Improving Crystallization and Stability of Perovskite Solar Cells Using a Low-Temperature Treated A-Site Cation Solution in the Sequential Deposition

The two-step sequential deposition is a commonly used method by researchers for fabricating perovskite solar cells (PSCs) due to its reproducibility and tolerant preparation conditions. However, the less-than-favorable diffusive processes in the preparation process often result in subpar crystalline quality in the perovskite films. In this study, we employed a simple strategy to regulate the crystallization process by lowering the temperature of the organic-cation precursor solutions. By doing so, we minimized interdiffusion processes between the organic cations and pre-deposited lead iodide (PbI₂) film under poor crystallization conditions. This allowed for a homogenous perovskite film with improved crystalline orientation when transferred to appropriate environmental conditions for annealing. As a result, a boosted power conversion efficiency (PCE) was achieved in PSCs tested for 0.1 cm² and 1 cm², with the former exhibiting a PCE of 24.10% and the latter of 21.56%, compared to control PSCs, which showed a PCE of 22.65% and 20.69%, respectively. Additionally, the strategy increased device stability, with the cells holding 95.8% and 89.4% of the initial efficiency even after 7000 h of aging under nitrogen or 20-30% relative humidity and 25 °C. This study highlights a promising low-temperature-treated (LT-treated) strategy compatible with other PSCs fabrication techniques, adding a new possibility for temperature regulation during crystallization.

Enhanced Electrochemical Performance of Ni-Rich Cathodes by Neutralizing Residual Lithium with Acid Compounds

Surficial residual LiOH and/or Li₂CO₃ on Ni-rich cathodes arouse troubles for their practical applications, such as slurry gelling and durability degrading. To assure acceptable performance, the strategy of "washing and heat treatment" is generally utilized to remove them in industry, which is unavoidable to generate plenty of wastewater. In this work, we investigated the mechanism of slurry gelling caused by residual lithium on Ni-rich materials and then proposed a simple and efficient method to convert the detrimental residual lithium to the useful surface layer of LiF or LiBOB at 220 °C without water washing. As a result, the basicity of modified samples is lowered to 11.48 and 11.60 from 12.05 of the pristine, respectively. Owing to the beneficial effect of the surface layer, the treated samples deliver a discharge capacity of 189.5 and 187.9 mA h g^-1 and retain 84.1 and 82.8% of the initial capacity under 1 C after 300 cycles, which is much better than that of the untreated material (57.8%). The comprehensive performances of the modified samples in this work are very close to those of the material treated with the industrial method, demonstrating the advantage of this strategy to further reduce the cost of material production.

Head-down tilt position successfully prevent severe brain air embolism

Air embolisms are rare life-threatening complications that develop under various conditions, including surgery. During segmentectomy for thoracic surgery, air is blown into the selected bronchus for segment margin detection. This may result in the formation of an air embolus. Herein, we report a case of successful recovery from sudden intraoperative cardiac arrest due to an air embolism in a patient undergoing left superior division segmentectomy via open thoracotomy. Intraoperatively, the patient was positioned head-down. Upon blowing air into the bronchus, the patient suddenly developed cardiac arrest. Open-chest cardiac massage and low-temperature therapy were commenced and the patient recovered. The head-down position prevents the air embolus from reaching the brain and thus prevents severe brain damage, whereas continuous open-chest massage and low temperature prevents severe body damage from anticipated cardiac air embolism. Thus, operation in the head-down position is useful in preventing severe brain damage from brain air embolisms.