Probing molecule-like isolated octahedra via-phase stabilization of zero-dimensional cesium lead halide nanocrystals.

Arunkumar, Paulraj; Cho, Han Bin; Gil, Kyeong Hun; Unithrattil, Sanjith; Kim, Yoon Hwa; Bin Im, Won · Nat Commun · 2018

basic_science · Level V

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Abstract

Zero-dimensional (0D) inorganic perovskites have recently emerged as an interesting class of material owing to their intrinsic Pb<sup>2+</sup> emission, polaron formation, and large exciton binding energy. They have a unique quantum-confined structure, originating from the complete isolation of octahedra exhibiting single-molecule behavior. Herein, we probe the optical behavior of single-molecule-like isolated octahedra in 0D Cesium lead halide (Cs<sub>4</sub>PbX<sub>6</sub>, X = Cl, Br/Cl, Br) nanocrystals through isovalent manganese doping at lead sites. The incorporation of manganese induced phase stabilization of 0D Cs<sub>4</sub>PbX<sub>6</sub> over CsPbX<sub>3</sub> by lowering the symmetry of PbX<sub>6</sub> via enhanced octahedral distortion. This approach enables the synthesis of CsPbX<sub>3</sub> free Cs<sub>4</sub>PbX<sub>6</sub> nanocrystals. A high photoluminescence quantum yield for manganese emission was obtained in colloidal (29%) and solid (21%, powder) forms. These performances can be attributed to structure-induced confinement effects, which enhance the energy transfer from localized host exciton states to Mn<sup>2+</sup> dopant within the isolated octahedra.