Heat-up synthesis of CsPbBr3 perovskite nanocrystals
Cs(oleate) solution is prepared by dissolving 3.2 g of Cs2CO3 in 28 mL of mixed solution of oleic acid (OA) and octadecene at 110 ℃ under vacuum. Pb(oleate)2 solution is prepared by dissolving 2.2 g of PbO in 10 mL of mixed solution of OA and octadecene at 110 ℃ under vacuum.
17 mL of bromododecane, 1 mL of OA, 0.3 mL of Cs(oleate) solution, 2 mL of Pb(oleate)2 solution, and 10 mL of mixed solution of oleylamine and octadecene were mixed in a single reactor. The precursor solutions were heated up to 110 ℃ and cooled to room temperature.
The crude solution is purified in MeOAc anti-solvent with a ratio of 1:3 and centrifuged at 8,000 rpm for 3 minutes.
Finally the precipitant is then dispersed in hexane and stored in N2 environment.
For scale-up, the molar amount of each precursor was proportionally increased up to the desired scale.
Figure 1. (a) Schematic illustration of heat-up process for the synthesis of green-emitting CsPbBr3 nanocrystals. (b) UV–Vis absorption and PL spectra of green-emitting CsPbBr3 nanocrystals synthesized using heat-up method. (c) TEM images and (d) DLS plots of CsPbBr3 nanocrystals synthesized using heat-up method and hot-injection method, respectively. (e) UV–Vis absorption and PL spectra and TEM images of blue-emitting CsPbBr3 nanoplatelets synthesized using heat-up method.
Characterization
UV–Vis absorption spectroscopy was carried out using a V-770 UV–Vis spectrophotometer (Jasco). PL spectra and PLQYs were measured using a FluoroMax Plus spectrophotometer (Horiba). HR-TEM images were obtained using a JEM 2100F transmission electron microscope (JEOL). The films for TEM measurement was prepared by diluting colloidal solutions in hexane solution and dropped mesh grid with a pipette and dried in vacuum . DLS plots and PDI values were gained using a ELSZ-1000 zetapotential and particle size analyzer (Otsuka Electronics).