Monitoring the Doping and Diffusion Characteristics of Mn Dopants in Cesium Lead Halide Perovskites

Cesium lead perovskites, in the form of CsPbX 3 or Cs 4 PbX 6, have been widely used for various optoelectronic applications due to their exceptionally good optical properties. In this study, the effect of Mn doping on the structural and optical properties of cesium lead halide perovskite crystals are investigated from both experimental and theoretical points of view. It is found that adding MnCl 2 during the synthesis not only leads to a Mn-driven structural phase transition from Cs 4 PbBr 6 to CsPbCl 3 but also triggers the Br – to Cl – halide exchange. On the other hand, it is observed that, under UV illumination, the color of Mn-doped crystals changes from orange to blue in approximately 195 h. While the intensity of Mn-originated photoluminescence emission exponentially decays in time, the intensity of CsPbCl 3 -originated emission remains unchanged. In addition, diffusive motion of Mn ions results in both a growing population of MnO 2 at the surface and transition of the host into a cesium-rich Cs 4 PbCl 6 phase.