Printable and Writable CsPbBr₃/Cs₄PbBr₆Perovskite Quantum Dots as Fluorescent Inks for Down-Conversion Flexible ACEL Devices

Inorganic perovskites show excellent advantages over traditional quantum dots (QDs) and have great potential for application in light-emitting devices, display devices, and other fields. In this paper, CsPbBr₃/Cs₄PbBr₆QDs with different cesium-to-lead ratios are synthesized in one step at room temperature and in a simple environment without protective measures. Among them, the perovskite powder with a photoluminescence quantum yield (PLQY) of 54% and a series of ink additives are formulated into a perovskite fluorescent ink with high stability and printability. The inks are used not only for printing but also for writing with simple and convenient application conditions in mass production. Finally, the inks are used to combine ZnS:Cu flexible alternative current electroluminescent (ACEL) devices to produce two different structures of light conversion flexible ACEL devices in a full-printing manner. The material loss and cost of the devices are very low. Pattern drawing and printing can be performed selectively. Among them, the P-outside structure ACEL device has a high lumen efficiency of 77.43 lm/W, which shows the application potential of the ink in ACEL devices and promotes the process of perovskite materials from laboratory to industrial applications.