研究了一维双链钙钛矿材料C₅H₁₆N₂Pb₂I₆的光学各向异性。采用水相法合成了一维双链钙钛矿C₅H₁₆N₂Pb₂I₆晶体，采用光谱对其进行表征，其荧光发射的线性二色比可达17.4，高于已报道的一维单链C₄H₁₄N₂PbI₄钙钛矿。表明降低晶体的对称性可用于提高光学各向异性。进一步通过Kramers-Kronig关系获得钙钛矿的复介电常数及其双折射和二色性，其中二色性和双折射分别达到了1.5和1.3。

Organic–inorganic halide metal perovskites are an exciting class of two-dimensional (2D) materials that have sparked renewed interest for next-generation optoelectronics. In particular, the self-trapped excitons (STEs) in 2D perovskite with excellent optical properties suggest great potential in display and narrowband detection. A prerequisite of understanding STEs’ properties is correct identification of the underlying interaction that leads to STEs. Here, the optical properties of STEs in (iso-BA)2PbI4 are characterized through laser spectroscopy at various temperatures and excitation intensities. It is found that STEs are related to the octahedral distortion caused by strong electron–phonon interaction. Trapping and detrapping between STEs and free excitons (FEs) are clearly observed. With the increase in temperature, STEs and FEs will gain enough energy and migrate to each other. Moreover, by characterizing the thickness-dependent and two-photon excitation emission, it is confirmed that STEs exist inside the material because of their weak absorption. Our findings are of great significance for not only the fundamental understanding of STEs, but also the design and optimization of 2D-perovskite-based electronic and optoelectronic devices.

Two-dimensional (2D) perovskites exhibit broadband emission due to strong exciton–phonon coupling-induced self-trapped excitons and thus would find important applications in the field of white-light emitting devices. However, the available identifying methods for self-trapped excitons are currently rather limited and complex. Here, we identify the existence of self-trapped excitons by Raman spectroscopy in both excited and non-excited states. Under excited states, the shifting of the Raman peak indicates the presence of the lattice distortion, which together with the extra Raman scattering peak reveals the presence of self-trapped excitons. Our work provides an alternative simple method to study self-trapped excitons in 2D perovskites.

Two-dimensional (2D) hybrid organic-inorganic perovskites have recently attracted attention due to their layered nature, naturally formed quantum well structure, large exciton binding energy and especially better long-term environmental stability compared with their three-dimensional (3D) counterparts. In this report, we present a brief overview of the recent progress of the optoelectronic applications in 2D perovskites. The layer number dependent physical properties of 2D perovskites will first be introduced and then the different synthetic approaches to achieve 2D perovskites with different morphologies will be discussed. The optical, optoelectronic properties and self-trapped states in 2D perovskites will be described, which are indispensable for designing the new device structures with novel functionalities and improving the device performance. Subsequently, a brief summary of the advantages and the current research status of the 2D perovskite-based heterostructures will be illustrated. Finally, a perspective of 2D perovskite materials is given toward their material synthesis and novel device applications.