Deep-Blue CsPbBr₃ Perovskite Quantum Dots via Green Polar Solvent and Short Ligand Engineering towards Highly Efficient Light-Emitting Diodes

To date, researchers face a huge challenge in synthesizing blue perovskite quantum dots (PQDs) with short-chain ligands since the short-chain ligands increase the polarity and decrease solubility in common non-polar solvents during syntheses. The use of polar solvents to replace non-polar ones may solve the solution problem, but polar solvents will decompose PQDs. So, the key to successful synthesis of PQDs with short-chain ligands is to find polar solvents that can dissolve short-chain ligands well and do not destroy perovskites concurrently. Herein, a room-temperature synthesis method for deep-blue CsPbBr3 PQDs with short-chain ligands is proposed by using eco-friendly ethyl acetate polar solvent. CsPbBr3 PQDs with an average size of 3.87 nm and a peak wavelength of 454 nm are synthesized with a photoluminescence quantum yield of 48.4%. With an interlayer modification to the hole transport layer, the deep-blue perovskite light-emitting diodes realize a maximum external quantum efficiency of 4.39% and half-lifetime of 4.5 min at a maximum brightness of 72 cd m(-2). This work offers a novel eco-friendly avenue for the preparation of effective PQDs including blue ones, which will accelerate commercialization of PQDs in lighting and HD full-color displays as well as reduce discharge of solvent pollutants and protect the global environment.