Single Oxygen Molecule Sensitivity of Organolead Halide Perovskite Photoluminescence

The photoluminescence (PL) of organolead halide perovskites (OHPs) is sensitive to its surface conditions, especially surface defect states, making the PL of small OHP crystals an effective way to report their surface states. At the ensemble level, when averaging a lot of nanocrystals, the photoexcitation of OHP nanorods under inert nitrogen (N₂) atmosphere leads to PL decline, while subsequent exposure to oxygen (O₂) results to reversible PL recovery. At the single-particle level, individual OHP nanorods photoblinks, whose probability is dependent on both the excitation intensity and the O₂ concentration. Combining the two sets of information, we are able to quantitatively evaluating the interaction between a single surface defect and a single O₂ molecule using a kinetic model. This model provides fundamental insights that could help reconcile the contradicting views on the interactions of molecular O₂ with OHP materials and help design a suitable OHP interface for a variety of applications in photovoltaics and optoelectronics.