Search

CsPbI3 perovskite is a promising light absorber in perovskite solar cells (PSCs) due to its suitable bandgap (Eg) and high chemical stability, but the perovskite phase is metastable in ambient atmosphere and prone to defect formation. To enhance phase stability and reduce defects, forming a low dimensional (LD) perovskite on CsPbI3 has proved effective. However, the energy levels for most of low‐conductivity LD perovskites are not very compatible with those of CsPbI3, which will impair charge separation and device performance. Herein, a new 1D perovskite (5‐Azaspiro[4.4]nonan‐5‐ium lead triiodide, ASNPbI3) with compatible energy levels and a large Eg is reported as a capping layer. The p‐type ASNPbI3 forms a p‐n heterojunction with n‐CsPbI3 with a staggered band alignment, considerably enhancing the carrier separation. Besides, by pre‐forming a ASNPbI3 at an intermediate stage, defects are suppressed in perovskite film. Consequently, the CsPbI3 PSCs based on carbon electrode without hole transporter (C‐PSCs) achieves a PCE of 18.34%, which is among the highest‐reported values for inorganic C‐PSCs. Furthermore, the hydrophobic ASNPbI3 capping layer has a high thermal stability that greatly enhances perovskite phase stability. Hence, the CsPbI3 C‐PSCs maintains 68% of its initial PCE after 400 h aging at 85°C in a N2 glovebox. [ABSTRACT FROM AUTHOR]

When selecting inhaled therapies, it is important to consider both the active molecules and the device. Extrafine formulation beclomethasone dipropionate plus formoterol fumarate (BDP/FF) has been available for some years delivered via pressurized metered-dose inhaler (pMDI). More recently, a breath-activated, multi-dose dry-powder inhaler (DPI), the NEXThaler, has been approved. The current study aimed to demonstrate the non-inferiority of BDP/FF delivered via the DPI vs. via the pMDI, in Chinese adults with asthma. After a four-week run-in period, when all patients received BDP/FF pMDI 100/6 µg, two inhalations twice daily (BID), patients were randomized equally to BDP/FF pMDI or DPI, both 100/6 µg, two inhalations BID for 12 weeks. The primary objective was to demonstrate non-inferiority of BDP/FF DPI vs. BDP/FF pMDI in terms of average pre-dose morning peak expiratory flow (PEF) over the entire treatment period. Of 252 and 242 patients in the DPI and pMDI groups, respectively, 88.5% and 88.8% completed the study. The primary objective was met, with no statistically significant difference between the treatments in average pre-dose morning PEF, and with the lower limit of the 95% CI above the −15 L/min non-inferiority margin (adjusted mean difference: 5.25 L/min [95% CI: −0.56, 11.06]). Adverse events were reported by 48.4% and 49.6% patients in the DPI and pMDI groups, respectively, most mild or moderate. The NEXThaler DPI is a similarly effective device to the pMDI for the administration of BDP/FF in adults, so extending the options available for the management of asthma. [ABSTRACT FROM AUTHOR]

The quest for high-performance solar cell absorbers has garnered significant attention in the field of photovoltaic research in recent years. To overcome the Shockley–Queisser (SQ) limit of ∼31% for single junction solar cell and realize higher power conversion efficiency, the concept of an intermediate band solar cell (IBSC) has been proposed. This involves the incorporation of an intermediate band (IB) to assist the three band-edge absorptions within the single absorber layer. BaSnS2 has an appropriate width of its forbidden gap in order to host an IB. In this work, doping of BaSnS2 was studied based on hybrid functional calculations. The results demonstrated that isolated and half-filled IBs were generated with suitable energy states in the band gap region after group-IIIA element (i.e., Al, Ga, and In) doping at Sn site. The theoretical efficiencies under one sun illumination of 39.0%, 44.3%, and 39.7% were obtained for 25% doping concentration of Al, Ga, and In, respectively; thus, larger than the single-junction SQ-limit. Furthermore, the dopants have lower formation energies when substituting the Sn site compare to occupying the Ba and S sites, and that helps realizing a proper IB with three band-edge absorptions. Therefore, group-IIIA element doped BaSnS2 is proposed as a high-efficiency absorber for IBSC. [ABSTRACT FROM AUTHOR]

Since non-methane hydrocarbons (NMHCs) include numerous species of volatile organic compounds (VOCs), they are the only indicators that can characterize the total amount of VOCs in ambient air. More than 90 % of NMHC instruments in the market use the indirect method for NMHC determination, utilizing a gas chromatograph to determine the concentrations of total hydrocarbons (THCs) and methane in air. However, we found indirect NMHC measurements incorrectly characterized the low NMHC concentrations in the urban air. These measurements were hindered by the uncertain changes in the errors associated with low THC concentrations, humidity and macroscopic substances (oxygen) in the atmosphere. In this study, we conducted intercomparisons between 10 instruments in the market using different operation principles; among these, two used the direct method, and eight used the indirect method. For the indirect method, experiments showed that when the NMHC concentration was 50 ppbC , the errors in the measurement results were 32 % (CH4) and 98 % (THC) when compared to theoretical values. The oxygen content in the sample gas directly affected the response of the THC. The effect of increased oxygen content on the analysis of oxygen-containing substances was more significant than that of the increase in hydrocarbon substances. The response of dry zero was blank, and the response value increased non-linearly with relative humidity (RH). RH had a great impact on low NMHC concentrations of nearly 50 %. For the direct method, although various flow designs were applied for different instruments, the results indicated that they generally showed lower interference and higher accuracy for the ambient NMHC measurements. With the online direct methods, we obtained more reliable data and characteristics for low-concentration NMHCs in downtown Shanghai. The median of hourly data was 163.1 ppbC , and the highest ratio of the maximum and minimum concentrations of NMHCs reached 9.56 in a single day. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbBr3 perovskite doped with alkali metal atoms has been attracting increasing attention due to its superior optoelectronic properties. However, there still exists significant uncertainty regarding the doping mechanism. One view of the mechanism is that alkali metal atoms tend to substitute Cs in CsPbBr3 crystals. Another view is that Li and Na tend to intercalate into interstitial sites because their radii are much smaller than that of Cs. To elucidate the doping mechanism, it is necessary to investigate the point defects physics of alkali metal elements in CsPbBr3. In this work, by using first-principles calculations we find that alkali metal atoms energetically prefer to substitute for Cs or Pb atoms in CsPbBr3 crystals under different chemical potential conditions. To determine the alkali metal atoms doping site, one should consider the chemical potential of synthesis conditions, the dopant valence states, and atomic radii. Notably, alkali metal atoms doping mainly introduces shallow levels, which is helpful for improving the p-type conductivity of CsPbBr3. [ABSTRACT FROM AUTHOR]

Propane catalytic oxidation is an important industrial chemical process. However, poor activity is frequently observed for stable C–H bonds, especially for non-noble catalysts in low temperature. Herein, we reported a controlled synthesis of catalyst Co3O4@CeO2–IE via inverse loading and proposed a strategy of oxygen vacancy for its high catalytic oxidation activity, achieving better performance than traditional supported catalyst Co3O4/CeO2–IM, i.e., the T50 (temperature at 50% propane conversion) of 217 °C vs. 235 °C and T90 (temperature at 90% propane conversion) of 268 °C vs. 348 °C at the propane space velocity of 60,000 mL g−1 h−1. Further investigations indicate that there are more enriched oxygen vacancies in Co3O4@CeO2–IE due to the unique preparation method. This work provides an element doping strategy to effectively boost the propane catalytic oxidation performance as well as a bright outlook for efficient environmental catalysts. [ABSTRACT FROM AUTHOR]