Meeting High Stability and Efficiency in Hybrid Light‐Emitting Diodes Based on SiO2/ZrO2 Coated CsPbBr3 Perovskite Nanocrystals

Significant advances are realized in perovskite‐converted hybrid light‐emitting diodes (pc‐HLEDs). However, long‐living devices at high efficiencies still represent a major milestone with average stabilities of <200 h at ≈50 lm W−1 under low applied currents (<15 mA). Herein, a dual metal oxide‐coated CsPbBr3@SiO2/ZrO2 composite is prepared in a one‐pot synthesis through the kinetic control of the sol–gel reaction, followed by a gentle drying process in air. These hybrid nanoparticles show photoluminescence quantum yields of ≈65% that are stable under temperature, ambient, and irradiation stress scenarios. This is translated to pc‐HLEDs with a near‐unity conversion efficiency at any applied current, high efficiencies around 75 lm W−1, and one of the most remarkable stabilities of ≈200 and 700 h at 100 and 10 mA, respectively. In addition, the device degradation mechanism is thoughtfully rationalized comparing devices operating under ambient/inert conditions. As such, this work provides three milestones: i) a new room temperature one‐pot protocol to realize the first SiO2/ZrO2 metal oxide coating that effectively protects the emitting perovskite nanoparticle core, ii) one of the most stable and efficient pc‐HLEDs operating under ambient condition at any applied current, and iii) new insights for the degradation of pc‐HLEDs.R.D.C. acknowledges the program “Ayudas para la atracción de talento investigador—Modalidad 1 of the Consejería de Educación, Juventud y Deporte—Comunidad de Madrid with the Reference No. 2016‐T1/IND‐ 1463,” Spanish Ministry of Economy and Competitiveness (MINECO) for the Ramón y Cajal program (RYC‐2016‐20891), and HYNANOSC (RTI2018‐099504‐A‐C22). Y.Y.D. also thanks the financial support from China Scholarship Council (No. 201808440326). This work was supported by the Spanish MICINN and Agencia Estatal de Investigación (AEI)/European Regional Development Fund (FEDER) (Projects CTQ2015‐74494‐JIN, CTQ2016‐78463‐P, RTI2018‐099504‐B‐C21/A‐C22, and PID2019‐109742GB‐I00). E.S. thanks Universidad de Alicante through the “Programa de Retención de Talento” (ref. UATALENTO16‐03) and C.E. thanks Universidad de La Rioja for a grant. Open access funding enabled and organized by Projekt DEAL

Dual-Phosphorescent Heteroleptic Silver(I) Complex in Long-Lasting Red Light-Emitting Electrochemical Cells

The design of red-emitting silver(I) complexes and their implementation in thin-film lighting are still challenging as (i) their high ligand-field splitting energy leads to high-energy emissions with a controversial mechanism (thermally activated delayed fluorescence vs fluorescence/phosphorescence), and (ii) their low electrochemical stability leads to the formation of silver nanoclusters, limiting device stability to a few seconds. Herein, a thoughtful complex design [Ag(xantphos)(deebq)]PF6 combining a large-bite angle diphosphine ligand (xantphos), a rigid, sterically hindered, π-extended biquinolin (deebq) is reported. In contrast to prior-art, this complex possesses (i) efficient red-emission (λem = 660 nm; photoluminescence quantum yield of 42%) assigned to a thermally equilibrated dual-phosphorescent emission based on spectroscopic/theoretical studies and (ii) stable reduction behavior without forming silver nanoclusters. This results in the first red light-emitting electrochemical cells featuring (i) improved stability of two orders of magnitude compared to prior-art (from seconds to hours) at irradiances of 20 µW cm−2, and (ii) a new degradation mechanism exclusively related to p-doping as confirmed by electrochemical impedance spectroscopy analysis. Indeed, a multi-layered architecture to decouple hole injection/transport and exciton formation enables a further 2-fold enhanced irradiance/stability. Overall, this work illustrates that deciphering the rules for silver(I) complex design for lighting is tricky, but worthwhile.S.L. and L.M.C. contributed equally. R.D.C. acknowledges the European Union's Horizon 2020 research and innovation MSCA-ITN STiBNite No. 956923.Open access funding enabled and organized by Projekt DEAL.Peer reviewe

Can environment or allergy explain international variation in prevalence of wheeze in childhood?

Asthma prevalence in children varies substantially around the world, but the contribution of known risk factors to this international variation is uncertain. The International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two studied 8–12 year old children in 30 centres worldwide with parent-completed symptom and risk factor questionnaires and aeroallergen skin prick testing. We used multilevel logistic regression modelling to investigate the effect of adjustment for individual and ecological risk factors on the between-centre variation in prevalence of recent wheeze. Adjustment for single individual-level risk factors changed the centre-level variation from a reduction of up to 8.4% (and 8.5% for atopy) to an increase of up to 6.8%. Modelling the 11 most influential environmental factors among all children simultaneously, the centre-level variation changed little overall (2.4% increase). Modelling only factors that decreased the variance, the 6 most influential factors (synthetic and feather quilt, mother’s smoking, heating stoves, dampness and foam pillows) in combination resulted in a 21% reduction in variance. Ecological (centre-level) risk factors generally explained higher proportions of the variation than did individual risk factors. Single environmental factors and aeroallergen sensitisation measured at the individual (child) level did not explain much of the between-centre variation in wheeze prevalence

rotundifolia

Campanula rotundifolia Linnaeuscampanule à feuilles rondes;campanule à feuille rondeCampanula rotundifoliaCardston Gatedry N. W. facing grassy hillside4200 fee

Vita Haroldi. The romance of the life of Harold, king of England. From the unique manuscript in the British museum.

Mode of access: Internet

The Real Situation of Modern Monetary Theory in Japan

Modern Monetary Theory（MMT）attracts attention and debate all over the world. MMT argues that governments that can issue currency will never go bankrupt. The primary constraint on government spending is not the fiscal deficit but inflation. The Japanese government has historically pursued deficit spending to stimulate the economy and fund various projects. MMT has its roots in the works of economists like Abba Lerner and Hyman Minsky and debate among economists and policymakers still continues. The focus should be on the fact that banks can create money through lending and the government can influence money supply through taxation and spending policies. While critics claim that excessive government spending has led to fiscal collapse. Japan actually has one of the highest levels of government debt relative to GDP among developed countries. This debt is largely financed through the issuance of Japanese Government Bonds（JGBs）which are subject to monetary easing through exchanges between the government, the Bank of Japan, and commercial banks. The situation is dynamic and subject to evolving economic conditions and policy choices. We will analyze this situation in Japan and discuss the legitimacy of MMT.departmental bulletin pape