Modifying the Crystal Field of CsPbCl₃:Mn²⁺ Nanocrystals by Co-doping to Enhance Its Red Emission by a Hundredfold

CsPbCl3:Mn2+ is a practical solution for obtaining red-orange light inorganic perovskite nanocrystals since CsPbI3 is unstable. Increasing the concentration of Mn2+ is an effective way to enhance the orange-red emission of CsPbCl3:Mn2+. However, the relationship between emission intensity of the Mn2+ dopant and the concentration of Mn2+ is very chaotic in different studies. As a transition metal ion, the electronic states of Mn2+ are very sensitive to the crystal field environment. Here, the crystal field of the CsPbCl3:Mn2+ nanocrystals was adjusted by co-doping other cations, and the concentration of Mn2+ remained unchanged. Additionally, the crystal field strength of different samples was calculated. Compared with the CsPbCl3:Mn2+ nanocrystals, the red-orange peak in the fluorescence spectrum of CsPbCl3:Mn2+, Er3+ nanocrystals was redshifted from 580 to 600 nm and enhanced by 100 times successfully. The same experiment was carried out on CsPbCl3:Mn2+ nanoplatelets at the same time to confirm the changed crystal field around Mn2+. The effect of co-doping cations on the luminescence properties of Mn2+ is similar to that in nanocubes, and the mechanism was analyzed in detail.