Comment on “Copper-Substituted Lead Perovskite Materials Constructed with Different Halides for Working (CH₃NH₃)₂CuX₄-Based Perovskite Solar Cells from Experimental and Theoretical View”

In recent years, two-dimensional perovskites have received considerable attention for their potential applications for optoelectronics. Contrary to previous publications, we demonstrate that (CH3NH3)2CuCl4 hybrid organic–inorganic layered perovskite does not show any room-temperature photoluminescence (PL) under UV excitation. This statement can be extended to other perovskites with general formula AMX3 or A2MX4, based on M: Cu2+ and X: Cl– or Br–. These materials, the object of increasing interest because of their efficient light absorption in a wide UV–vis–NIR range ideal for solar cells and optoelectronics, lack PL at room temperature, in contrast to recent findings reporting PL properties in this and other similar Cu2+-related materials.