Unraveling Reversible Quenching Processes of O<sub>2</sub>, N<sub>2</sub>, Ar, and H<sub>2</sub>O in Metal Halide Perovskites at Moderate Photon Flux Densities
Edgar R. Nandayapa, Katrin Hirselandt, Christine Boeffel, Eva Unger, Emil List
Abstract
Abstract Metal halide perovskites (MHP), as used in photovoltaic (PV) applications, show a rich photophysics in inert and ambient atmosphere. The presence of atmospheric molecules leads to processes that enhance as well as reduce their photoluminescence (PL) emission. Various phenomena are previously described for a wide variety of gas molecules and different classes of MHP, with a particular interest on the long‐term stability for PV applications. However, reversible PL quenching (PLQ) processes, which may be regarded equally important for the performance of PV and other optoelectronic applications, are neglected in other studies. This holds true for O 2 and H 2 O, but especially for low‐reactive gases such as nitrogen and argon. Using low excitation densities, it is shown that noticeable—and reversible—PLQ, in addition to PL enhancements, can already be observed for O 2 , N 2 , and Ar as well as for H 2 O at low concentrations of 1 mbar. The nature and origin of the quenching processes are further elucidated by applying the Stern–Volmer analysis, also employed to determine whether static and dynamic PLQ processes happen for the different quenching gases. The strongest static PLQ is found for O 2 and H 2 O. MHPs in N 2 and Ar atmospheres display a moderate PLQ effect.