Are the emission quantum yields of cesium plumbobromide perovskite nanocrystals reliable metrics for their quality?

Room-Temperature Doping of CsPbBr3 Nanocrystals with Aluminum

B-site doping is an emerging strategy for tuning the emission wavelength of cesium lead halide ABX₃ nanocrystals. We present a simple method for the postsynthetic doping of CsPbBr₃ nanocrystals with aluminum at room temperature by exposing them to a solution of AlBr₃ in dibromomethane. Despite the much smaller ionic radius of Al³⁺ compared to that of Pb²⁺, nominal doping levels in a range from 8.1% to 24.3% were obtained when increasing the Al/Pb feed ratio from 1 to 4.5. Al³⁺ introduction leads to a hypsochromic shift of the photoluminescence (PL) emission of the CsPbBr₃ nanocrystals. The PL peak position is highly stable over at least 6 months and tunable in a range of 510 to 480 nm by increasing the doping level. Structural analyses revealed a linear correlation between the PL energy and the lattice parameter with a slope of -1.96 eV/Å.