Large red shift from blue to green in the photoluminescence of pure CsPbBr3 nanoplatelets triggered by the cooperative effect of ligands combination

Abstract

With unique electronic and optical properties, the size and luminescence color of metal halide perovskite nanocrystals CsPbBr3 (CPB) are crucial for the potential applications including solid-state lighting, photovoltaics, and thermoelectrics. In this work, we have developed a viable design strategy toward cubic CPB nanoplatelet (NPs) with blue emission at 450–467 nm and a large red shift to the green region at 500–512 nm occurs through a cooperative effect of the ligands 4-bromo-butyric acid (BBA) and oleylamine (OLA). The influence of the molecular ratio of BBA/OLA, reaction time and temperature on the transformation from blue to green has been investigated systematically. The red shift in the PL of CPB NPs is ascribed to the growth of the crystals with decreased quantum confinement. The photoluminescence quantum yields (PLQYs) of the blue and green luminescence of the obtained CPB NPs reach 94.4 % and 84.4 %, respectively. This proposed strategy not only experimentally fabricates size-adjustable CPB NPs but also helps to reveal in depth the mechanisms of the large variation of quantum confinement in pure cubic CPB NPs.