(color online) (a) Left panel: normalized TRPL traces measured on the monolayer part of the MoS₂ flake at different temperatures from 4.5 K to 295 K. Right panel: plots of slow decay time constant (upper panel) of photo carrier recombination (τ_r) and amplitude of the TRPL traces (lower panel) as a function of temperature. (b) Normalized time-resolved PL dynamics at 4 K in log scale. The lines are all fitted by bi-exponential function, however, the initial time is too short to be fitted for X⁰, L1 and L2. The decay times are 33±5 ps for the second decay time of X, 32±2 ps for L1, 80±6 ps for L2. For trion, the short time constant is 18±2 ps and the long decay time constant is 30±3 ps. The small peaks marked by arrows superimposed on the X and trion come from laser reflections. (c) and (d) TRPL at 4 K with σ⁺ laser polarization excitation Left axis is X (c) and trion (d) PL emission (in log scale) with co-polarized (black lines) and cross-polarized (red lines) detection geometry with respect to the excitation laser as a function of time, and right axis is circular polarization degree of the PL emission. (c) Arrows show the periodic signal of laser reflections as the PL intensity decays. (d) Solid green line shows the polarization reproduced by a bi-exponential decay, using a fast decay time of and a long decay time . Dotted orange line shows lower bounds for and dotted purple line shows upper bounds for . Panel (a) is reproduced from Ref. [18]; panels (b)–(d) are reproduced from Ref. [23].