Enhancing the efficiency of CsPbX3 (X = Cl, Br, I) nanocrystals via simultaneous surface peeling and surface passivation.

Inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (PNCs) are promising materials for next-generation optoelectronic applications due to their tunable emission and high color purity. However, there is still room to improve their photoluminescence quantum yields (PLQYs) in order to promote their applications. Herein, the PLQY of blue light emitting CsPb(Cl/Br)3 PNCs was increased to 83% with ammonium hexafluorophosphate by choosing an appropriate treatment time. The salt peeled off the outermost surface of PNCs with halide vacancies and then passivated the surface. This method is effective at improving the PLQYs of different CsPbX3 (X = Cl, Br, I) PNCs covering the entire visible spectrum; the PLQYs were improved to 25% for CsPbCl3 at 398 nm, 83% for CsPb(Cl/Br)3 at 448 nm, 96% for CsPbBr3 at 504 nm, 86% for CsPb(Br/I)3 at 568 nm, and 98% for CsPbI3 at 687 nm.