Ultralow Threshold Room Temperature Polariton Condensation in Colloidal CdSe/CdS Core/Shell Nanoplatelets

Room-temperature exciton-polariton Bose-Einstein condensation (BEC), a phase transition to single quantum state with strong nonlinearity, provides a new strategy for coherent light sources and ultralow threshold optic switches. In this work, colloidal CdSe/CdS 2D nanoplatelets are embedded into a microcavity, and exciton-polariton BEC is realized with an ultralow threshold of 0.5 µJ cm^-2 at room temperature. The superlinear power-dependent emission, macroscopic occupation of the ground state, strong blueshift and broadening of the emission peak, and long-range coherence strongly confirm the realization of the polariton laser. This work suggests considerable prospects for colloidal nanoplatelets in low-cost, high-performance polariton devices, and coherent light sources.