Activation Energy of Self-Trapped Excitons in Ruddlesden–Popper ACE2PbBr4 Perovskite under Hydrostatic Pressure

Abstract

Self-trapped excitons (STEs) are often observed in two-dimensional hybrid organic–inorganic perovskites, and they are characterized by a very large Stokes shift (200–800 meV) and an activation energy of ∼50–120 meV. Due to the high softness of organic–inorganic perovskites, their properties are often studied under high hydrostatic pressure, but the effect of pressure on the activation energy of STEs has not been studied so far. In this work, we investigated how the activation energy of STEs depends on the hydrostatic pressure for the Ruddlesden–Popper ACE2PbBr4 perovskite. By increasing the pressure to 2.6 GPa, the activation energy was observed to decrease from ∼100 to ∼25 meV. The observed changes can be explained quite well using a configuration diagram, which is widely used to explain STEs and free exciton emissions in organic–inorganic perovskites.