Abstract
Abstract Two-dimensional (2D) organic-inorganic hybrid perovskites have attracted growing attention recently due to their naturally formed quantum-well structure, unique photoelectric properties and better environmental stability compared to three-dimensional perovskites. The reduced screening and enhanced Coulomb interaction in 2D perovskites result in the formation of excitonic complexes. While the properties of free excitons have been well investigated, studies on biexcitons remain elusive. Here, we report on the biexcitons in 2D (iso-BA)2PbI4 (BA=C4H9NH3) crystals. The biexciton emission can be observed under a very low excitation power density of 6.4 W/cm2 at 78 K. The biexciton exhibits a large biexciton binding energy of 46 meV due to the large exciton binding energy of (iso-BA)2PbI4. Furthermore, the biexcitons exhibit a favorable polarization orientation, resulting in different anisotropy between biexcitons and excitons. Our findings would motivate more studies on biexcitons in 2D perovskites and pave the way for exploiting the many-body physics for biexciton lasing and optical storage devices.
Highlights
Two-dimensional (2D) organic-inorganic hybrid perovskites exhibit unique optical properties due to their naturally formed quantum well-structure and layered nature [1]
The significant difference in dielectric constant between the organic barrier layers and the inorganic well layers leads to the enhanced Coulomb interaction in the well layers, resulting in the extreme large exciton binding energy in 2D perovskites [2, 3]
The enhanced Coulomb interaction and the large nonlinear effect lead to the biexciton emission in2PbI4 perovskite under such low excitation power density
Summary
Two-dimensional (2D) organic-inorganic hybrid perovskites exhibit unique optical properties due to their naturally formed quantum well-structure and layered nature [1]. Due to the Coulomb interaction binding electrons and holes, quasi-particles named excitons are formed. The significant difference in dielectric constant between the organic barrier layers and the inorganic well layers leads to the enhanced Coulomb interaction in the well layers, resulting in the extreme large exciton binding energy in 2D perovskites [2, 3]. A series of novel optical properties, such as the formation of excitonic complexes, are present in 2D perovskites, which make 2D perovskites attractive for potential exciton-related applications [7, 8]
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