(a) Transport spectral functions α tr of the monolayer, bilayer, and T-bilayer. The main peak appears at ∼380 cm⁻¹ in the high-frequency region, which is consistent with the results of phonon linewidths. The peak value of the bilayer is much lower than those of the other two cases. (b) The electronic relaxation time τ of the monolayer, bilayer, and T-bilayer as a function of temperature T.