Fig. 5. Modeling of the ASE threshold using the kinetic equations and experimental parameter inputs.

(A) Schematics of the ASE process in neutral and charged CQDs. Blue hollow circles represent holes in the valence band. Black solid circles represent photogenerated electrons, while red solid circles denote excess electrons induced by the electric field. XX, X¹⁻, and X²⁻ are the same denotations as previously described in Fig. 4. (B and C) Emission intensity decay map normalized by the peak value of the photon density under each electric field at the pump fluence of 800 and 1000 μJ/cm², respectively. At 800 μJ/cm², the abrupt acceleration of emission (ASE) only occurs under the E-field threshold (20.13 kV/cm). The white dash line locates at the E-field threshold. At 1000 μJ/cm², the ASE can be observed under the electric field smaller than 149.2 kV/cm (white dash line). (D) Integrated photon density (log scale) map as a function of both the applied electric field (linear scale) and the pump fluence (log scale). The white dash line indicates the E-field threshold, and the blue dash line indicates the threshold behavior under different electric fields. (E) Simulated and experimental ASE threshold behavior as a function of the applied electric field.