Effect of Washing Solvents on the Properties of Air-Synthesized Perovskite CsPbBr3 Quantum Dots for Quantum Dot-Based Light-Emitting Devices

In order to improve the stability and cost of perovskite CsPbBr
₃
and establish a preparation process for quantum dot materials with excellent luminescence properties, CsPbBr
₃
quantum dots were synthesized by the hot injection method and the ice bath method in air ambient. Then, a proprietary purification system was used to improve the properties of the quantum dots and prepare high-quality perovskite quantum dot films. Optimal material and light characteristics were exhibited with ethyl acetate:hexane as the purification solvent. In the solution form, the photoluminescence wavelength could be maintained at 508 nm with almost no shift compared with other conditions, and the quantum yield could reach 99%; however, superior performance was obtained in the thin-film form, which exhibited little to no shift in the photoluminescence wavelength and, surprisingly, achieved a quantum yield of 91.6% with a narrow PL emission with a full width at half-maximum of 28 nm. In addition, exceptional thin-film uniformity was observed from scanning electron microscopy image analyses. The CsPbBr
₃
quantum dot light-emitting diode purified with ethyl acetate:hexane demonstrated an open-circuit voltage of 4 V, a maximum luminous brightness of 488 cd m
^-2
, and a maximum external quantum efficiency of 0.14%.