Single silica-coated Mn-doped CsPbCl3 perovskite quantum dots with enhanced stability and excellent optical properties

Halide perovskite quantum dots (QDs) have been considered to be a potential emitting materials for illumination and display applications. Unfortunately, the toxicity and poor stability can greatly limit their practical application. Herein, the Mn2+-doped CsPbCl3 and SiO2-coated Cs(Pb,Mn)Cl3 perovskite QDs have been developed to solve the tricky problem without affecting their optical properties. Firstly, the mono-dispersed pure CsPbCl3 perovskite QDs with cubic morphologies are prepared by using a modified hot-injection method, as a control group. Next, the low-Pb content Cs(Pb,Mn)Cl3 perovskite QDs with distinctive dual emission peaks has been successfully obtained, including the CsPbCl3 host emission and the Mn2+ emission. Based on this, a new strategy for synthesizing single Cs(Pb,Mn)Cl3@SiO2 core-shell QDs with their initial cubic morphology and optical properties has been developed, which using the Cs(Pb,Mn)Cl3 nanoparticles as a precursor and choosing the APTES as the surface ligand. Photo-stability tests indicate that the Cs(Pb,Mn)Cl3 and Cs(Pb,Mn)Cl3@SiO2 perovskite QDs are markedly more stable than the pure CsPbCl3 QDs, indicating that the crystal engineering and host packaging are all effective way to improve the stability. Meanwhile, the PL intensity of Cs(Pb,Mn)Cl3@SiO2 dispersed in a mixed solution of toluene and water can retained 63% of the initial value even after 14 h, which are much higher than Cs(Pb,Mn)Cl3 (31%). Therefore, the Cs(Pb,Mn)Cl3 after SiO2 coating is the more effective way to improve stability than that of the Mn2+ doping. This work not only provides a simple and reliable synthesis way to synthesize the single core-shell particles, which can be suitable for other perovskite systems, but also compares the two methods of the crystal engineering and the host packaging to improve the stability of perovskite QDs for practical application.