Impurity doping has been widely applied in nanomaterial synthesis for modulating the crystallographic phase, morphology, and size of nanocrystalline materials, but mostly by altering thermodynamic equilibriums of final products. Here...

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Two-dimensional (2D) perovskites are hybrid layered materials in which the inorganic lattice of an octahedron is sandwiched by organic layers. They behave as a quantum-well structure exhibiting large exciton binding energy and high emission efficiency, which is excellent for photonic applications. Hence, the cavity modulation and cavity devices of 2D perovskites are widely investigated. In this review, we summarize the rich photophysics, synthetic methods of different cavity structures, and the cavity-based applications of 2D perovskites. We highlight the strong exciton–photon coupling and photonic lasing obtained in different cavity structures. In addition, functional optoelectronic devices using cavity structures of 2D perovskites are also reviewed.

Low-dimensional metal halide perovskites are attracting extensive attentions due to their enhanced quantum confinement and stability compared to three-dimensional perovskites. However, low dimensional connectivity in the inorganic frameworks leads to strongly bounded excitons with limited absorption properties, which impedes their application in photovoltaic devices. Here, we show that by incorporating a strong electron accepting methylviologen (MV) cation, charge transfer (CT) at the organic/inorganic interface can effectively tune the optical properties in one-dimensional (1D) lead-halide perovskites. Both 1D MVPb2I6 and MVPb2Br6 display expanded absorption and photoresponse activity compared to CT inactive cations. The photoinduced CT process in MVPb2I6 was further characterized by transient absorption spectroscopy, which shows an ultrafast CT process within 1 ps, generating charge separated states. Our work unveils the interesting photophysics of these unconventional 1D perovskites with functional organic chromophores.