Precise Control Light Emission of PVDF-CH 3 NH 3 PbBr 3- x Cl x Nanocrystalline Films Using a Cl - (CH 3 OH) n System.

Methylammonium lead halide perovskites with highly efficient pure-color or white-light generation have gained increasing scientific interest and promote the development of a great commercial opportunity in displays, lighting, and other applications. However, the poor stabilities, lead toxicity, and unfriendly solvents and ligands in the growth process severely restrict their commercial application. Here, we proposed a green method for preparing uniform and stable polymer-encapsulated photoluminescence (PL) tunable CH 3 NH 3 PbBr 3- x Cl x NC thin films at room temperature. Utilizing the swelling effect between alcohol compounds and organic polymers and the ionization of NaCl in methanol solution, the anion exchange process can be achieved rapidly within 7 min. Moreover, the PL wavelengths of the CH 3 NH 3 PbBr 3- x Cl x NCs films were precisely tuned with steps as fine as 2 nm. Experimental results showed that NaCl dissolved in methanol solution can form Cl - (CH 3 OH) n , which brings ionized Cl into the polymer-encapsulated CH 3 NH 3 PbBr 3 NCs film for CH 3 NH 3 PbBr 3- x Cl x NCs film growth. Based on the swelling and anion exchange dynamics, a modified NaCl-CH 3 OH-MABr solution system was developed to trigger CH 3 NH 3 PbBr 3- x Cl x NCs film PL emission tuning from 528 to 463 nm with several-fold intensity enhancement. The realization of precisely controlled photoluminescence from the perovskite nanocrystal film would have wide applications in the optical and imaging fields.