Protein-Mediated Aqueous Synthesis of Stable Methylammonium Lead Bromide Perovskite Nanocrystals: Implications for Biological and Environmental Applications

Lead halide perovskites (HPs) hold great potential for the next generation of optoelectronic devices. However, their promise for real-world applications has not been realized because of their poor phase stability and decomposition when subjected to heat, moisture, and light. Here, we report a facile strategy for synthesizing highly stable, compositionally rich, and size-controlled methylammonium lead HP [CH3NH3PbX3 (X = Cl, Br, and I)] nanocrystals (HPNCs) in an aqueous environment, assisted by diverse proteins as capping agents. Freeing HPNC production of the complications of organic solvents provides much needed flexibility for the further cost-effective and efficient development of these structures. Stabilized by a delicate ionic balance during synthesis and via interactions with proteins, the synthesized protein-HPNCs exhibit high aqueous and colloidal stability over months. Protein capping also yields promising optical characteristics, including narrow emission wavelength and a photoluminescence quantum yield of up to ∼50%. Furthermore, we demonstrate that this approach can be extended to the synthesis of protein-mediated HPNCs with different chemistries and protein compositions. We anticipate that this method can serve as a general platform that can be used for the fabrication of a wide range of metal HPs for many biological and environmental applications including cell imaging and sensing.