Tuning Photoluminescence of CsPbBr₃ Quantum Dots through Plasmonic Nanofingers

Abstract All‐inorganic perovskites have recently drawn considerable attention due to their excellent optoelectronic properties. With the help of gap‐plasmon nanostructures, the optical properties of perovskites can be tuned through the coupled near‐field. Here, the optical coupling between CsPbBr₃ quantum dots (QDs) and gap‐plasmon through placing QDs in a 2‐nm tetrahedral amorphous carbon gap region of collapsible Ag nanofingers is demonstrated. Compared to the CsPbBr₃ QDs on SiO₂, the photoluminescence (PL) of CsPbBr₃ QDs on collapsed nanofinger is enhanced by 4 times and the lifetime decreases from 11.04 to 3.8 ns. A Purcell‐enhanced emission can be achieved by combining QDs and plasmonic nanofingers. In addition, the intensity of PL can be manipulated by the polarization of incident light because of the different polarization responses of dimer nanofingers. More importantly, PL intensity shows a quadric dependence on the incident power and lasing‐like PL spectra can be observed at room temperature by continuous‐wave laser excitation. Such observations can be ascribed to the strong coupling between CsPbBr₃ QDs and surrounding Ag nanofingers. This finding indicates that it is possible to achieve lasing‐like PL through coupling CsPbBr₃ QDs to the near‐field of plasmonic nanostructures, which can enrich the applications of CsPbBr₃ QDs in nanolasing devices.