Doping Mn²⁺ in Lead Halide Perovskite Nanocrystals: Successes and Challenges

Mn2+ ions doped in high-energy absorbing semiconductor host nanocrystals take away the exciton energy and result in spin-polarized d–d emission. For the last three decades this has been widely studied on group II–VI semiconductors. Recently, the doping has been extended to CsPbX3 perovskite nanocrystals. Although the optical transition follows a similar principle, in which the exciton energy is transferred to dopant Mn d-state, doping in perovskite also revealed several new fundamental aspects of doping and dopant-induced new optical properties. Here, anions which mostly tune the band gap controlled the fate of the appearance of Mn emission. Also, the doping process was observed to be different than traditional growth doping. Hence, in perovskite host nanocrystals, while some aspects of Mn doping are found to be in agreement with previous findings, some new facts also surfaced. Combining all these facts, this Perspective focuses on the journey of Mn doping from group II–VI semiconductors to lead halide pe...