A chameleon under pressure: The observed piezochromic behavior of the title compound (BP2VA) was found to depend on its molecular aggregation state and specifically on the strength of the π–π interaction between the anthracene rings of adjacent molecules. When BP2VA is ground or placed under pressure, its molecular aggregation state changes, and a red shift in the fluorescence emission from green via orange to red occurs (see picture).

The high photoluminescence efficiency, high color purity, and easy tunable bandgap make inorganic perovskite nanocrystals very attractive in luminescent display applications. Here, we report a color-saturated, red light-emitting diode (LED) using an inverted organic/inorganic hybrid structure and perovskite nanocrystals. We demonstrated that through a simple post treatment to the perovskite nanocrystals with polyethylenimine, the surface defects of the perovskite nanocrystals could be well passivated, leading to great enhancements on their absolute photoluminescence quantum yield and photoluminescence lifetime. Through using a well-passivated perovskite nanocrystal film and optimizing the charge balance, we achieved an electroluminescence LED with a current efficiency of 3.4 cd A, corresponding to an external quantum efficiency (EQE) of 6.3%, which is the highest value reported among perovskite NC LEDs so far.

No abstract

No abstract