Ambient Condition Mg<sup>2+</sup> Doping Producing Highly Luminescent Green- and Violet-Emitting Perovskite Nanocrystals with Reduced Toxicity and Enhanced Stability
Somnath Das, Apurba De, Anunay Samanta
Abstract
The lack of long-term stability, the presence of toxic lead, and a low photoluminescence (PL) efficiency are the major obstacles to the commercialization of lead-halide perovskite-based optoelectronic and photovoltaic devices. Herein we report a facile ambient condition doping protocol that addresses all three issues of the CsPbX 3 perovskite nanocrystals (NCs) to a substantial extent. We show that the room-temperature treatment of these NCs with MgX 2 results in the partial (18–23%) replacement of toxic lead, enhances the PL quantum yield of green-emitting CsPbBr 3 (to ∼100% from ∼51%) and violet-emitting CsPbCl 3 NCs (to ∼79% from ∼1%), and improves the stability under ambient conditions and in the presence of light and a polar solvent. Ultrafast pump–probe and temperature-dependent PL studies reveal that curing of the intrinsic structural disorder, introduction of some shallow energy levels close to the conduction band edge, and effective passivation of the halide deficiency contribute to the improved properties of the doped systems.