Extended Data Fig. 3: Characterization for single-component white emissions.
From: Local lattice softening in semiconductor quantum dots for efficient white light-emitting diodes
a, PL mapping of Cl:ZnSe/ZnSe/ZnS QDs using filters of 420-480 nm and 495-550 nm, respectively. These filters enable the detection of emission occurring within their respective wavelength ranges. The individual QDs (circled in green) exhibit distinct bright dots under both filters, indicating that the white emissions originate from the same particle. b, PL intensity time trace of Cl:ZnSe/ZnSe/ZnS QDs for the two emissions detected by the aforementioned filters, respectively. The non-blinking behavior observed for each emission peak suggests the effective suppression of Auger combination process. The excited wavelength used is 405 nm. c, Photoluminescence excitation (PLE) spectra of Cl:ZnSe/ZnSe/ZnS QDs with different PL wavelengths covering the entire PL spectra. These PLE spectral profiles are almost identical, which rule out the possibility that the multiple emissions result from the radiation ensemble of different emitters. This observation is consistent with the fact that the optimal excitation wavelength varies for different materials. Any other scenario would result in a variation in the excitation spectrum with changes in the detection wavelength. d, PL spectra of Cl:ZnSe/ZnSe/ZnS QDs under varying excitation light. The insert provides a zoom-in view of the low-energy emission region under excitation wavelengths ranging from 470 to 650 nm. It is discernible that the broadband emissions vanish when the excitation wavelengths exceed 500 nm, illustrating that the low-energy emission is dependent on the energy or charge transfer from ZnSe host.
