Ultrafast Dopant-Induced Exciton Auger-like Recombination in Mn-Doped Perovskite Nanocrystals

Manganese(II)-doped perovskite nanocrystals (NCs), because of their unique dual-color (from host excitons and Mn-dopants) emission property, are promising materials for various optical applications. Because the excited state at Mn2+ is extremely long-lived, one or more host excitons coexisting with an excited Mn2+ can be generated in the same NC under continuous excitation, and the behavior of exciton in the presence of excited Mn2+ can determine the optical property of Mn-doped NCs. Herein, by using pump–pump–probe transient absorption spectroscopy, we show that, in Mn-doped CsPbCl3 NCs, the host exciton can undergo ultrafast nonradiative Auger-like recombination (τAug ≈ 12 ps) when coexisting with the excited state at Mn2+. Such fast Auger-like process competes with the exciton-to-dopant energy transfer (τIET ≈ 303 ps) and, thus, allows the Mn-dopant emission from only one Mn2+ site per NC at a time. This dopant-induced Auger-like recombination should correspond to the broadly observed excitation-dependent saturation of dopant emission in Mn-doped NCs, and also makes the Mn-doped NC a potential single photon emitter.