Low temperature synthesis of high-quality all-inorganic cesium lead halide perovskite nanocrystals in open air and their upconversion luminescence.

In this work, a single-step and low-cost synthesis of all-inorganic cesium lead halide perovskite nanocrystals was developed. PbX 2 and Cs 2 CO 3 were added to a mixture containing 1-octadecene (ODE), oleic acid (OA) and oleylamine (OLA), and heated at 80–100 °C for 15–30 min in air. The resultant high-quality cube-like CsPbX 3 nanocrystals are monodisperse with dimensions of 7–15 nm, and display strong photoluminescence (PL) with a narrow, tuneable emission band of 14–43 nm and a high quantum yield (∼90%). The mechanisms of nucleation and growth were investigated by testing the effects of temperature and surface ligands (OA/OLA) on the crystal morphology and PL intensity. The high quality of the CsPbX 3 nanocrystals was further confirmed by efficient upconversion PL with high energy gain, observed here for the first time for colloidal CsPb(Br/I) 3 nanocrystals, with an energy gain higher than 430 meV that was mainly attributed to anti-stokes generation rather than the multiphoton effect. [ABSTRACT FROM AUTHOR]