the phase transition from hexagonal δ-FAPbI3 to cubic α-FAPbI3, and explains how the addition of PbCl2 and MPSO helps facilitate this transition. For more details, readers are directed to the full article. [Extracted from the article]

Controlling nickel particle size and inhibiting coke deposition on the supported catalyst are enormous challenges. To solve these problems, La-doped nickel-based catalysts using MCM-41 as the support were prepared via the radio frequency (RF) plasma-enhanced method. The Ni–La–Imp–P catalyst with a smaller nickel particle size, higher nickel dispersion, and a stronger metal–support interaction possessed more surface adsorbed oxygen than the conventional Ni–La–Imp catalyst, which was beneficial for the formation of more active Ni sites and enhanced the catalytic performance. In particular, the Ni–La–Imp–P catalyst showed excellent resistance to carbon deposition, and the carbon weight loss of the spent catalyst was only 5.94%, which was much less than those of conventional Ni–La–Imp (18.49%) and Ni–La–Sol (12.60%) catalysts. Nickel nanoparticles can effectively inhibit the growth of the carbon chain or the formation of the C–C bond to cover the surface site of Ni–La–Imp–P, thus reducing the formation of graphitic carbon and realizing the directional conversion of C (CH4 and CO2). Hence, the Ni–La–Imp–P catalyst activated by plasma proved to be a new method for enabling resistance to carbon deposition in dry reforming of methane. [ABSTRACT FROM AUTHOR]

Abstract The propagation characteristics of curved detonation have been extensively investigated in the present study using three types of stoichiometric test mixtures (2H 2 +O 2 +3Ar, C 2 H 4 +3O 2 , and CH 4 +2O 2) in a new experimental facility consisting of a straight channel joined to a helical channel. The helical channel with different inner radii (R i = 60 mm, 70 mm, and 80 mm) and uniform outer radius (R o = 100 mm) were used. Flame propagation through the helical channel was observed by high-speed CCD camera, and the trajectories of triple points on the detonation waves were obtained using a soot-deposition plate. The results clearly identify three detonation propagation modes, namely, a stable mode, critical mode, and unstable mode. A definite flame shape, which is perpendicular to the inner wall of the channel, is observed for the stable mode. The smooth flame front becomes more wrinkled as p 0 and/or R i decreases. Three types of patterns of cellular structure are observed for unstable mode, which present specific features of the periodical variation with various mixtures and curvatures, such as periodical disappearance near the inner wall, "petals"-like structure, and intermittent structure. Moreover, the ratio R i / λ is introduced as a sensitivity parameter to characterize the ability of a detonation. The detonation limits are found to be at the range of 2.6 ≤ R i / λ ≤ 4.8 in the present study. [ABSTRACT FROM AUTHOR]