Biexciton-like Auger Blinking in Strongly Confined CsPbBr3 Perovskite Quantum Dots

Perovskite quantum dots (QDs) with high room-temperatureluminescenceefficiency have been applied in single-photon sources. While the opticalproperties of large, weakly confined perovskite nanocrystals havebeen extensively explored at the single-particle level, few studieshave focused on single-perovskite QDs with strong quantum confinement.This is mainly due to their poor surface chemical stability. Herewe demonstrate that strongly confined CsPbBr3 perovskiteQDs (SCPQDs) embedded in a phenethylammonium bromide matrix exhibita well-passivated surface and improved photostability under intensephotoexcitation. We find that in our SCPQDs, photoluminescence blinkingis suppressed at moderate excitation intensities, and increasing theexcitation rates leads to weak photoluminescence intensity fluctuationsaccompanied by an unusual spectral blue-shift. We attribute this toa biexciton-like Auger interaction between excitons and trapped excitonsformed by surface lattice elastic distortions. This hypothesis iscorroborated by the unique repulsive biexciton interaction observedin the SCPQDs.