Unveiling Dopant‐Induced Ultrafast Exciton Dynamics in Mn/Yb Codoped Perovskite Nanocrystals

Abstract Perovskite nanocrystals (NCs) with intentionally introduced Mn 2+ /Yb 3+ activators enable tunable emissions covering UV‐orange‐NIR spectral range. However, the exact microscopic energy transfer mechanisms in this system remain unknown. Herein, Mn/Yb codoped CsPbCl 3 perovskite NCs with triple emissions originated from exciton recombination of host, 3d–3d transition of Mn 2+ and 4f–4f transition of Yb 3+ are prepared. Femtosecond resolution transient absorption spectra performed on the pristine CsPbCl 3 , Mn‐doped, Yb‐doped and Mn/Yb codoped samples clarify efficient and simultaneous energy transfer (ET) from excitons to Mn 2+ and Yb 3+ dopants. It is testified the sensitizations of dopants mainly result from the trapped hole, taking 285 ps for Mn 2+ and 17 ps for Yb 3+ respectively, which make less trapped hole recombine with de‐localized carriers. Importantly, energy transfer processes from host to Mn 2+ and Yb 3+ activators emerge as competition, and the ET probability of exciton‐to‐Mn 2+ is higher than that of exciton‐to‐Yb 3+ . Finally, control experiments further prove that tunable Mn 2+ orange emission and Yb 3+ NIR emission are achievable via elaborate adjustment of the dopant concentrations.