Fig. 4

Pressure-induced emission mechanism associated exciton self-trapping in NCs. Configuration coordinate model of emission for the Cs₄PbBr₆ NCs at 1 atm (a) and 4 GPa (b). Herein, the absorption transition upon excitation from A to B is described. The STE recombination emission is depicted from C to D. The path between B and C refers to exciton self-trapping (red) and detrapping (green). (E_detrap): activation energy for detrapping, (E_ex1 and E_ex2): splitting of the bound exciton state, (ST): self-trapped state, (G): ground state, S^1/2: Huang-Rhys parameter