Locally collective hydrogen bonding isolates lead octahedra for white emission improvement

As one of next-generation semiconductors, hybrid halide perovskites with tailorable optoelectronic properties are promising for photovoltaics, lighting, and displaying. This tunability lies on variable crystal structures, wherein the spatial arrangement of halide octahedra is essential to determine the assembly behavior and materials properties. Herein, we report to manipulate their assembling behavior and crystal dimensionality by locally collective hydrogen bonding effects. Specifically, a unique urea-amide cation is employed to form corrugated 1D crystals by interacting with bromide atoms in lead octahedra via multiple hydrogen bonds. Further tuning the stoichiometry, cations are bonded with water molecules to create a larger spacer that isolates individual lead bromide octahedra. It leads to zero-dimension (0D) single crystals, which exhibit broadband ‘warm’ white emission with photoluminescence quantum efficiency 5 times higher than 1D counterpart. This work suggests a feasible strategy to modulate the connectivity of octahedra and consequent crystal dimensionality for the enhancement of their optoelectronic properties.

A Probe into the Path of the Moral Issues From the Perspective of Marxist Philosophy’s Practical Existence Theory

<em>In the present era of the rapid development of market-oriented economy, the strangeness between people, the division of production and the diversity of occupations, and the different thinking ways of individual lead everyone to stand in their own position. As a result, the western tragedy appears and the social moral problems are becoming more and more serious. Marx turns his philosophical attention to the way of human existence—practical activities and their historical development. This paper analyzes the current moral problems from the perspective of Marxist practical existentialism. The rational path of virtue is to regard people as a rational being and its acquirement mainly depends on the intellect to overcome the perceptual preference. The spiritual path of virtue regards human as a spiritual being and its acquisition is through dialectical deduction of spirit itself. The practical path of virtue is to emphasize human’s perceptual activity and understand and manage things through practical activities.</em>

Children as science journalists. A way to promote individual-lead learning and critical thinking, enhancing the participation of children in the dialogue between science and society

In the last two years SISSA Medialab designed, tested and evaluated two projects aiming at empowering children (in one case) and teenagers (in the other) to act as science journalists in order to promote a personal, critical attitude towards science and technology. The two groups produced a paper magazine and a blog, respectively, in a participatory process, in which adults acted as facilitators and experts on demand, but the youths were the leaders and owners of the products. Special care was taken to ensure inclusiveness, by involving in the project children and teenagers from any social class including those not especially interested in science and technology before participating in the project.