Two-photon excited spin excitonic properties in two-dimensional chiral perovskite films

Two-dimensional (2D) chiral perovskites exhibit strong circular dichroism and two-photon absorption (TPA). A comprehensive understanding of the two-photon excited spin excitonic properties in 2D chiral perovskites is essential for the development of chirality related nonlinear optical (NLO) devices. In this work, we have constructed a series of 2D chiral perovskites with strong TPA coefficients using an achiral organic spacer cation alloying strategy. Importantly, the carrier dynamics of 2D chiral perovskites has been investigated, which exhibit different responses to left-handed and right-handed circularly polarized light. Interestingly, the microscopic images of two-photon excited circularly polarized luminescence (CPL) in chiral perovskites are demonstrated, confirming they possess large dissymmetry factors of CPL. This work not only sheds light on the two-photon excited spin excitonic mechanism in 2D chiral perovskites but also confirms the feasibility of their application in chirality related NLO devices.