Electron transfer in photoexcited perovskite-chromophore hybrid assemblies: can it be static?

Here, we report the precise photo-selective PL quenching of colloidal perovskite nanocrystals (PNCs) by C60 employing steady-state and ultrafast time-resolved spectroscopic studies. The data reveal that the effective mechanism of the PL quenching of PNCs (FAPbBr3 nanocrystals) is due to ET from the VB (valence band) of PNCs to 1C60* instead of from the CB (conduction band) to C60. Multiple previous literature reports ignored the simultaneous excitation of C60 and PNCs, which led them to hypothesize the seemingly inappropriate phenomenon of "photoactivated static electron transfer" (PSET), where ET supposedly occurred from the CB of PNC to C60. This has been argued on the basis of the observation of the PL quenching of PNCs without the shortening of the exciton lifetime. Moreover, it appears that neglect of ground-state complex formation and its consequences may also lead to the erroneous PSET concept.