Despite many successful realizations of laser operations in various micro/nanostructured lead halide perovskites (LHPs), the electron–hole plasma (EHP) lasing dynamics has only rarely been reported, especially for wide-gap Cl-rich perovskites. In this work, the temporal lasing dynamics of whispering gallery mode (WGM) CsPbCl m Br3–m microplate lasers are systematically investigated, for the first time, with a streak camera system. As the pump fluence increases, the gain profile exhibits a monotonous redshift, indicating the EHP lasing in the microplate cavity, while an opposite shift of the gain region is observed with time decay due to the gradual depletion of carriers. This directly reflects the change of the bandgap renormalization effect at varying pump fluences. Additionally, the individual lasing modes present identifiable blueshifts with elevated pump levels and redshifts with time delay, which can be unraveled by the carrier-induced refractive index change in the LHP cavity. Moreover, the wavelength-dependent lasing duration demonstrates that lasing in the EHP regime depends not only on the carrier density, but also on the bandgap variation with carrier density. By directly modulating the pump fluence, the onset delay of the microlaser can be efficiently tuned. Our results provide a comprehensive understanding of the EHP lasing mechanism and carrier dynamics in the WGM LHP micro/nanolasers and will push their technological relevance in integrated photonics.

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A comparative study with focusing on carrier recombination properties in Cu2ZnSn(S,Se)4 (CZTSSe) and the CuInGaSe2 (CIGS) solar cells has been carried out. For this purpose, electroluminescence (EL) and also bias-dependent time resolved photoluminescence (TRPL) using femtosecond (fs) laser source were performed. For the similar forward current density, the EL-intensity of the CZTSSe sample was obtained significantly lower than that of the CIGS sample. Primarily, it can be attributed to the existence of excess amount of non-radiative recombination center in the CZTSSe, and/or CZTSSe/CdS interface comparing to that of CIGS sample. In case of CIGS sample, TRPL decay time was found to increase with the application of forward-bias. This can be attributed to the reduced charge separation rate resulting from the reduced electric-field at the junction. However, in CZTSSe sample, TRPL decay time has been found almost independent under the forward and reverse-bias conditions. This phenomenon indicates that the charge recombination rate strongly dominates over the charge separation rate across the junction of the CZTSSe sample. Finally, temperature dependent VOC suggests that interface related recombination in the CZTSSe solar cell structure might be one of the major factors that affect EL-intensity and also, TRPL decay curves.