This studies describes the use of thick shell QDs as a core to be passivated by thin silica shell on the surface in order to maintain the brightness and enhance stability for display or lightening application. The coating with silica shell on the QDs surface is widely used to enhance stability against oxidation by blocking the exposure to oxygen or water. Even though silica coating on the QD surface has been improved in recent years, the literature is lacking a demonstration of QD@SiO2 with high brightness. By using thick-shell quan-tum dots, the PL QY was maintained as 72 %, which is the best record to our knowledge. Furthermore, the practical issue for a film formation application was also focused. The thickness was fine-tuned to adjust the concentration for each application, and we obtained silica-coated QDs ranging from 6 nm to 26 nm without any change in emission peak. In addition, the morphology of the resultant particle was adjusted by lowering the entire concentration of the reaction batch, optimizing the number of quantum dots embedded in one sili-ca sphere close to unity. Using this method, the optical interference can be avoided by keeping distance be-tween particles. For the film formation, treatment of silica particles with organoalkoxy silane was performed by enhancing the affinity to polymer. The ODTMS-treated QD@SiO2 NPs were successfully incorporated into a polymer matrix for the film formation, which presented the possibility of display or brightening applica-tions.