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Despite recent surge of interest in semiconducting perovskite nanocrystals as the new type of quantum dots exhibiting superior optical properties compared to many existing quantum dot systems, precise control of quantum confinement and dimensionality has been challenging. We developed a strategy that controls the quantum confinement in colloidal CsPbX3 quantum dots very precisely resulting in the exciton emission nearly free from the heterogeneous broadening in an ensemble of quantum dots at room temperature. Built upon the exquisite control of quantum confinement achieved in this system, we uncovered an unusual exciton property in strongly confined CsPbX3 quantum dots. For instance, the confinement of exciton in the same space as the photo-generated polaron activated the parity-forbidden exciton transition via symmetry breaking, which illustrates the unique nonlinear optical behavior that results from the strong electron-phonon coupling in perovskite quantum dots. We also developed a procedure to introduce the magnetic dopants, such as Mn2+, into the lattice of CsPbI3 quantum dots, where one can potentially create exciton magnetic polaron, i.e., creating optically induced ferromagnetic state. From the comparison of the temperature-dependent shift of the exciton transition energy and lifetime of the emission in both doped and undoped CsPbI3 quantum dots, we investigated the conditions under which the exciton magnetic polaron can be created in magnetically doped perovskite quantum dots. The results from this study demonstrate the potential of the perovskite quantum dots with precisely controlled quantum confinement and magnetic doping as the single photon emitter or carrier of the quantum information applicable for future quantum information processing applications.
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