Pb ²⁺ /Mn ²⁺ co-doping enables blue-to-white luminescence tuning in Rb₃Cd₂Cl₇ metal halide perovskites

All-inorganic metal halide perovskite materials exhibit high photoluminescence quantum yields (PLQYs), broad emission bands, and tunable luminescence-attributes that confer great potential for white light applications. However, reports on Cd-based perovskites for efficient white light emission remain scarce. Here, the hydrothermal synthesis of Pb²⁺/Mn²⁺co-doped Rb₃Cd₂Cl₇ perovskite crystals, in which the substitutions of Cd²⁺by Pb²⁺or Mn²⁺form the luminescent centers of [PbCl₆]⁴^-and [MnCl₆]⁴^-for white emission, is reported. Doping with Pb²⁺enables a deep-blue emission at 443 nm with anti-thermal quenching and a maximum PLQY of 58.58%, attributed to the formation of confined exciton around [PbCl₆]⁴^-. Concurrently, Mn²⁺ion doping induces energy transfer toward intrinsic self-trapped exciton (STE) states to [MnCl₆]⁴^-, yielding intense yellow emission at 588 nm with a maximum PLQY of 137.79%. This emission is attributed to the intrinsic Cd-related STEs, combined with the generation of local exciton magnetic polarons (LEMPs) through ferromagnetic (FM) Mn²⁺-Mn²⁺interactions, via assistance of the coupling with the 245.3 cm^-1phonon mode in Rb₃Cd₂Cl₇: Mn²⁺. The co-emission of^PbCE and LEMP, from the interaction of Pb²⁺and Mn²⁺centers, achieved a PLQY of 75.4% for white light emission. The white light-emitting diodes exhibit an excellent color rendering index of 94.1, which is exceptional among recent devices compared to those based on Cd. This underscores its potential for significant applications in the optoelectronic field and offers a new alternative material for perovskite blue and white LEDs.