Manipulating hot carrier behavior of MAPbBr3 nanocrystal by photon flux and temperature

The temperature-dependent time-resolved spectroscopies are employed to investigate the hot carrier characteristics in MAPbBr3 nanocrystals (NCs). Simultaneously, the absorption and photoluminescence data exhibits that MAPbBr3 NCs pass through cubic phase and tetragonal phase in turn as the temperature drops. As the phase transition from the cubic phase to the tetragonal phase, the band gap narrows, the shallow defects population that participates in the carrier dynamics and the Longitudinal-optical phonon energy (ELO) decreases. We uncovered that the hot carrier can be induced in the MAPbBr3 NCs through changing the photon flux and the temperature. Moreover, the hot carrier cooling time and the carrier heating effect in tetragonal phase improved in comparison with those in cubic phase, owing to the influence of bandgap, shallow defect and ELO as mentioned above. These results can help us to further understand the hot carrier characteristics in the perovskite MAPbBr3 NCs for designing and optimizing the perovskite-based optoelectronic devices of high performance.