Hybrid perovskite photovoltaics combine high performance with the ease of solution processing. However, to date, a poor understanding of morphology formation in coated perovskite precursor thin films casts doubt on the feasibility of scaling-up laboratory-scale solution processes. Oblique slot jet drying is a widely used scalable method to induce fast crystallization in perovskite thin films, but deep knowledge and explicit guidance on how to control this dynamic method are missing. In response, we present a quantitative model of the drying dynamics under oblique slot jets. Using this model, we identify a simple criterion for successful scaling of perovskite solution printing and predict coating windows in terms of air velocity and web speed for reproducible fabrication of perovskite solar cells of ∼15% in power conversion efficiencyin direct correlation with the morphology of fabricated thin films. These findings are a corner stone toward scaling perovskite fabrication from simple principles instead of trial and error optimization.

No abstract

We report on the fabrication of condensed and mesoporous silica coated CoFe2O4 and FeCo alloy magnetic nanocomposites. The CoFe2O4 magnetic nanoparticles were encapsulated by well defined silica layer with a uniform thickness of 5 nm. The mesoporous silica shells lead to a larger magnetic coercivity than that of the pure CoFe2O4 magnetic nanoparticles due to decrease of interparticle interactions and magneto-elastic anisotropy. In addition, the FeCo nanoparticles were coated with condensed and mesoporous silica. As a consequence, the condensed silica protects the reactive FeCo alloy from oxidation up to 300 °C, maintaining the high magnetization of the nanoparticles. However, saturation magnetization of silica coated FeCo nanoparticles is dramatically decreased after annealing at 400 °C due to the oxidation of the FeCo core.

No abstract

No abstract