Application of the Quantum Confinement Effect in the Determination of Activation Energy: Growth of CsPbBr₃ Nanocrystals Under Stirring Conditions

Determining the activation energy is of great importance in understanding the growth kinetics of crystalline materials. In this work, we investigate the feasibility of using the temperature dependence of the Stokes shift and bandgap from the Tauc plot of the absorbance spectrum to determine the activation energy for the growth of cesium lead bromide (CsPbBr3) nanocrystals (NCs) under stirring conditions. The principle is based on the quantum confinement effect, i.e., the size dependence of the bandgap of semiconductor NCs. The nominal activation energies determined by using the temperature dependences of the bandgap from the Tauc plot and the Stokes shift exhibit the same increasing trend with the increase of stirring speed as the corresponding ones determined by the temperature dependences of the crystal size of CsPbBr3 NCs and the photoluminescence (PL) peak wavelength. The nominal activation energies determined by using the temperature dependences of the PL peak wavelength, the crystal size, and the bandgap from the Tauc plot are in good accordance with each other. However, the nominal activation energies determined by using the Stokes shift are slightly larger than the corresponding energies determined by the other approaches. There might exist other factors contributing to the Stokes shift in addition to the size effect. These results highlight that the Stokes shift and absorbance analyses have the potential for analyzing the growth behavior of semiconductor NCs under dynamic synthesis conditions.