Synthesis of CsPbBr3 perovskite nanocrystals
Cesium oleate is prepared by loading 203.6 mg Cesium carbonate , 10 mL octadecene (ODE) and 0.63 mL of Oleic acid were loaded into a 100 mL three-neck flask. The solution is stirred at 600 rpm and degassed at 120 0 C for 1 hour after which it is heated to 150 0 C under N2 atmosphere.
The lead precursor is prepared by mixing 398mg of PbBr2 , 25 mL of ODE, 2.5 mL of OA and 2.5 mL of Oleylamine in a 100mL three-neck flask and degassed at 120 0 C for 1 hour, and heated to 150 0C under N2.
The precursor is then heated to 180 for injection. Cesium oleate solution 2 mL is quickly injected with a glass syringe.
After 10 s, the flask is cooled down in an ice water bath. 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.
Figure. 1 (a) The synthesis process of CsPbBr3 perovskite nanocrystals using hot injection method. (b) XRD of various of CsPbBr3 samples. (c) TEM image of CsPbBr3 nanocrystals. (d) Different emitting colloidal solutions of perovskite nanocrystals under 365 nm excitation . (e ) Absorbance and PL intensity of synthesized nanocrystals. (f) XPS of the halide element of the nanocrystals for varying CsPbBr3 samples.
Characterization
The UV-vis absorption spectra were recorded by Varian 5E UV/VIS/NIR spectrophotometer. X-ray diffraction (XRD) was conducted using an X’Pert-MPD diffractometer (Philips, Netherlands). Photoluminescence (PL) spectra were measure using Photon Technology International Flourometer (PTI, USA). Fourier Transform Infra-Red Spectroscopy (FTIR) was measured using JASCO(FT-4100). Transmission electron microscopy (TEM) were performed using a Hitachi H-7500. 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 .
The XPS analysis was performed using KRATOS Analytical system. For measuring XPS, the nanocrystals were spin-coated on glass substrates.