Evidence for Two Time Scale-Specific Blinking Mechanisms in Room-Temperature Single Nanoplatelets

Intermittent periods of low light emission (blinking) and time-dependent emission spectra (spectral diffusion, SD) have proven to be major obstacles to the adoption of colloidal semiconductor nanocrystals as quantum emitters. One clue to the mechanisms behind these two phenomena is how they are related, which is difficult to determine at time scales faster than can be captured using a spectrometer (similar to 100 ms). This work utilizes spectral correlations to access a range of time scales from 10 mu s to 10 s and determines that, for quasi-2D CdSe/CdS core/shell nanoplatelets (NPLs), blinking occurs on time scales from 100 pis to seconds but is only accompanied by SD on the similar to 1 s time scale and slower. This result indicates that shorter time scale blinking is due only to an equilibrium between dark and bright states with a shared, uncharged ground state, while longer time scale blinking receives contributions from an equilibrium between two distinct emissive states. The 10-15 meV energy range sampled by the NPL emission during SD implies that the two emissive states are an exciton and a trion.

Automated summary

This study investigates the emission characteristics of CdSe/CdS core/shell nanplatelets and finds that blinking primarily occurs on time scales from 100 ps to seconds, while spectral diffusion mainly occurs on time scales of approximately 1 second and slower. Shorter time scale blinking is attributed to an equilibrium between dark and bright states, while longer time scale blinking involves an equilibrium between two distinct emissive states.